[PATCH 0/2 v7]: printk, Add monotonic and real printk timestamps

[PATCH 0/2 v7]: printk, Add monotonic and real printk timestamps

[Prarit Bhargava]

This patchset adds monotonic and real printk timestamps.  The first patch
changes CONFIG_PRINT_TIME from a bool to an int to allow for the additional
timestamps that are added in patch 2.

Changes from v6: Petr Mladek pointed out that the current patch causes problems
for dmesg (and potentially other utilities).  I will post the patch here

http://marc.info/?l=linux-kernel&m=146124485215811&w=2

to fix dmesg once this feature is positively reviewed.

Prarit Bhargava (2):
  lib, switch CONFIG_PRINTK_TIME to int
  printk, allow different timestamps for printk.time

 Documentation/kernel-parameters.txt                |    6 +-
 arch/arm/configs/axm55xx_defconfig                 |    2 +-
 arch/arm/configs/bcm2835_defconfig                 |    2 +-
 arch/arm/configs/bcm_defconfig                     |    2 +-
 arch/arm/configs/colibri_pxa270_defconfig          |    2 +-
 arch/arm/configs/colibri_pxa300_defconfig          |    2 +-
 arch/arm/configs/dove_defconfig                    |    2 +-
 arch/arm/configs/efm32_defconfig                   |    2 +-
 arch/arm/configs/exynos_defconfig                  |    2 +-
 arch/arm/configs/ezx_defconfig                     |    2 +-
 arch/arm/configs/h5000_defconfig                   |    2 +-
 arch/arm/configs/hisi_defconfig                    |    2 +-
 arch/arm/configs/imote2_defconfig                  |    2 +-
 arch/arm/configs/imx_v6_v7_defconfig               |    2 +-
 arch/arm/configs/keystone_defconfig                |    2 +-
 arch/arm/configs/lpc18xx_defconfig                 |    2 +-
 arch/arm/configs/magician_defconfig                |    2 +-
 arch/arm/configs/mmp2_defconfig                    |    2 +-
 arch/arm/configs/moxart_defconfig                  |    2 +-
 arch/arm/configs/multi_v7_defconfig                |    2 +-
 arch/arm/configs/mvebu_v7_defconfig                |    2 +-
 arch/arm/configs/mxs_defconfig                     |    2 +-
 arch/arm/configs/omap2plus_defconfig               |    2 +-
 arch/arm/configs/pxa168_defconfig                  |    2 +-
 arch/arm/configs/pxa3xx_defconfig                  |    2 +-
 arch/arm/configs/pxa910_defconfig                  |    2 +-
 arch/arm/configs/pxa_defconfig                     |    2 +-
 arch/arm/configs/qcom_defconfig                    |    2 +-
 arch/arm/configs/raumfeld_defconfig                |    2 +-
 arch/arm/configs/shmobile_defconfig                |    2 +-
 arch/arm/configs/socfpga_defconfig                 |    2 +-
 arch/arm/configs/stm32_defconfig                   |    2 +-
 arch/arm/configs/sunxi_defconfig                   |    2 +-
 arch/arm/configs/tegra_defconfig                   |    2 +-
 arch/arm/configs/u300_defconfig                    |    2 +-
 arch/arm/configs/u8500_defconfig                   |    2 +-
 arch/arm/configs/vt8500_v6_v7_defconfig            |    2 +-
 arch/arm/configs/xcep_defconfig                    |    2 +-
 arch/arm/configs/zx_defconfig                      |    2 +-
 arch/arm64/configs/defconfig                       |    2 +-
 arch/mips/configs/bcm47xx_defconfig                |    2 +-
 arch/mips/configs/bmips_be_defconfig               |    2 +-
 arch/mips/configs/bmips_stb_defconfig              |    2 +-
 arch/mips/configs/ci20_defconfig                   |    2 +-
 arch/mips/configs/lemote2f_defconfig               |    2 +-
 arch/mips/configs/loongson3_defconfig              |    2 +-
 arch/mips/configs/nlm_xlp_defconfig                |    2 +-
 arch/mips/configs/nlm_xlr_defconfig                |    2 +-
 arch/mips/configs/pistachio_defconfig              |    2 +-
 arch/mips/configs/qi_lb60_defconfig                |    2 +-
 arch/mips/configs/rt305x_defconfig                 |    2 +-
 arch/mips/configs/xway_defconfig                   |    2 +-
 arch/parisc/configs/generic-64bit_defconfig        |    2 +-
 arch/powerpc/configs/40x/virtex_defconfig          |    2 +-
 arch/powerpc/configs/44x/virtex5_defconfig         |    2 +-
 arch/powerpc/configs/44x/warp_defconfig            |    2 +-
 arch/powerpc/configs/52xx/cm5200_defconfig         |    2 +-
 arch/powerpc/configs/52xx/lite5200b_defconfig      |    2 +-
 arch/powerpc/configs/52xx/motionpro_defconfig      |    2 +-
 arch/powerpc/configs/52xx/tqm5200_defconfig        |    2 +-
 arch/powerpc/configs/gamecube_defconfig            |    2 +-
 arch/powerpc/configs/mpc5200_defconfig             |    2 +-
 arch/powerpc/configs/pasemi_defconfig              |    2 +-
 arch/powerpc/configs/wii_defconfig                 |    2 +-
 arch/s390/configs/default_defconfig                |    2 +-
 arch/s390/configs/gcov_defconfig                   |    2 +-
 arch/s390/configs/performance_defconfig            |    2 +-
 arch/s390/configs/zfcpdump_defconfig               |    2 +-
 arch/sh/configs/edosk7760_defconfig                |    2 +-
 arch/sh/configs/sdk7786_defconfig                  |    2 +-
 arch/sh/configs/se7722_defconfig                   |    2 +-
 arch/sh/configs/sh7785lcr_32bit_defconfig          |    2 +-
 arch/sh/configs/urquell_defconfig                  |    2 +-
 arch/sparc/configs/sparc64_defconfig               |    2 +-
 arch/x86/configs/i386_defconfig                    |    2 +-
 arch/x86/configs/x86_64_defconfig                  |    2 +-
 arch/xtensa/configs/audio_kc705_defconfig          |    2 +-
 arch/xtensa/configs/generic_kc705_defconfig        |    2 +-
 arch/xtensa/configs/nommu_kc705_defconfig          |    2 +-
 arch/xtensa/configs/smp_lx200_defconfig            |    2 +-
 include/linux/timekeeping.h                        |    1 +
 kernel/printk/printk.c                             |   76 ++++++++++++++++++--
 kernel/time/timekeeping.c                          |   13 ++++
 lib/Kconfig.debug                                  |    8 ++-
 .../selftests/rcutorture/configs/lock/CFcommon     |    2 +-
 .../selftests/rcutorture/configs/rcu/CFcommon      |    2 +-
 86 files changed, 177 insertions(+), 89 deletions(-)

-- 
1.7.9.3

[PATCH 1/2] lib, switch CONFIG_PRINTK_TIME to int

[Prarit Bhargava]

CONFIG_PRINTK_TIME is a bool and in order to add timestamp options for
the monotonic and real time clock it must be expanded to an int.

