[PATCH v4 0/3] bootconfig: Support embedding a bootconfig in kernel for non initrd boot

[PATCH v4 0/3] bootconfig: Support embedding a bootconfig in kernel for non initrd boot

[Masami Hiramatsu]

Hi,

Here are the 4th version of the patchset to enable kernel embedded bootconfig
for non-initrd kernel boot environment. I've fixed Makefile to determine
update by checking the contents of embedding bootconfig file with filechk macro.
Thanks Masahiro! Here is the previous version [1] (sorry, I missed to update the
version tag in that series)

[1] https://lore.kernel.org/all/164724890153.731226.1478494969800777757.stgit@devnote2/T/#u

You can embed a bootconfig file into the kernel as a default bootconfig,
which will be used if there is no initrd or no bootconfig is attached to initrd. 

This needs 2 options: CONFIG_EMBED_BOOT_CONFIG=y and set the file
path to CONFIG_EMBED_BOOT_CONFIG_FILE. Even if you embed the bootconfig file
to the kernel, it will not be enabled unless you pass "bootconfig" kernel
command line option at boot. Moreover, since this is just a "default"
bootconfig, you can override it with a new bootconfig if you attach another
bootconfig to the initrd (if possible).
CONFIG_EMBED_BOOT_CONFIG_FILE can take both absolute and relative path, but
to simplify and make it independent from the build environment, I recommend
you to use an absolute path for that.

This is requested by Padmanabha at the below thread[2];

[2] https://lore.kernel.org/all/20220307184011.GA2570@pswork/T/#u


KNOWN ISSUE:

According to the report from Padmanabha[3], the embedded bootconfig data may not
be updated if you do incremental build the kernel with CONFIG_LTO. This is
under investigation.

[3] https://lore.kernel.org/all/20220321183500.GA4065@pswork/T/#u

Thank you,

---

Masami Hiramatsu (3):
      bootconfig: Check the checksum before removing the bootconfig from initrd
      bootconfig: Support embedding a bootconfig file in kernel
      docs: bootconfig: Add how to embed the bootconfig into kernel


 Documentation/admin-guide/bootconfig.rst |   30 ++++++++++++++++++++++++++---
 include/linux/bootconfig.h               |   10 ++++++++++
 init/Kconfig                             |   21 ++++++++++++++++++++
 init/main.c                              |   31 +++++++++++++++---------------
 lib/.gitignore                           |    1 +
 lib/Makefile                             |   10 ++++++++++
 lib/bootconfig.c                         |   23 ++++++++++++++++++++++
 7 files changed, 108 insertions(+), 18 deletions(-)

--
Masami Hiramatsu (Linaro) <mhiramat@kernel.org>

[PATCH v4 1/3] bootconfig: Check the checksum before removing the bootconfig from initrd

[Masami Hiramatsu]

Check the bootconfig's checksum before removing the bootcinfig data
from initrd to avoid modifying initrd by mistake.
This will also simplifies the get_boot_config_from_initrd() interface.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 init/main.c |   22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/init/main.c b/init/main.c
index 560f45c27ffe..4f3ba3b84e34 100644
--- a/init/main.c
+++ b/init/main.c
@@ -265,7 +265,7 @@ static int __init loglevel(char *str)
 early_param("loglevel", loglevel);
 
 #ifdef CONFIG_BLK_DEV_INITRD
-static void * __init get_boot_config_from_initrd(u32 *_size, u32 *_csum)
+static void * __init get_boot_config_from_initrd(u32 *_size)
 {
 	u32 size, csum;
 	char *data;
@@ -299,17 +299,20 @@ static void * __init get_boot_config_from_initrd(u32 *_size, u32 *_csum)
 		return NULL;
 	}
 
+	if (xbc_calc_checksum(data, size) != csum) {
+		pr_err("bootconfig checksum failed\n");
+		return NULL;
+	}
+
 	/* Remove bootconfig from initramfs/initrd */
 	initrd_end = (unsigned long)data;
 	if (_size)
 		*_size = size;
-	if (_csum)
-		*_csum = csum;
 
 	return data;
 }
 #else
-static void * __init get_boot_config_from_initrd(u32 *_size, u32 *_csum)
+static void * __init get_boot_config_from_initrd(u32 *_size)
 {
 	return NULL;
 }
@@ -408,12 +411,12 @@ static void __init setup_boot_config(void)
 	static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
 	const char *msg;
 	int pos;
-	u32 size, csum;
+	u32 size;
 	char *data, *err;
 	int ret;
 