Cc: Petr Mladek <pmladek@suse.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Xunlei Pang <pang.xunlei@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Baolin Wang <baolin.wang@linaro.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Petr Mladek <pmladek@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Vasily Averin <vvs@virtuozzo.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
---
 Documentation/kernel-parameters.txt                |    2 +-
 arch/arm/configs/axm55xx_defconfig                 |    2 +-
 arch/arm/configs/bcm2835_defconfig                 |    2 +-
 arch/arm/configs/bcm_defconfig                     |    2 +-
 arch/arm/configs/colibri_pxa270_defconfig          |    2 +-
 arch/arm/configs/colibri_pxa300_defconfig          |    2 +-
 arch/arm/configs/dove_defconfig                    |    2 +-
 arch/arm/configs/efm32_defconfig                   |    2 +-
 arch/arm/configs/exynos_defconfig                  |    2 +-
 arch/arm/configs/ezx_defconfig                     |    2 +-
 arch/arm/configs/h5000_defconfig                   |    2 +-
 arch/arm/configs/hisi_defconfig                    |    2 +-
 arch/arm/configs/imote2_defconfig                  |    2 +-
 arch/arm/configs/imx_v6_v7_defconfig               |    2 +-
 arch/arm/configs/keystone_defconfig                |    2 +-
 arch/arm/configs/lpc18xx_defconfig                 |    2 +-
 arch/arm/configs/magician_defconfig                |    2 +-
 arch/arm/configs/mmp2_defconfig                    |    2 +-
 arch/arm/configs/moxart_defconfig                  |    2 +-
 arch/arm/configs/multi_v7_defconfig                |    2 +-
 arch/arm/configs/mvebu_v7_defconfig                |    2 +-
 arch/arm/configs/mxs_defconfig                     |    2 +-
 arch/arm/configs/omap2plus_defconfig               |    2 +-
 arch/arm/configs/pxa168_defconfig                  |    2 +-
 arch/arm/configs/pxa3xx_defconfig                  |    2 +-
 arch/arm/configs/pxa910_defconfig                  |    2 +-
 arch/arm/configs/pxa_defconfig                     |    2 +-
 arch/arm/configs/qcom_defconfig                    |    2 +-
 arch/arm/configs/raumfeld_defconfig                |    2 +-
 arch/arm/configs/shmobile_defconfig                |    2 +-
 arch/arm/configs/socfpga_defconfig                 |    2 +-
 arch/arm/configs/stm32_defconfig                   |    2 +-
 arch/arm/configs/sunxi_defconfig                   |    2 +-
 arch/arm/configs/tegra_defconfig                   |    2 +-
 arch/arm/configs/u300_defconfig                    |    2 +-
 arch/arm/configs/u8500_defconfig                   |    2 +-
 arch/arm/configs/vt8500_v6_v7_defconfig            |    2 +-
 arch/arm/configs/xcep_defconfig                    |    2 +-
 arch/arm/configs/zx_defconfig                      |    2 +-
 arch/arm64/configs/defconfig                       |    2 +-
 arch/mips/configs/bcm47xx_defconfig                |    2 +-
 arch/mips/configs/bmips_be_defconfig               |    2 +-
 arch/mips/configs/bmips_stb_defconfig              |    2 +-
 arch/mips/configs/ci20_defconfig                   |    2 +-
 arch/mips/configs/lemote2f_defconfig               |    2 +-
 arch/mips/configs/loongson3_defconfig              |    2 +-
 arch/mips/configs/nlm_xlp_defconfig                |    2 +-
 arch/mips/configs/nlm_xlr_defconfig                |    2 +-
 arch/mips/configs/pistachio_defconfig              |    2 +-
 arch/mips/configs/qi_lb60_defconfig                |    2 +-
 arch/mips/configs/rt305x_defconfig                 |    2 +-
 arch/mips/configs/xway_defconfig                   |    2 +-
 arch/parisc/configs/generic-64bit_defconfig        |    2 +-
 arch/powerpc/configs/40x/virtex_defconfig          |    2 +-
 arch/powerpc/configs/44x/virtex5_defconfig         |    2 +-
 arch/powerpc/configs/44x/warp_defconfig            |    2 +-
 arch/powerpc/configs/52xx/cm5200_defconfig         |    2 +-
 arch/powerpc/configs/52xx/lite5200b_defconfig      |    2 +-
 arch/powerpc/configs/52xx/motionpro_defconfig      |    2 +-
 arch/powerpc/configs/52xx/tqm5200_defconfig        |    2 +-
 arch/powerpc/configs/gamecube_defconfig            |    2 +-
 arch/powerpc/configs/mpc5200_defconfig             |    2 +-
 arch/powerpc/configs/pasemi_defconfig              |    2 +-
 arch/powerpc/configs/wii_defconfig                 |    2 +-
 arch/s390/configs/default_defconfig                |    2 +-
 arch/s390/configs/gcov_defconfig                   |    2 +-
 arch/s390/configs/performance_defconfig            |    2 +-
 arch/s390/configs/zfcpdump_defconfig               |    2 +-
 arch/sh/configs/edosk7760_defconfig                |    2 +-
 arch/sh/configs/sdk7786_defconfig                  |    2 +-
 arch/sh/configs/se7722_defconfig                   |    2 +-
 arch/sh/configs/sh7785lcr_32bit_defconfig          |    2 +-
 arch/sh/configs/urquell_defconfig                  |    2 +-
 arch/sparc/configs/sparc64_defconfig               |    2 +-
 arch/x86/configs/i386_defconfig                    |    2 +-
 arch/x86/configs/x86_64_defconfig                  |    2 +-
 arch/xtensa/configs/audio_kc705_defconfig          |    2 +-
 arch/xtensa/configs/generic_kc705_defconfig        |    2 +-
 arch/xtensa/configs/nommu_kc705_defconfig          |    2 +-
 arch/xtensa/configs/smp_lx200_defconfig            |    2 +-
 kernel/printk/printk.c                             |   41 +++++++++++++++++++-
 lib/Kconfig.debug                                  |    7 +++-
 .../selftests/rcutorture/configs/lock/CFcommon     |    2 +-
 .../selftests/rcutorture/configs/rcu/CFcommon      |    2 +-
 84 files changed, 126 insertions(+), 86 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 0b3de80..79c3e28 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -3112,7 +3112,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			default: disabled
 
 	printk.time=	Show timing data prefixed to each printk message line
-			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
+			Format: <string>  (1/Y/y=enable, 0/N/n=disable)
 
 	processor.max_cstate=	[HW,ACPI]
 			Limit processor to maximum C-state
diff --git a/arch/arm/configs/axm55xx_defconfig b/arch/arm/configs/axm55xx_defconfig
index d3260d7..55eba35 100644
--- a/arch/arm/configs/axm55xx_defconfig
+++ b/arch/arm/configs/axm55xx_defconfig
@@ -232,7 +232,7 @@ CONFIG_NFS_FSCACHE=y
 CONFIG_SUNRPC_DEBUG=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_FS=y
 CONFIG_MAGIC_SYSRQ=y
diff --git a/arch/arm/configs/bcm2835_defconfig b/arch/arm/configs/bcm2835_defconfig
index 1ef69fc..b96aeb5 100644
--- a/arch/arm/configs/bcm2835_defconfig
+++ b/arch/arm/configs/bcm2835_defconfig
@@ -127,7 +127,7 @@ CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ASCII=y
 CONFIG_NLS_ISO8859_1=y
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_BOOT_PRINTK_DELAY=y
 CONFIG_DYNAMIC_DEBUG=y
 CONFIG_DEBUG_INFO=y
diff --git a/arch/arm/configs/bcm_defconfig b/arch/arm/configs/bcm_defconfig
index 7117662..19710f4 100644
--- a/arch/arm/configs/bcm_defconfig
+++ b/arch/arm/configs/bcm_defconfig
@@ -121,7 +121,7 @@ CONFIG_CONFIGFS_FS=y
 # CONFIG_MISC_FILESYSTEMS is not set
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_FS=y
 CONFIG_MAGIC_SYSRQ=y
diff --git a/arch/arm/configs/colibri_pxa270_defconfig b/arch/arm/configs/colibri_pxa270_defconfig
index 0b9211b..99b7062 100644
--- a/arch/arm/configs/colibri_pxa270_defconfig
+++ b/arch/arm/configs/colibri_pxa270_defconfig
@@ -156,7 +156,7 @@ CONFIG_NLS_ASCII=y
 CONFIG_NLS_ISO8859_1=m
 CONFIG_NLS_ISO8859_15=m
 CONFIG_NLS_UTF8=m
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_FS=y
 CONFIG_DEBUG_KERNEL=y
diff --git a/arch/arm/configs/colibri_pxa300_defconfig b/arch/arm/configs/colibri_pxa300_defconfig
index be02fe2..3a0b92b 100644
--- a/arch/arm/configs/colibri_pxa300_defconfig
+++ b/arch/arm/configs/colibri_pxa300_defconfig
@@ -58,7 +58,7 @@ CONFIG_INOTIFY=y
 CONFIG_NFS_FS=y
 CONFIG_NFS_V3=y
 CONFIG_ROOT_NFS=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_KERNEL=y
 CONFIG_DEBUG_INFO=y
 # CONFIG_RCU_CPU_STALL_DETECTOR is not set
diff --git a/arch/arm/configs/dove_defconfig b/arch/arm/configs/dove_defconfig
index 701677f..d952d3d 100644
--- a/arch/arm/configs/dove_defconfig
+++ b/arch/arm/configs/dove_defconfig
@@ -119,7 +119,7 @@ CONFIG_NLS_CODEPAGE_850=y
 CONFIG_NLS_ISO8859_1=y
 CONFIG_NLS_ISO8859_2=y
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_FS=y
 # CONFIG_SCHED_DEBUG is not set
diff --git a/arch/arm/configs/efm32_defconfig b/arch/arm/configs/efm32_defconfig
index c0dac0f0f..306d156 100644
--- a/arch/arm/configs/efm32_defconfig
+++ b/arch/arm/configs/efm32_defconfig
@@ -93,7 +93,7 @@ CONFIG_EXT2_FS=y
 CONFIG_ROMFS_FS=y
 CONFIG_ROMFS_BACKED_BY_MTD=y
 # CONFIG_NETWORK_FILESYSTEMS is not set
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 # CONFIG_ENABLE_WARN_DEPRECATED is not set
 # CONFIG_ENABLE_MUST_CHECK is not set
diff --git a/arch/arm/configs/exynos_defconfig b/arch/arm/configs/exynos_defconfig
index 6ffd7e7..be9345d 100644
--- a/arch/arm/configs/exynos_defconfig
+++ b/arch/arm/configs/exynos_defconfig
@@ -229,7 +229,7 @@ CONFIG_ROOT_NFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ASCII=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_FS=y
 CONFIG_MAGIC_SYSRQ=y
diff --git a/arch/arm/configs/ezx_defconfig b/arch/arm/configs/ezx_defconfig
index ea316c4..c4bdecd 100644
--- a/arch/arm/configs/ezx_defconfig
+++ b/arch/arm/configs/ezx_defconfig
@@ -379,7 +379,7 @@ CONFIG_NLS_ISO8859_15=m
 CONFIG_NLS_KOI8_R=m
 CONFIG_NLS_KOI8_U=m
 CONFIG_NLS_UTF8=m
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_FS=y
 CONFIG_DEBUG_KERNEL=y
 # CONFIG_SCHED_DEBUG is not set
diff --git a/arch/arm/configs/h5000_defconfig b/arch/arm/configs/h5000_defconfig
index 37903e3..e3507cb 100644
--- a/arch/arm/configs/h5000_defconfig
+++ b/arch/arm/configs/h5000_defconfig
@@ -66,7 +66,7 @@ CONFIG_TMPFS=y
 CONFIG_JFFS2_FS=y
 CONFIG_JFFS2_COMPRESSION_OPTIONS=y
 # CONFIG_NETWORK_FILESYSTEMS is not set
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_KERNEL=y
 # CONFIG_SCHED_DEBUG is not set
 # CONFIG_DEBUG_BUGVERBOSE is not set
diff --git a/arch/arm/configs/hisi_defconfig b/arch/arm/configs/hisi_defconfig
index b2e340b..4dc0a4a 100644
--- a/arch/arm/configs/hisi_defconfig
+++ b/arch/arm/configs/hisi_defconfig
@@ -82,7 +82,7 @@ CONFIG_NFS_FS=y
 CONFIG_NFS_V3_ACL=y
 CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_FS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
diff --git a/arch/arm/configs/imote2_defconfig b/arch/arm/configs/imote2_defconfig
index 18e59fe..672010d 100644
--- a/arch/arm/configs/imote2_defconfig
+++ b/arch/arm/configs/imote2_defconfig
@@ -350,7 +350,7 @@ CONFIG_NLS_ISO8859_15=m
 CONFIG_NLS_KOI8_R=m
 CONFIG_NLS_KOI8_U=m
 CONFIG_NLS_UTF8=m
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_FS=y
 CONFIG_DEBUG_KERNEL=y
 # CONFIG_SCHED_DEBUG is not set
diff --git a/arch/arm/configs/imx_v6_v7_defconfig b/arch/arm/configs/imx_v6_v7_defconfig
index 978c5de..80ec5f4 100644
--- a/arch/arm/configs/imx_v6_v7_defconfig
+++ b/arch/arm/configs/imx_v6_v7_defconfig
@@ -360,7 +360,7 @@ CONFIG_NLS_ASCII=y
 CONFIG_NLS_ISO8859_1=y
 CONFIG_NLS_ISO8859_15=m
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_FS=y
 CONFIG_MAGIC_SYSRQ=y
 # CONFIG_SCHED_DEBUG is not set
diff --git a/arch/arm/configs/keystone_defconfig b/arch/arm/configs/keystone_defconfig
index 5bcc9cf..d402c59 100644
--- a/arch/arm/configs/keystone_defconfig
+++ b/arch/arm/configs/keystone_defconfig
@@ -195,7 +195,7 @@ CONFIG_NFSD_V3=y
 CONFIG_NFSD_V3_ACL=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_SHIRQ=y
 CONFIG_DEBUG_USER=y
diff --git a/arch/arm/configs/lpc18xx_defconfig b/arch/arm/configs/lpc18xx_defconfig
index 2ae00b0..c25ff23 100644
--- a/arch/arm/configs/lpc18xx_defconfig
+++ b/arch/arm/configs/lpc18xx_defconfig
@@ -159,7 +159,7 @@ CONFIG_EXT2_FS=y
 # CONFIG_INOTIFY_USER is not set
 CONFIG_JFFS2_FS=y
 # CONFIG_NETWORK_FILESYSTEMS is not set
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 # CONFIG_ENABLE_WARN_DEPRECATED is not set
 # CONFIG_ENABLE_MUST_CHECK is not set
diff --git a/arch/arm/configs/magician_defconfig b/arch/arm/configs/magician_defconfig
index a5b4920..accbf10 100644
--- a/arch/arm/configs/magician_defconfig
+++ b/arch/arm/configs/magician_defconfig
@@ -167,7 +167,7 @@ CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_CODEPAGE_1251=m
 CONFIG_NLS_ISO8859_1=y
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_KERNEL=y
 # CONFIG_SCHED_DEBUG is not set
 CONFIG_TIMER_STATS=y
diff --git a/arch/arm/configs/mmp2_defconfig b/arch/arm/configs/mmp2_defconfig
index f1cb95e..0385e4a 100644
--- a/arch/arm/configs/mmp2_defconfig
+++ b/arch/arm/configs/mmp2_defconfig
@@ -81,7 +81,7 @@ CONFIG_NFS_V3=y
 CONFIG_NFS_V3_ACL=y
 CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_FS=y
 CONFIG_DEBUG_KERNEL=y
diff --git a/arch/arm/configs/moxart_defconfig b/arch/arm/configs/moxart_defconfig
index a3cb76c..32fab5a 100644
--- a/arch/arm/configs/moxart_defconfig
+++ b/arch/arm/configs/moxart_defconfig
@@ -124,7 +124,7 @@ CONFIG_EXT3_FS=y
 CONFIG_TMPFS=y
 CONFIG_CONFIGFS_FS=y
 CONFIG_JFFS2_FS=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 # CONFIG_ENABLE_WARN_DEPRECATED is not set
 # CONFIG_ENABLE_MUST_CHECK is not set
diff --git a/arch/arm/configs/multi_v7_defconfig b/arch/arm/configs/multi_v7_defconfig
index 2823490..f9361a2 100644
--- a/arch/arm/configs/multi_v7_defconfig
+++ b/arch/arm/configs/multi_v7_defconfig
@@ -822,7 +822,7 @@ CONFIG_ROOT_NFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_FS=y
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_LOCKUP_DETECTOR=y
diff --git a/arch/arm/configs/mvebu_v7_defconfig b/arch/arm/configs/mvebu_v7_defconfig
index dc5797a..fdd7a29 100644
--- a/arch/arm/configs/mvebu_v7_defconfig
+++ b/arch/arm/configs/mvebu_v7_defconfig
@@ -147,7 +147,7 @@ CONFIG_NLS_CODEPAGE_850=y
 CONFIG_NLS_ISO8859_1=y
 CONFIG_NLS_ISO8859_2=y
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_FS=y
 CONFIG_MAGIC_SYSRQ=y
diff --git a/arch/arm/configs/mxs_defconfig b/arch/arm/configs/mxs_defconfig
index 6e0f751..8a3d2f2 100644
--- a/arch/arm/configs/mxs_defconfig
+++ b/arch/arm/configs/mxs_defconfig
@@ -166,7 +166,7 @@ CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_CODEPAGE_850=y
 CONFIG_NLS_ISO8859_1=y
 CONFIG_NLS_ISO8859_15=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_FRAME_WARN=2048
 CONFIG_UNUSED_SYMBOLS=y
diff --git a/arch/arm/configs/omap2plus_defconfig b/arch/arm/configs/omap2plus_defconfig
index 156bc88..112e5a9 100644
--- a/arch/arm/configs/omap2plus_defconfig
+++ b/arch/arm/configs/omap2plus_defconfig
@@ -465,7 +465,7 @@ CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_INFO_SPLIT=y
 CONFIG_DEBUG_INFO_DWARF4=y
diff --git a/arch/arm/configs/pxa168_defconfig b/arch/arm/configs/pxa168_defconfig
index 74d7e01..5824b89 100644
--- a/arch/arm/configs/pxa168_defconfig
+++ b/arch/arm/configs/pxa168_defconfig
@@ -57,7 +57,7 @@ CONFIG_NFS_V3=y
 CONFIG_NFS_V3_ACL=y
 CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_KERNEL=y
 # CONFIG_DEBUG_PREEMPT is not set
diff --git a/arch/arm/configs/pxa3xx_defconfig b/arch/arm/configs/pxa3xx_defconfig
index 5f337d7..e60d656 100644
--- a/arch/arm/configs/pxa3xx_defconfig
+++ b/arch/arm/configs/pxa3xx_defconfig
@@ -117,7 +117,7 @@ CONFIG_NFS_V3_ACL=y
 CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
 CONFIG_NLS=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_KERNEL=y
 CONFIG_DEBUG_SHIRQ=y
diff --git a/arch/arm/configs/pxa910_defconfig b/arch/arm/configs/pxa910_defconfig
index 3bb7771..a2f6f08 100644
--- a/arch/arm/configs/pxa910_defconfig
+++ b/arch/arm/configs/pxa910_defconfig
@@ -65,7 +65,7 @@ CONFIG_NFS_V3=y
 CONFIG_NFS_V3_ACL=y
 CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_KERNEL=y
 # CONFIG_DEBUG_PREEMPT is not set
diff --git a/arch/arm/configs/pxa_defconfig b/arch/arm/configs/pxa_defconfig
index dc5517e..621c4dc 100644
--- a/arch/arm/configs/pxa_defconfig
+++ b/arch/arm/configs/pxa_defconfig
@@ -734,7 +734,7 @@ CONFIG_NLS_ASCII=m
 CONFIG_NLS_ISO8859_1=m
 CONFIG_NLS_ISO8859_15=m
 CONFIG_NLS_UTF8=m
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DYNAMIC_DEBUG=y
 CONFIG_DEBUG_INFO=y
 CONFIG_FRAME_WARN=0
diff --git a/arch/arm/configs/qcom_defconfig b/arch/arm/configs/qcom_defconfig
index 7bff7bf..5dfac70 100644
--- a/arch/arm/configs/qcom_defconfig
+++ b/arch/arm/configs/qcom_defconfig
@@ -181,7 +181,7 @@ CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ASCII=y
 CONFIG_NLS_ISO8859_1=y
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DYNAMIC_DEBUG=y
 CONFIG_DEBUG_INFO=y
 CONFIG_MAGIC_SYSRQ=y
diff --git a/arch/arm/configs/raumfeld_defconfig b/arch/arm/configs/raumfeld_defconfig