 	/* Cut out the bootconfig data even if we have no bootconfig option */
-	data = get_boot_config_from_initrd(&size, &csum);
+	data = get_boot_config_from_initrd(&size);
 
 	strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 	err = parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL,
@@ -437,11 +440,6 @@ static void __init setup_boot_config(void)
 		return;
 	}
 
-	if (xbc_calc_checksum(data, size) != csum) {
-		pr_err("bootconfig checksum failed\n");
-		return;
-	}
-
 	ret = xbc_init(data, size, &msg, &pos);
 	if (ret < 0) {
 		if (pos < 0)
@@ -470,7 +468,7 @@ static void __init exit_boot_config(void)
 static void __init setup_boot_config(void)
 {
 	/* Remove bootconfig data from initrd */
-	get_boot_config_from_initrd(NULL, NULL);
+	get_boot_config_from_initrd(NULL);
 }
 
 static int __init warn_bootconfig(char *str)

[PATCH v4 2/3] bootconfig: Support embedding a bootconfig file in kernel

[Masami Hiramatsu]

This allows kernel developer to embed a default bootconfig file in
the kernel instead of embedding it in the initrd. This will be good
for who are using the kernel without initrd, or who needs a default
bootconfigs.
This needs to set two kconfigs: CONFIG_EMBED_BOOT_CONFIG=y and set
the file path to CONFIG_EMBED_BOOT_CONFIG_FILE.

Note that you still need 'bootconfig' command line option to load the
embedded bootconfig. Also if you boot using an initrd with a different
bootconfig, the kernel will use the bootconfig in the initrd, instead
of the default bootconfig.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 Changes in v3:
  - Avoid updating the default.bconf if the file is not changed.
---
 include/linux/bootconfig.h |   10 ++++++++++
 init/Kconfig               |   21 +++++++++++++++++++++
 init/main.c                |   13 ++++++++-----
 lib/.gitignore             |    1 +
 lib/Makefile               |   10 ++++++++++
 lib/bootconfig.c           |   23 +++++++++++++++++++++++
 6 files changed, 73 insertions(+), 5 deletions(-)

diff --git a/include/linux/bootconfig.h b/include/linux/bootconfig.h
index a4665c7ab07c..5dbda5e3e9bb 100644
--- a/include/linux/bootconfig.h
+++ b/include/linux/bootconfig.h
@@ -289,4 +289,14 @@ int __init xbc_get_info(int *node_size, size_t *data_size);
 /* XBC cleanup data structures */
 void __init xbc_exit(void);
 
+/* XBC embedded bootconfig data in kernel */
+#ifdef CONFIG_EMBED_BOOT_CONFIG
+char * __init xbc_get_embedded_bootconfig(size_t *size);
+#else
+static inline char *xbc_get_embedded_bootconfig(size_t *size)
+{
+	return NULL;
+}
+#endif
+
 #endif
diff --git a/init/Kconfig b/init/Kconfig
index beb5b866c318..bff308a782f8 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1357,6 +1357,27 @@ config BOOT_CONFIG
 
 	  If unsure, say Y.
 
+config EMBED_BOOT_CONFIG
+	bool "Embed bootconfig file in the kernel"
+	depends on BOOT_CONFIG
+	default n
+	help
+	  Embed a bootconfig file given by EMBED_BOOT_CONFIG_FILE in the
+	  kernel. Usually, the bootconfig file is loaded with the initrd
+	  image. But if the system doesn't support initrd, this option will
+	  help you by embedding a bootconfig file while building the kernel.
+
+	  If unsure, say N.
+
+config EMBED_BOOT_CONFIG_FILE
+	string "Embedded bootconfig file path"
+	default ""
+	depends on EMBED_BOOT_CONFIG
+	help
+	  Specify a bootconfig file which will be embedded to the kernel.
+	  This bootconfig will be used if there is no initrd or no other
+	  bootconfig in the initrd.
+
 choice
 	prompt "Compiler optimization level"
 	default CC_OPTIMIZE_FOR_PERFORMANCE
diff --git a/init/main.c b/init/main.c
index 4f3ba3b84e34..180511324c95 100644
--- a/init/main.c
+++ b/init/main.c
@@ -265,7 +265,7 @@ static int __init loglevel(char *str)
 early_param("loglevel", loglevel);
 