index 3d833ae..b836f8f 100644
--- a/arch/arm/configs/raumfeld_defconfig
+++ b/arch/arm/configs/raumfeld_defconfig
@@ -196,7 +196,7 @@ CONFIG_NLS_ISO8859_15=y
 CONFIG_NLS_KOI8_R=y
 CONFIG_NLS_KOI8_U=y
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_KERNEL=y
 CONFIG_DEBUG_INFO=y
 # CONFIG_RCU_CPU_STALL_DETECTOR is not set
diff --git a/arch/arm/configs/shmobile_defconfig b/arch/arm/configs/shmobile_defconfig
index b7b714c..b3e18a2 100644
--- a/arch/arm/configs/shmobile_defconfig
+++ b/arch/arm/configs/shmobile_defconfig
@@ -207,7 +207,7 @@ CONFIG_NFS_V4_1=y
 CONFIG_ROOT_NFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 # CONFIG_ENABLE_WARN_DEPRECATED is not set
 # CONFIG_ENABLE_MUST_CHECK is not set
 # CONFIG_ARM_UNWIND is not set
diff --git a/arch/arm/configs/socfpga_defconfig b/arch/arm/configs/socfpga_defconfig
index 753f1a5..e277dc6 100644
--- a/arch/arm/configs/socfpga_defconfig
+++ b/arch/arm/configs/socfpga_defconfig
@@ -101,7 +101,7 @@ CONFIG_NFS_FS=y
 CONFIG_ROOT_NFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DETECT_HUNG_TASK=y
diff --git a/arch/arm/configs/stm32_defconfig b/arch/arm/configs/stm32_defconfig
index 1e5ec2a..44b6b03 100644
--- a/arch/arm/configs/stm32_defconfig
+++ b/arch/arm/configs/stm32_defconfig
@@ -61,7 +61,7 @@ CONFIG_STM32_DMA=y
 # CONFIG_DNOTIFY is not set
 # CONFIG_INOTIFY_USER is not set
 CONFIG_NLS=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 # CONFIG_ENABLE_WARN_DEPRECATED is not set
 # CONFIG_ENABLE_MUST_CHECK is not set
diff --git a/arch/arm/configs/sunxi_defconfig b/arch/arm/configs/sunxi_defconfig
index 81a1b92..e20ae39 100644
--- a/arch/arm/configs/sunxi_defconfig
+++ b/arch/arm/configs/sunxi_defconfig
@@ -146,6 +146,6 @@ CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_FS=y
 CONFIG_CRYPTO_DEV_SUN4I_SS=y
diff --git a/arch/arm/configs/tegra_defconfig b/arch/arm/configs/tegra_defconfig
index 3a36244..95eaa46 100644
--- a/arch/arm/configs/tegra_defconfig
+++ b/arch/arm/configs/tegra_defconfig
@@ -285,7 +285,7 @@ CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_FS=y
 CONFIG_MAGIC_SYSRQ=y
diff --git a/arch/arm/configs/u300_defconfig b/arch/arm/configs/u300_defconfig
index aaa95ab..7746006 100644
--- a/arch/arm/configs/u300_defconfig
+++ b/arch/arm/configs/u300_defconfig
@@ -63,7 +63,7 @@ CONFIG_VFAT_FS=y
 CONFIG_TMPFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_FS=y
 # CONFIG_SCHED_DEBUG is not set
diff --git a/arch/arm/configs/u8500_defconfig b/arch/arm/configs/u8500_defconfig
index a691d59..d2a3a67 100644
--- a/arch/arm/configs/u8500_defconfig
+++ b/arch/arm/configs/u8500_defconfig
@@ -129,7 +129,7 @@ CONFIG_NFS_FS=y
 CONFIG_ROOT_NFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_FS=y
 CONFIG_MAGIC_SYSRQ=y
diff --git a/arch/arm/configs/vt8500_v6_v7_defconfig b/arch/arm/configs/vt8500_v6_v7_defconfig
index 1bfaa7b..d5a2cc8 100644
--- a/arch/arm/configs/vt8500_v6_v7_defconfig
+++ b/arch/arm/configs/vt8500_v6_v7_defconfig
@@ -84,6 +84,6 @@ CONFIG_NFS_FS=y
 CONFIG_NFS_V3_ACL=y
 CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_KERNEL=y
 CONFIG_LOCKUP_DETECTOR=y
diff --git a/arch/arm/configs/xcep_defconfig b/arch/arm/configs/xcep_defconfig
index 721832f..5c8435d 100644
--- a/arch/arm/configs/xcep_defconfig
+++ b/arch/arm/configs/xcep_defconfig
@@ -85,7 +85,7 @@ CONFIG_NFS_V3=y
 CONFIG_NLS=m
 CONFIG_NLS_DEFAULT="utf8"
 CONFIG_NLS_UTF8=m
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_STRIP_ASM_SYMS=y
 CONFIG_DEBUG_KERNEL=y
 # CONFIG_SCHED_DEBUG is not set
diff --git a/arch/arm/configs/zx_defconfig b/arch/arm/configs/zx_defconfig
index ab683fb..e955730 100644
--- a/arch/arm/configs/zx_defconfig
+++ b/arch/arm/configs/zx_defconfig
@@ -98,7 +98,7 @@ CONFIG_TMPFS_POSIX_ACL=y
 CONFIG_NLS_CODEPAGE_936=y
 CONFIG_NLS_ISO8859_1=y
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_KERNEL=y
 CONFIG_DEBUG_INFO=y
diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
index a44ef99..b44e940 100644
--- a/arch/arm64/configs/defconfig
+++ b/arch/arm64/configs/defconfig
@@ -286,7 +286,7 @@ CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
 CONFIG_VIRTUALIZATION=y
 CONFIG_KVM=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_FS=y
 CONFIG_MAGIC_SYSRQ=y
diff --git a/arch/mips/configs/bcm47xx_defconfig b/arch/mips/configs/bcm47xx_defconfig
index 0db4eb3..f19fb76 100644
--- a/arch/mips/configs/bcm47xx_defconfig
+++ b/arch/mips/configs/bcm47xx_defconfig
@@ -75,7 +75,7 @@ CONFIG_USB_HCD_BCMA=y
 CONFIG_USB_HCD_SSB=y
 CONFIG_LEDS_TRIGGER_TIMER=y
 CONFIG_LEDS_TRIGGER_DEFAULT_ON=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_INFO_REDUCED=y
 CONFIG_STRIP_ASM_SYMS=y
diff --git a/arch/mips/configs/bmips_be_defconfig b/arch/mips/configs/bmips_be_defconfig
index 24dcb90..d065143 100644
--- a/arch/mips/configs/bmips_be_defconfig
+++ b/arch/mips/configs/bmips_be_defconfig
@@ -33,7 +33,7 @@ CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
 # CONFIG_STANDALONE is not set
 # CONFIG_PREVENT_FIRMWARE_BUILD is not set
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_BRCMSTB_GISB_ARB=y
 CONFIG_MTD=y
 CONFIG_MTD_CFI=y
diff --git a/arch/mips/configs/bmips_stb_defconfig b/arch/mips/configs/bmips_stb_defconfig
index 4eb5d6e..0800662 100644
--- a/arch/mips/configs/bmips_stb_defconfig
+++ b/arch/mips/configs/bmips_stb_defconfig
@@ -34,7 +34,7 @@ CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
 # CONFIG_STANDALONE is not set
 # CONFIG_PREVENT_FIRMWARE_BUILD is not set
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_BRCMSTB_GISB_ARB=y
 CONFIG_MTD=y
 CONFIG_MTD_CFI=y
diff --git a/arch/mips/configs/ci20_defconfig b/arch/mips/configs/ci20_defconfig
index 43e0ba2..bf164fe 100644
--- a/arch/mips/configs/ci20_defconfig
+++ b/arch/mips/configs/ci20_defconfig
@@ -148,7 +148,7 @@ CONFIG_NLS_ISO8859_15=y
 CONFIG_NLS_KOI8_R=y
 CONFIG_NLS_KOI8_U=y
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_STRIP_ASM_SYMS=y
 CONFIG_DEBUG_FS=y
diff --git a/arch/mips/configs/lemote2f_defconfig b/arch/mips/configs/lemote2f_defconfig
index d1f198b..6030606 100644
--- a/arch/mips/configs/lemote2f_defconfig
+++ b/arch/mips/configs/lemote2f_defconfig
@@ -405,7 +405,7 @@ CONFIG_NLS_ISO8859_15=m
 CONFIG_NLS_KOI8_R=m
 CONFIG_NLS_KOI8_U=m
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_FRAME_WARN=1024
 CONFIG_STRIP_ASM_SYMS=y
 CONFIG_DEBUG_FS=y
diff --git a/arch/mips/configs/loongson3_defconfig b/arch/mips/configs/loongson3_defconfig
index f8bf915c..e66df9f 100644
--- a/arch/mips/configs/loongson3_defconfig
+++ b/arch/mips/configs/loongson3_defconfig
@@ -330,7 +330,7 @@ CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_CODEPAGE_936=y
 CONFIG_NLS_ASCII=y
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_FRAME_WARN=1024
 CONFIG_STRIP_ASM_SYMS=y
 CONFIG_MAGIC_SYSRQ=y
diff --git a/arch/mips/configs/nlm_xlp_defconfig b/arch/mips/configs/nlm_xlp_defconfig
index b3d1d37..efd6877 100644
--- a/arch/mips/configs/nlm_xlp_defconfig
+++ b/arch/mips/configs/nlm_xlp_defconfig
@@ -554,7 +554,7 @@ CONFIG_NLS_ISO8859_14=m
 CONFIG_NLS_ISO8859_15=m
 CONFIG_NLS_KOI8_R=m
 CONFIG_NLS_KOI8_U=m
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 # CONFIG_ENABLE_WARN_DEPRECATED is not set
 # CONFIG_ENABLE_MUST_CHECK is not set
 CONFIG_FRAME_WARN=1024
diff --git a/arch/mips/configs/nlm_xlr_defconfig b/arch/mips/configs/nlm_xlr_defconfig
index 3d8016d..c913c70 100644
--- a/arch/mips/configs/nlm_xlr_defconfig
+++ b/arch/mips/configs/nlm_xlr_defconfig
@@ -514,7 +514,7 @@ CONFIG_NLS_ISO8859_14=m
 CONFIG_NLS_ISO8859_15=m
 CONFIG_NLS_KOI8_R=m
 CONFIG_NLS_KOI8_U=m
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 # CONFIG_ENABLE_WARN_DEPRECATED is not set
 # CONFIG_ENABLE_MUST_CHECK is not set
 CONFIG_UNUSED_SYMBOLS=y
diff --git a/arch/mips/configs/pistachio_defconfig b/arch/mips/configs/pistachio_defconfig
index 8b74291..022907e 100644
--- a/arch/mips/configs/pistachio_defconfig
+++ b/arch/mips/configs/pistachio_defconfig
@@ -299,7 +299,7 @@ CONFIG_NLS_DEFAULT="utf8"
 CONFIG_NLS_CODEPAGE_437=m
 CONFIG_NLS_ASCII=m
 CONFIG_NLS_ISO8859_1=m
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE=0
diff --git a/arch/mips/configs/qi_lb60_defconfig b/arch/mips/configs/qi_lb60_defconfig
index d7bb8cc..e9dd20a 100644
--- a/arch/mips/configs/qi_lb60_defconfig
+++ b/arch/mips/configs/qi_lb60_defconfig
@@ -172,7 +172,7 @@ CONFIG_NLS_ISO8859_15=y
 CONFIG_NLS_KOI8_R=y
 CONFIG_NLS_KOI8_U=y
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_STRIP_ASM_SYMS=y
 CONFIG_READABLE_ASM=y
diff --git a/arch/mips/configs/rt305x_defconfig b/arch/mips/configs/rt305x_defconfig
index d14ae2f..005754c 100644
--- a/arch/mips/configs/rt305x_defconfig
+++ b/arch/mips/configs/rt305x_defconfig
@@ -145,7 +145,7 @@ CONFIG_JFFS2_COMPRESSION_OPTIONS=y
 CONFIG_SQUASHFS=y
 # CONFIG_SQUASHFS_ZLIB is not set
 CONFIG_SQUASHFS_XZ=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 # CONFIG_ENABLE_MUST_CHECK is not set
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_STRIP_ASM_SYMS=y
diff --git a/arch/mips/configs/xway_defconfig b/arch/mips/configs/xway_defconfig
index 8987846..c293c78 100644
--- a/arch/mips/configs/xway_defconfig
+++ b/arch/mips/configs/xway_defconfig
@@ -143,7 +143,7 @@ CONFIG_JFFS2_COMPRESSION_OPTIONS=y
 CONFIG_SQUASHFS=y
 # CONFIG_SQUASHFS_ZLIB is not set
 CONFIG_SQUASHFS_XZ=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 # CONFIG_ENABLE_MUST_CHECK is not set
 CONFIG_STRIP_ASM_SYMS=y
 CONFIG_DEBUG_FS=y
diff --git a/arch/parisc/configs/generic-64bit_defconfig b/arch/parisc/configs/generic-64bit_defconfig
index e945c08..df76193 100644
--- a/arch/parisc/configs/generic-64bit_defconfig
+++ b/arch/parisc/configs/generic-64bit_defconfig
@@ -279,7 +279,7 @@ CONFIG_NLS_ASCII=m
 CONFIG_NLS_ISO8859_1=m
 CONFIG_NLS_ISO8859_2=m
 CONFIG_NLS_UTF8=m
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_STRIP_ASM_SYMS=y
 CONFIG_UNUSED_SYMBOLS=y
 CONFIG_DEBUG_FS=y
diff --git a/arch/powerpc/configs/40x/virtex_defconfig b/arch/powerpc/configs/40x/virtex_defconfig
index bcb0c4d..bb076ef 100644
--- a/arch/powerpc/configs/40x/virtex_defconfig
+++ b/arch/powerpc/configs/40x/virtex_defconfig
@@ -72,7 +72,7 @@ CONFIG_CRC_CCITT=y
 CONFIG_FONTS=y
 CONFIG_FONT_8x8=y
 CONFIG_FONT_8x16=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_KERNEL=y
 # CONFIG_CRYPTO_ANSI_CPRNG is not set
diff --git a/arch/powerpc/configs/44x/virtex5_defconfig b/arch/powerpc/configs/44x/virtex5_defconfig
index 53d0300..f5cf657 100644
--- a/arch/powerpc/configs/44x/virtex5_defconfig
+++ b/arch/powerpc/configs/44x/virtex5_defconfig
@@ -71,7 +71,7 @@ CONFIG_CRC_CCITT=y
 CONFIG_FONTS=y
 CONFIG_FONT_8x8=y
 CONFIG_FONT_8x16=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_KERNEL=y
 # CONFIG_CRYPTO_ANSI_CPRNG is not set
diff --git a/arch/powerpc/configs/44x/warp_defconfig b/arch/powerpc/configs/44x/warp_defconfig
index ee43437..e925959 100644
--- a/arch/powerpc/configs/44x/warp_defconfig
+++ b/arch/powerpc/configs/44x/warp_defconfig
@@ -93,7 +93,7 @@ CONFIG_NLS_ISO8859_15=y
 CONFIG_NLS_UTF8=y
 CONFIG_CRC_CCITT=y
 CONFIG_CRC_T10DIF=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_FS=y
 CONFIG_MAGIC_SYSRQ=y
diff --git a/arch/powerpc/configs/52xx/cm5200_defconfig b/arch/powerpc/configs/52xx/cm5200_defconfig
index 19fad0e..3cc0a427 100644
--- a/arch/powerpc/configs/52xx/cm5200_defconfig
+++ b/arch/powerpc/configs/52xx/cm5200_defconfig
@@ -74,7 +74,7 @@ CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DETECT_HUNG_TASK=y
 # CONFIG_DEBUG_BUGVERBOSE is not set
 CONFIG_CRYPTO_ECB=y
diff --git a/arch/powerpc/configs/52xx/lite5200b_defconfig b/arch/powerpc/configs/52xx/lite5200b_defconfig
index 5f40ba9..5a24f60 100644
--- a/arch/powerpc/configs/52xx/lite5200b_defconfig
+++ b/arch/powerpc/configs/52xx/lite5200b_defconfig
@@ -60,7 +60,7 @@ CONFIG_TMPFS=y
 CONFIG_NFS_FS=y
 CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DETECT_HUNG_TASK=y
 # CONFIG_DEBUG_BUGVERBOSE is not set
diff --git a/arch/powerpc/configs/52xx/motionpro_defconfig b/arch/powerpc/configs/52xx/motionpro_defconfig
index 909e185..e7ef6c8 100644
--- a/arch/powerpc/configs/52xx/motionpro_defconfig
+++ b/arch/powerpc/configs/52xx/motionpro_defconfig
@@ -86,7 +86,7 @@ CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DETECT_HUNG_TASK=y
 # CONFIG_DEBUG_BUGVERBOSE is not set
diff --git a/arch/powerpc/configs/52xx/tqm5200_defconfig b/arch/powerpc/configs/52xx/tqm5200_defconfig
index efab838..5a91b50 100644
--- a/arch/powerpc/configs/52xx/tqm5200_defconfig
+++ b/arch/powerpc/configs/52xx/tqm5200_defconfig
@@ -88,7 +88,7 @@ CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DETECT_HUNG_TASK=y
 # CONFIG_DEBUG_BUGVERBOSE is not set
diff --git a/arch/powerpc/configs/gamecube_defconfig b/arch/powerpc/configs/gamecube_defconfig
index 6c6c60f..d4dbe36 100644
--- a/arch/powerpc/configs/gamecube_defconfig
+++ b/arch/powerpc/configs/gamecube_defconfig
@@ -92,7 +92,7 @@ CONFIG_CIFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
 CONFIG_CRC_CCITT=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_SPINLOCK=y
 CONFIG_DEBUG_MUTEXES=y
 CONFIG_LATENCYTOP=y
diff --git a/arch/powerpc/configs/mpc5200_defconfig b/arch/powerpc/configs/mpc5200_defconfig
index 9fd041b..4b7dc33 100644
--- a/arch/powerpc/configs/mpc5200_defconfig
+++ b/arch/powerpc/configs/mpc5200_defconfig
@@ -128,7 +128,7 @@ CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_KERNEL=y
 CONFIG_DETECT_HUNG_TASK=y
diff --git a/arch/powerpc/configs/pasemi_defconfig b/arch/powerpc/configs/pasemi_defconfig
index 8f94782..b025444 100644
--- a/arch/powerpc/configs/pasemi_defconfig
+++ b/arch/powerpc/configs/pasemi_defconfig
@@ -171,7 +171,7 @@ CONFIG_NFSD_V4=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
 CONFIG_CRC_CCITT=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_FS=y
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_KERNEL=y
diff --git a/arch/powerpc/configs/wii_defconfig b/arch/powerpc/configs/wii_defconfig
index 34eaf52..2d9ee18 100644
--- a/arch/powerpc/configs/wii_defconfig
+++ b/arch/powerpc/configs/wii_defconfig
@@ -113,7 +113,7 @@ CONFIG_CIFS=m
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
 CONFIG_CRC_CCITT=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_SPINLOCK=y
 CONFIG_DEBUG_MUTEXES=y
diff --git a/arch/s390/configs/default_defconfig b/arch/s390/configs/default_defconfig
index 0ac42cc..5e3e73e 100644
--- a/arch/s390/configs/default_defconfig
+++ b/arch/s390/configs/default_defconfig
@@ -534,7 +534,7 @@ CONFIG_NLS_ISO8859_1=m
 CONFIG_NLS_ISO8859_15=m
 CONFIG_NLS_UTF8=m
 CONFIG_DLM=m
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DYNAMIC_DEBUG=y
 CONFIG_DEBUG_INFO=y
 CONFIG_FRAME_WARN=1024
diff --git a/arch/s390/configs/gcov_defconfig b/arch/s390/configs/gcov_defconfig
index a31dcd5..aedc828 100644
--- a/arch/s390/configs/gcov_defconfig
+++ b/arch/s390/configs/gcov_defconfig
@@ -528,7 +528,7 @@ CONFIG_NLS_ISO8859_1=m
 CONFIG_NLS_ISO8859_15=m
 CONFIG_NLS_UTF8=m
 CONFIG_DLM=m
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 # CONFIG_ENABLE_MUST_CHECK is not set
 CONFIG_FRAME_WARN=1024
diff --git a/arch/s390/configs/performance_defconfig b/arch/s390/configs/performance_defconfig
index 7b73bf3..b5e9dc1 100644
--- a/arch/s390/configs/performance_defconfig
+++ b/arch/s390/configs/performance_defconfig
@@ -528,7 +528,7 @@ CONFIG_NLS_ISO8859_1=m
 CONFIG_NLS_ISO8859_15=m
 CONFIG_NLS_UTF8=m
 CONFIG_DLM=m
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 # CONFIG_ENABLE_MUST_CHECK is not set
 CONFIG_FRAME_WARN=1024
diff --git a/arch/s390/configs/zfcpdump_defconfig b/arch/s390/configs/zfcpdump_defconfig
index 1719843..ef2a9b6 100644
--- a/arch/s390/configs/zfcpdump_defconfig
+++ b/arch/s390/configs/zfcpdump_defconfig
@@ -56,7 +56,7 @@ CONFIG_RAW_DRIVER=y
 # CONFIG_INOTIFY_USER is not set
 CONFIG_CONFIGFS_FS=y
 # CONFIG_MISC_FILESYSTEMS is not set
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_FS=y
 CONFIG_DEBUG_KERNEL=y
diff --git a/arch/sh/configs/edosk7760_defconfig b/arch/sh/configs/edosk7760_defconfig
index e1077a0..e588da2 100644
--- a/arch/sh/configs/edosk7760_defconfig
+++ b/arch/sh/configs/edosk7760_defconfig
@@ -109,7 +109,7 @@ CONFIG_NLS_ASCII=y
 CONFIG_NLS_ISO8859_1=y
 CONFIG_NLS_ISO8859_15=y
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 # CONFIG_ENABLE_MUST_CHECK is not set
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_UNUSED_SYMBOLS=y
diff --git a/arch/sh/configs/sdk7786_defconfig b/arch/sh/configs/sdk7786_defconfig
index e7e56a4..2e12997 100644
--- a/arch/sh/configs/sdk7786_defconfig
+++ b/arch/sh/configs/sdk7786_defconfig
@@ -216,7 +216,7 @@ CONFIG_NLS_ASCII=m
 CONFIG_NLS_ISO8859_1=y
 CONFIG_NLS_ISO8859_15=m
 CONFIG_NLS_UTF8=m
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 # CONFIG_ENABLE_WARN_DEPRECATED is not set
 # CONFIG_ENABLE_MUST_CHECK is not set
 CONFIG_MAGIC_SYSRQ=y
diff --git a/arch/sh/configs/se7722_defconfig b/arch/sh/configs/se7722_defconfig
index ae998c7..09aac57 100644
--- a/arch/sh/configs/se7722_defconfig
+++ b/arch/sh/configs/se7722_defconfig
@@ -53,7 +53,7 @@ CONFIG_EXT3_FS=y
 CONFIG_PROC_KCORE=y
 CONFIG_TMPFS=y
 CONFIG_HUGETLBFS=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 # CONFIG_ENABLE_MUST_CHECK is not set
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_FS=y
diff --git a/arch/sh/configs/sh7785lcr_32bit_defconfig b/arch/sh/configs/sh7785lcr_32bit_defconfig
index 9bdcf72..bdb7783 100644
--- a/arch/sh/configs/sh7785lcr_32bit_defconfig
+++ b/arch/sh/configs/sh7785lcr_32bit_defconfig
@@ -144,7 +144,7 @@ CONFIG_NFSD_V3=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_CODEPAGE_932=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 # CONFIG_ENABLE_MUST_CHECK is not set
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_KERNEL=y
diff --git a/arch/sh/configs/urquell_defconfig b/arch/sh/configs/urquell_defconfig
index 1e843db..795afb5 100644
--- a/arch/sh/configs/urquell_defconfig
+++ b/arch/sh/configs/urquell_defconfig
@@ -143,7 +143,7 @@ CONFIG_ROOT_NFS=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_CODEPAGE_932=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 # CONFIG_ENABLE_WARN_DEPRECATED is not set
 # CONFIG_ENABLE_MUST_CHECK is not set
 CONFIG_DEBUG_FS=y
diff --git a/arch/sparc/configs/sparc64_defconfig b/arch/sparc/configs/sparc64_defconfig
index 04920ab..d699009 100644
--- a/arch/sparc/configs/sparc64_defconfig
+++ b/arch/sparc/configs/sparc64_defconfig
@@ -203,7 +203,7 @@ CONFIG_EXT3_FS_SECURITY=y
 CONFIG_PROC_KCORE=y
 CONFIG_TMPFS=y
 CONFIG_HUGETLBFS=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 # CONFIG_ENABLE_WARN_DEPRECATED is not set
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_KERNEL=y
diff --git a/arch/x86/configs/i386_defconfig b/arch/x86/configs/i386_defconfig
index 265901a..a3a7a81 100644
--- a/arch/x86/configs/i386_defconfig
+++ b/arch/x86/configs/i386_defconfig
@@ -286,7 +286,7 @@ CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ASCII=y
 CONFIG_NLS_ISO8859_1=y
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 # CONFIG_ENABLE_WARN_DEPRECATED is not set
 CONFIG_FRAME_WARN=1024
 CONFIG_MAGIC_SYSRQ=y
diff --git a/arch/x86/configs/x86_64_defconfig b/arch/x86/configs/x86_64_defconfig
index 4f404a6..0250dbd 100644
--- a/arch/x86/configs/x86_64_defconfig
+++ b/arch/x86/configs/x86_64_defconfig
@@ -284,7 +284,7 @@ CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ASCII=y
 CONFIG_NLS_ISO8859_1=y
 CONFIG_NLS_UTF8=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 # CONFIG_ENABLE_WARN_DEPRECATED is not set
 CONFIG_MAGIC_SYSRQ=y
 # CONFIG_UNUSED_SYMBOLS is not set
diff --git a/arch/xtensa/configs/audio_kc705_defconfig b/arch/xtensa/configs/audio_kc705_defconfig
index c4904db..bc0e69f 100644
--- a/arch/xtensa/configs/audio_kc705_defconfig
+++ b/arch/xtensa/configs/audio_kc705_defconfig
@@ -123,7 +123,7 @@ CONFIG_ROOT_NFS=y
 CONFIG_SUNRPC_DEBUG=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DYNAMIC_DEBUG=y
 CONFIG_DEBUG_INFO=y
 CONFIG_MAGIC_SYSRQ=y
diff --git a/arch/xtensa/configs/generic_kc705_defconfig b/arch/xtensa/configs/generic_kc705_defconfig
index f4b7b38..6adabfa 100644
--- a/arch/xtensa/configs/generic_kc705_defconfig
+++ b/arch/xtensa/configs/generic_kc705_defconfig
@@ -111,7 +111,7 @@ CONFIG_ROOT_NFS=y
 CONFIG_SUNRPC_DEBUG=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DYNAMIC_DEBUG=y
 CONFIG_DEBUG_INFO=y
 CONFIG_MAGIC_SYSRQ=y
diff --git a/arch/xtensa/configs/nommu_kc705_defconfig b/arch/xtensa/configs/nommu_kc705_defconfig
index 337d5ba..0727336 100644
--- a/arch/xtensa/configs/nommu_kc705_defconfig
+++ b/arch/xtensa/configs/nommu_kc705_defconfig
@@ -107,7 +107,7 @@ CONFIG_ROOT_NFS=y
 CONFIG_SUNRPC_DEBUG=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DYNAMIC_DEBUG=y
 CONFIG_DEBUG_INFO=y
 # CONFIG_FRAME_POINTER is not set
diff --git a/arch/xtensa/configs/smp_lx200_defconfig b/arch/xtensa/configs/smp_lx200_defconfig
index 22eeacb..fb09f54 100644
--- a/arch/xtensa/configs/smp_lx200_defconfig
+++ b/arch/xtensa/configs/smp_lx200_defconfig
@@ -115,7 +115,7 @@ CONFIG_ROOT_NFS=y
 CONFIG_SUNRPC_DEBUG=y
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ISO8859_1=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_DYNAMIC_DEBUG=y
 CONFIG_DEBUG_INFO=y
 CONFIG_MAGIC_SYSRQ=y
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index bfbf284..18dee96 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1040,8 +1040,45 @@ static inline void boot_delay_msec(int level)
 }
 #endif
 