 #ifdef CONFIG_BLK_DEV_INITRD
-static void * __init get_boot_config_from_initrd(u32 *_size)
+static void * __init get_boot_config_from_initrd(size_t *_size)
 {
 	u32 size, csum;
 	char *data;
@@ -411,12 +411,15 @@ static void __init setup_boot_config(void)
 	static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
 	const char *msg;
 	int pos;
-	u32 size;
+	size_t size;
 	char *data, *err;
 	int ret;
 
 	/* Cut out the bootconfig data even if we have no bootconfig option */
 	data = get_boot_config_from_initrd(&size);
+	/* If there is no bootconfig in initrd, try embedded one. */
+	if (!data)
+		data = xbc_get_embedded_bootconfig(&size);
 
 	strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 	err = parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL,
@@ -435,8 +438,8 @@ static void __init setup_boot_config(void)
 	}
 
 	if (size >= XBC_DATA_MAX) {
-		pr_err("bootconfig size %d greater than max size %d\n",
-			size, XBC_DATA_MAX);
+		pr_err("bootconfig size %ld greater than max size %d\n",
+			(long)size, XBC_DATA_MAX);
 		return;
 	}
 
@@ -449,7 +452,7 @@ static void __init setup_boot_config(void)
 				msg, pos);
 	} else {
 		xbc_get_info(&ret, NULL);
-		pr_info("Load bootconfig: %d bytes %d nodes\n", size, ret);
+		pr_info("Load bootconfig: %ld bytes %d nodes\n", (long)size, ret);
 		/* keys starting with "kernel." are passed via cmdline */
 		extra_command_line = xbc_make_cmdline("kernel");
 		/* Also, "init." keys are init arguments */
diff --git a/lib/.gitignore b/lib/.gitignore
index e5e217b8307b..30a2a5db7033 100644
--- a/lib/.gitignore
+++ b/lib/.gitignore
@@ -6,3 +6,4 @@
 /oid_registry_data.c
 /test_fortify.log
 /test_fortify/*.log
+/default.bconf
diff --git a/lib/Makefile b/lib/Makefile
index 353bc09ce38d..dd9f3ebb62ca 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -276,6 +276,16 @@ $(foreach file, $(libfdt_files), \
 	$(eval CFLAGS_$(file) = -I $(srctree)/scripts/dtc/libfdt))
 lib-$(CONFIG_LIBFDT) += $(libfdt_files)
 
+ifeq ($(CONFIG_EMBED_BOOT_CONFIG),y)
+$(obj)/bootconfig.o: $(obj)/default.bconf
+
+targets += default.bconf
+filechk_defbconf = cat /dev/null $(CONFIG_EMBED_BOOT_CONFIG_FILE)
+$(obj)/default.bconf: FORCE
+	$(call filechk,defbconf)
+
+endif
+
 lib-$(CONFIG_BOOT_CONFIG) += bootconfig.o
 
 obj-$(CONFIG_RBTREE_TEST) += rbtree_test.o
diff --git a/lib/bootconfig.c b/lib/bootconfig.c
index 74f3201ab8e5..3a3bf3a208e3 100644
--- a/lib/bootconfig.c
+++ b/lib/bootconfig.c
@@ -12,6 +12,29 @@
 #include <linux/kernel.h>
 #include <linux/memblock.h>
 #include <linux/string.h>
+
+#ifdef CONFIG_EMBED_BOOT_CONFIG
+asm (
+"	.pushsection .init.data, \"aw\"			\n"
+"	.global embedded_bootconfig_data		\n"
+"embedded_bootconfig_data:				\n"
+"	.incbin \"lib/default.bconf\"			\n"
+"	.global embedded_bootconfig_data_end		\n"
+"embedded_bootconfig_data_end:				\n"
+"	.popsection					\n"
+);
+
+extern __visible char embedded_bootconfig_data[];
+extern __visible char embedded_bootconfig_data_end[];
+
+char * __init xbc_get_embedded_bootconfig(size_t *size)
+{
+	*size = embedded_bootconfig_data_end - embedded_bootconfig_data;
+	return (*size) ? embedded_bootconfig_data : NULL;
+}
+
+#endif
+
 #else /* !__KERNEL__ */
 /*
  * NOTE: This is only for tools/bootconfig, because tools/bootconfig will