-static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME);
-module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
+static int printk_time = CONFIG_PRINTK_TIME;
+
+static int printk_time_param_set(const char *val,
+				 const struct kernel_param *kp)
+{
+	char *param = strstrip((char *)val);
+
+	if (strlen(param) != 1)
+		return -EINVAL;
+
+	switch (param[0]) {
+	/* 0/N/n = disabled */
+	case '0':
+	case 'N':
+	case 'n':
+		printk_time = 0;
+		break;
+	/* 1/Y/y = local clock */
+	case '1':
+	case 'Y':
+	case 'y':
+		printk_time = 1;
+		break;
+	default:
+		pr_warn("printk: invalid timestamp value\n");
+		return -EINVAL;
+		break;
+	}
+
+	pr_info("printk: timestamp set to %d.\n", printk_time);
+	return 0;
+}
+
+static struct kernel_param_ops printk_time_param_ops = {
+	.set = printk_time_param_set,
+	.get = param_get_int,
+};
+
+module_param_cb(time, &printk_time_param_ops, &printk_time, S_IRUGO);
 
 static size_t print_time(u64 ts, char *buf)
 {
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 1e9a607..774aa38 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1,7 +1,9 @@
 menu "printk and dmesg options"
 
 config PRINTK_TIME
-	bool "Show timing information on printks"
+	int "Show timing information on printks (0-1)"
+	range 0 1
+	default "0"
 	depends on PRINTK
 	help
 	  Selecting this option causes time stamps of the printk()
@@ -10,7 +12,8 @@ config PRINTK_TIME
 