[PATCH v4 3/3] docs: bootconfig: Add how to embed the bootconfig into kernel

[Masami Hiramatsu]

Add a description how to embed the bootconfig file into kernel.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 Changes in v3:
  - Fix typos.
 Changes in v2:
  - Corrected the text accoding to Randy's suggestion.
  - Do not reccomend to use relative path for CONFIG_EMBED_BOOT_CONFIG_FILE.
---
 Documentation/admin-guide/bootconfig.rst |   30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/bootconfig.rst b/Documentation/admin-guide/bootconfig.rst
index a1860fc0ca88..9028e0f1307b 100644
--- a/Documentation/admin-guide/bootconfig.rst
+++ b/Documentation/admin-guide/bootconfig.rst
@@ -158,9 +158,15 @@ Each key-value pair is shown in each line with following style::
 Boot Kernel With a Boot Config
 ==============================
 
-Since the boot configuration file is loaded with initrd, it will be added
-to the end of the initrd (initramfs) image file with padding, size,
-checksum and 12-byte magic word as below.
+There are two options to boot the kernel with bootconfig: attaching the
+bootconfig to the initrd image or embedding it in the kernel itself.
+
+Attaching a Boot Config to Initrd
+---------------------------------
+
+Since the boot configuration file is loaded with initrd by default,
+it will be added to the end of the initrd (initramfs) image file with
+padding, size, checksum and 12-byte magic word as below.
 
 [initrd][bootconfig][padding][size(le32)][checksum(le32)][#BOOTCONFIG\n]
 
@@ -196,6 +202,24 @@ To remove the config from the image, you can use -d option as below::
 Then add "bootconfig" on the normal kernel command line to tell the
 kernel to look for the bootconfig at the end of the initrd file.
 
+Embedding a Boot Config into Kernel
+-----------------------------------
+
+If you can not use initrd, you can also embed the bootconfig file in the
+kernel by Kconfig options. In this case, you need to recompile the kernel
+with the following configs::
+
+ CONFIG_EMBED_BOOT_CONFIG=y
+ CONFIG_EMBED_BOOT_CONFIG_FILE="/PATH/TO/BOOTCONFIG/FILE"
+
+``CONFIG_EMBED_BOOT_CONFIG_FILE`` requires a correct absolute path to
+the bootconfig file. The kernel will embed it as the default bootconfig.
+
+Just as when attaching the bootconfig to the initrd, you need ``bootconfig``
+option on the kernel command line to enable the embedded bootconfig.
+
+Note that even if you set this option, you can override the embedded
+bootconfig by another bootconfig which attached to the initrd.
 
 Kernel parameters via Boot Config
 =================================

Re: [PATCH v4 0/3] bootconfig: Support embedding a bootconfig in kernel for non initrd boot

[Masami Hiramatsu]

Hi Padmanabha,

On Sun, 27 Mar 2022 08:53:06 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:
> 
> 
> KNOWN ISSUE:
> 
> According to the report from Padmanabha[3], the embedded bootconfig data may not
> be updated if you do incremental build the kernel with CONFIG_LTO. This is
> under investigation.

I tried to test this version with LTO_CLANG_FULL and LTO_CLANG_THIN with
switching the embedded bootconfig file by CONFIG_EMBED_BOOT_CONFIG_FILE (on x86).

I found that when I use LTO_CLANG_FULL, the embedded bootconfig was updated
correctly.
But with the LTO_CLANG_THIN, the embedded bootconfig was *NOT* updated.

I used the latest prebuild llvm 15.0.0 on x86 [4]. Padmanabha, can you confirm
with this latest LLVM? I guess something wrong with your old LLVM.

[4] https://download.01.org/0day-ci/cross-package/clang-latest/clang-latest/clang.tar.xz

Here is the test procedure.