 	  The timestamp is always recorded internally, and exported
 	  to /dev/kmsg. This flag just specifies if the timestamp should
-	  be included, not that the timestamp is recorded.
+	  be included, not that the timestamp is recorded. 0 disables the
+	  timestamp and 1 uses the local clock.
 
 	  The behavior is also controlled by the kernel command line
 	  parameter printk.time=1. See Documentation/kernel-parameters.txt
diff --git a/tools/testing/selftests/rcutorture/configs/lock/CFcommon b/tools/testing/selftests/rcutorture/configs/lock/CFcommon
index e372dc2..779f984 100644
--- a/tools/testing/selftests/rcutorture/configs/lock/CFcommon
+++ b/tools/testing/selftests/rcutorture/configs/lock/CFcommon
@@ -1,2 +1,2 @@
 CONFIG_LOCK_TORTURE_TEST=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/CFcommon b/tools/testing/selftests/rcutorture/configs/rcu/CFcommon
index f824b4c..7461db3 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/CFcommon
+++ b/tools/testing/selftests/rcutorture/configs/rcu/CFcommon
@@ -1,5 +1,5 @@
 CONFIG_RCU_TORTURE_TEST=y
-CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_TIME=1
 CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
 CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
 CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y
-- 
1.7.9.3

Re: [PATCH 1/2] lib, switch CONFIG_PRINTK_TIME to int

[Petr Mladek]

On Fri 2016-04-22 08:03:08, Prarit Bhargava wrote:
> CONFIG_PRINTK_TIME is a bool and in order to add timestamp options for
> the monotonic and real time clock it must be expanded to an int.
> 
> diff --git a/arch/x86/configs/x86_64_defconfig b/arch/x86/configs/x86_64_defconfig
> index 4f404a6..0250dbd 100644
> --- a/arch/x86/configs/x86_64_defconfig
> +++ b/arch/x86/configs/x86_64_defconfig
> @@ -284,7 +284,7 @@ CONFIG_NLS_CODEPAGE_437=y
>  CONFIG_NLS_ASCII=y
>  CONFIG_NLS_ISO8859_1=y
>  CONFIG_NLS_UTF8=y
> -CONFIG_PRINTK_TIME=y
> +CONFIG_PRINTK_TIME=1
>  # CONFIG_ENABLE_WARN_DEPRECATED is not set
>  CONFIG_MAGIC_SYSRQ=y
>  # CONFIG_UNUSED_SYMBOLS is not set
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 1e9a607..774aa38 100644
[...]
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -1,7 +1,9 @@
>  menu "printk and dmesg options"
>  
>  config PRINTK_TIME
> -	bool "Show timing information on printks"
> +	int "Show timing information on printks (0-1)"
> +	range 0 1
> +	default "0"

I get "0" as the default when running "make" with this patch:

$>> make oldconfig
scripts/kconfig/conf  --oldconfig Kconfig
.config:3463:warning: symbol value 'y' invalid for PRINTK_TIME
*
* Restart config...
*
*
* printk and dmesg options
*
Show timing information on printks (0-3) (PRINTK_TIME) [0] (NEW) 
                                                       ^^^

And it really writes 0 into .config:

$>> grep PRINTK_TIME .config
CONFIG_PRINTK_TIME=0

It seems that arch/x86/configs/x86_64_defconfig is used only when
you call "make defconfig"

Hmm, this might be surprising and annoying for many people. I would
suggest to make "1" as the default value and remove the default from
all that defconfigs. It is default on almost all systems and it is
why people would expect.

Best Regards,
Petr

[PATCH 2/2] printk, allow different timestamps for printk.time

[Prarit Bhargava]

Over the past years I've seen many reports of bugs that include
time-stamped kernel logs (enabled when CONFIG_PRINTK_TIME=y or
print.time=1 is specified as a kernel parameter) that do not align
with either external time stamped logs or /var/log/messages.  This
also makes determining the time of a failure difficult in cases where
/var/log/messages is unavailable.

For example,

[root@intel-wildcatpass-06 ~]# date; echo "Hello!" > /dev/kmsg ; date
Thu Dec 17 13:58:31 EST 2015
Thu Dec 17 13:58:31 EST 2015

which displays

[83973.768912] Hello!

on the serial console.

Running a script to convert this to the stamped time,

[root@intel-wildcatpass-06 ~]# ./human.sh  | tail -1
[Thu Dec 17 13:59:57 2015] Hello!

which is already off by 1 minute and 26 seconds off after ~24 hours of
uptime.

This occurs because the time stamp is obtained from a call to
local_clock() which (on x86) is a direct call to the hardware.  These
hardware clock reads are not modified by the standard ntp or ptp protocol,
while the other timestamps are, and that results in situations external
time sources are further and further offset from the kernel log
timestamps.

This patch introduces printk.time=[0-3] allowing a user to specify an adjusted
clock to use with printk timestamps.  The hardware clock, or the existing
functionality, is preserved by default.

Real clock & 32-bit systems:  Selecting the real clock printk timestamp may
lead to unlikely situations where a timestamp is wrong because the real time
offset is read without the protection of a sequence lock in the call to
ktime_get_log_ts() in printk_get_ts().

[v2]: use NMI safe timekeeping access functions
[v3]: use tglx's ktime_get_log_ts() suggestion to get monotonic & real clocks
[v4]: Fix kernel parameters
[v5]: Modify configs to accept [0-3]
[v6]: Implement Kconfig changes from Petr Mladek, fix CONFIG_PRINTK_TIME=0
and dmesg bug

Cc: Cc: Petr Mladek <pmladek@suse.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Xunlei Pang <pang.xunlei@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Baolin Wang <baolin.wang@linaro.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Petr Mladek <pmladek@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Vasily Averin <vvs@virtuozzo.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
---
 Documentation/kernel-parameters.txt |    6 ++++--
 include/linux/timekeeping.h         |    1 +
 kernel/printk/printk.c              |   35 +++++++++++++++++++++++++++++++++--
 kernel/time/timekeeping.c           |   13 +++++++++++++
 lib/Kconfig.debug                   |    7 ++++---
 5 files changed, 55 insertions(+), 7 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 79c3e28..95cd7fe 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -3111,8 +3111,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
 			default: disabled
 
-	printk.time=	Show timing data prefixed to each printk message line
-			Format: <string>  (1/Y/y=enable, 0/N/n=disable)
+	printk.time=	Show timestamp prefixed to each printk message line
+			Format: <string>
+				(0/N/n = disable, 1/Y/y = local clock,
+				2 = monotonic clock, 3 = real clock)
 
 	processor.max_cstate=	[HW,ACPI]
 			Limit processor to maximum C-state
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index 96f37be..9b57867 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -233,6 +233,7 @@ static inline u64 ktime_get_raw_ns(void)
 
 extern u64 ktime_get_mono_fast_ns(void);
 extern u64 ktime_get_raw_fast_ns(void);
+extern u64 ktime_get_log_ts(u64 *offset_real);
 
 /*
  * Timespec interfaces utilizing the ktime based ones
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 18dee96..48a8214 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -424,6 +424,8 @@ static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len,
 	return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len);
 }
 
+static u64 printk_get_ts(void);
+
 /* insert record into the buffer, discard old ones, update heads */
 static int log_store(int facility, int level,
 		     enum log_flags flags, u64 ts_nsec,
@@ -472,7 +474,7 @@ static int log_store(int facility, int level,
 	if (ts_nsec > 0)
 		msg->ts_nsec = ts_nsec;
 	else
-		msg->ts_nsec = local_clock();
+		msg->ts_nsec = printk_get_ts();
 	memset(log_dict(msg) + dict_len, 0, pad_len);
 	msg->len = size;
 
@@ -1042,6 +1044,12 @@ static inline void boot_delay_msec(int level)
 
 static int printk_time = CONFIG_PRINTK_TIME;
 
+/*
+ * Real clock & 32-bit systems:  Selecting the real clock printk timestamp may
+ * lead to unlikely situations where a timestamp is wrong because the real time
+ * offset is read without the protection of a sequence lock in the call to
+ * ktime_get_log_ts() in printk_get_ts() below.
+ */
 static int printk_time_param_set(const char *val,
 				 const struct kernel_param *kp)
 {
@@ -1063,6 +1071,14 @@ static int printk_time_param_set(const char *val,
 	case 'y':
 		printk_time = 1;
 		break;
+	/* 2 = monotonic clock */
+	case '2':
+		printk_time = 2;
+		break;
+	/* 3 = real clock */
+	case '3':
+		printk_time = 3;
+		break;
 	default:
 		pr_warn("printk: invalid timestamp value\n");
 		return -EINVAL;
@@ -1080,6 +1096,21 @@ static struct kernel_param_ops printk_time_param_ops = {
 
 module_param_cb(time, &printk_time_param_ops, &printk_time, S_IRUGO);
 
+static u64 printk_get_ts(void)
+{
+	u64 mono, offset_real;
+
+	if (printk_time <= 1)
+		return local_clock();
+
+	mono = ktime_get_log_ts(&offset_real);
+
+	if (printk_time == 2)
+		return mono;
+
+	return mono + offset_real;
+}
+
 static size_t print_time(u64 ts, char *buf)
 {
 	unsigned long rem_nsec;
@@ -1598,7 +1629,7 @@ static bool cont_add(int facility, int level, const char *text, size_t len)
 		cont.facility = facility;
 		cont.level = level;
 		cont.owner = current;
-		cont.ts_nsec = local_clock();
+		cont.ts_nsec = printk_get_ts();
 		cont.flags = 0;
 		cont.cons = 0;
 		cont.flushed = false;
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 479d25c..feb1995 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -43,6 +43,7 @@ static struct {
 
 static DEFINE_RAW_SPINLOCK(timekeeper_lock);
 static struct timekeeper shadow_timekeeper;
+static int timekeeping_active;
 
 /**
  * struct tk_fast - NMI safe timekeeper
@@ -419,6 +420,16 @@ u64 ktime_get_raw_fast_ns(void)
 }
 EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
 
+u64 ktime_get_log_ts(u64 *offset_real)
+{
+	*offset_real = ktime_to_ns(tk_core.timekeeper.offs_real);
+
+	if (timekeeping_active)
+		return ktime_get_mono_fast_ns();
+	else
+		return local_clock();
+}
+
 /* Suspend-time cycles value for halted fast timekeeper. */
 static cycle_t cycles_at_suspend;
 
@@ -1503,6 +1514,8 @@ void __init timekeeping_init(void)
 
 	write_seqcount_end(&tk_core.seq);
 	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+
+	timekeeping_active = 1;
 }
 
 /* time in seconds when suspend began for persistent clock */
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 774aa38..3197262 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1,8 +1,8 @@
 menu "printk and dmesg options"
 
 config PRINTK_TIME
-	int "Show timing information on printks (0-1)"
-	range 0 1
+	int "Show timing information on printks (0-3)"
+	range 0 3
 	default "0"
 	depends on PRINTK
 	help
@@ -13,7 +13,8 @@ config PRINTK_TIME
 	  The timestamp is always recorded internally, and exported
 	  to /dev/kmsg. This flag just specifies if the timestamp should
 	  be included, not that the timestamp is recorded. 0 disables the
-	  timestamp and 1 uses the local clock.
+	  timestamp and 1 uses the local clock, 2 uses the monotonic clock, and
+	  3 uses real clock.
 
 	  The behavior is also controlled by the kernel command line
 	  parameter printk.time=1. See Documentation/kernel-parameters.txt
-- 
1.7.9.3

Re: [PATCH 2/2] printk, allow different timestamps for printk.time

[Andrew Morton]

On Fri, 22 Apr 2016 08:03:09 -0400 Prarit Bhargava <prarit@redhat.com> wrote:

> Over the past years I've seen many reports of bugs that include
> time-stamped kernel logs (enabled when CONFIG_PRINTK_TIME=y or
> print.time=1 is specified as a kernel parameter) that do not align
> with either external time stamped logs or /var/log/messages.  This
> also makes determining the time of a failure difficult in cases where
> /var/log/messages is unavailable.
> 
> For example,
> 
> [root@intel-wildcatpass-06 ~]# date; echo "Hello!" > /dev/kmsg ; date
> Thu Dec 17 13:58:31 EST 2015
> Thu Dec 17 13:58:31 EST 2015
> 
> which displays
> 
> [83973.768912] Hello!
> 
> on the serial console.
> 
> Running a script to convert this to the stamped time,
> 
> [root@intel-wildcatpass-06 ~]# ./human.sh  | tail -1
> [Thu Dec 17 13:59:57 2015] Hello!
> 
> which is already off by 1 minute and 26 seconds off after ~24 hours of
> uptime.
> 
> This occurs because the time stamp is obtained from a call to
> local_clock() which (on x86) is a direct call to the hardware.  These
> hardware clock reads are not modified by the standard ntp or ptp protocol,
> while the other timestamps are, and that results in situations external
> time sources are further and further offset from the kernel log
> timestamps.
> 
> This patch introduces printk.time=[0-3] allowing a user to specify an adjusted
> clock to use with printk timestamps.  The hardware clock, or the existing
> functionality, is preserved by default.
> 
> Real clock & 32-bit systems:  Selecting the real clock printk timestamp may
> lead to unlikely situations where a timestamp is wrong because the real time
> offset is read without the protection of a sequence lock in the call to
> ktime_get_log_ts() in printk_get_ts().

Looks OK to me.  Timekeeping stuff makes my head spin nowadays but I
trust you've sorted out the obvious deadlock/reentrancy/etc issues. 
I'll toss it in for some testing.

> @@ -1042,6 +1044,12 @@ static inline void boot_delay_msec(int level)
>  
>  static int printk_time = CONFIG_PRINTK_TIME;
>  
> +/*
> + * Real clock & 32-bit systems:  Selecting the real clock printk timestamp may
> + * lead to unlikely situations where a timestamp is wrong because the real time
> + * offset is read without the protection of a sequence lock in the call to
> + * ktime_get_log_ts() in printk_get_ts() below.
> + */
>  static int printk_time_param_set(const char *val,
>  				 const struct kernel_param *kp)
>  {
> @@ -1063,6 +1071,14 @@ static int printk_time_param_set(const char *val,
>  	case 'y':
>  		printk_time = 1;
>  		break;
> +	/* 2 = monotonic clock */
> +	case '2':
> +		printk_time = 2;
> +		break;
> +	/* 3 = real clock */
> +	case '3':
> +		printk_time = 3;
> +		break;

Maybe it's time to enumerate these values.

>  	default:
>  		pr_warn("printk: invalid timestamp value\n");
>  		return -EINVAL;
> @@ -1080,6 +1096,21 @@ static struct kernel_param_ops printk_time_param_ops = {
>  
>  module_param_cb(time, &printk_time_param_ops, &printk_time, S_IRUGO);
>  
> +static u64 printk_get_ts(void)
> +{
> +	u64 mono, offset_real;
> +
> +	if (printk_time <= 1)
> +		return local_clock();
> +
> +	mono = ktime_get_log_ts(&offset_real);
> +
> +	if (printk_time == 2)
> +		return mono;
> +
> +	return mono + offset_real;
> +}

Because the magic constants set a bad example for any children in the
audience.