1. Prepare 2 different bootconfig files (bconf1, bconf2).
2. Configure kernel with LTO_CLANG and setting the full path of bconf1 to
   CONFIG_EMBED_BOOT_CONFIG_FILE.
3. Build the kernel
4. Boot the kernel with "bootconfig" in the kernel cmdline.
5. Check the /proc/bootconfig is same as bconf1.
6. Reconfigure kernel with the full path of *bconf2* to CONFIG_EMBED_BOOT_CONFIG_FILE.
7. Rebuild the kernel (no cleanup)
8. Boot the kernel with "bootconfig" in the kernel cmdline.
9. Check the /proc/bootconfig is same as bconf2.

So with LTO_CLANG_FULL, at the step 9 /proc/bootconfig shows bconf2, but with
LTO_CLANG_THIN, it shows bconf1.

In both cases, build log showed that the default.bconf was updated (I confirmed the
lib/default.bconf is updated)

  UPD     lib/default.bconf
  CC      lib/bootconfig.o
  AR      lib/lib.a


Here is my guess. I found that when we enable LTO_CLANG, the compiler compiles
C source file into LLVM IR bitcode.

$ file work/linux/build-x86_64/lib/bootconfig.o 
work/linux/build-x86_64/lib/bootconfig.o: LLVM IR bitcode

This means at this point the object file doesn't include the lib/default.bconf
because it will be embedded by assembler. The bitcode seems only have the
inline asm code (which only has an .incbin directive) as a constatns block[5].

[5]
  Block ID #11 (CONSTANTS_BLOCK):
      Num Instances: 32
         Total Size: 54305b/6788.12B/1697W
    Percent of file: 19.9792%
       Average Size: 1697.03/212.13B/53W
  Tot/Avg SubBlocks: 0/0.000000e+00
    Tot/Avg Abbrevs: 4/1.250000e-01
    Tot/Avg Records: 486/1.518750e+01
    Percent Abbrevs: 80.8642%

        Record Histogram:
                  Count    # Bits     b/Rec   % Abv  Record Kind
                    219      4860      22.2  100.00  INTEGER
                    144      1728      12.0  100.00  SETTYPE
                     41       656      16.0          NULL
                     39      2970      76.2          CE_INBOUNDS_GEP
                     26      3504     134.8  100.00  CSTRING
                     10     37720    3772.0          INLINEASM
                      4        96      24.0  100.00  CE_CAST
                      1        58                    CE_CMP
                      1        52                    CE_SELECT
                      1        46                    CE_BINOP

And when the LLVM runs LTO with THIN mode, it might not update (not rebuild to
machine code) that inline asm code block because that block is not updated.
I confirmed that the block (bootconfig.o) is not updated after rebuilding
the kernel as below.

After step 3.
$ llvm-bcanalyzer work/linux/build-x86_64/lib/bootconfig.o > bconf.dump1
After step 7.
$ llvm-bcanalyzer work/linux/build-x86_64/lib/bootconfig.o > bconf.dump2
$ diff bconf.dump*
(No difference)

Thank you,

> 
> [3] https://lore.kernel.org/all/20220321183500.GA4065@pswork/T/#u
> 
> Thank you,
> 
> ---
> 
> Masami Hiramatsu (3):
>       bootconfig: Check the checksum before removing the bootconfig from initrd
>       bootconfig: Support embedding a bootconfig file in kernel
>       docs: bootconfig: Add how to embed the bootconfig into kernel
> 
> 
>  Documentation/admin-guide/bootconfig.rst |   30 ++++++++++++++++++++++++++---
>  include/linux/bootconfig.h               |   10 ++++++++++
>  init/Kconfig                             |   21 ++++++++++++++++++++
>  init/main.c                              |   31 +++++++++++++++---------------
>  lib/.gitignore                           |    1 +
>  lib/Makefile                             |   10 ++++++++++
>  lib/bootconfig.c                         |   23 ++++++++++++++++++++++
>  7 files changed, 108 insertions(+), 18 deletions(-)
> 
> --
> Masami Hiramatsu (Linaro) <mhiramat@kernel.org>


-- 
Masami Hiramatsu <mhiramat@kernel.org>

Re: [PATCH v4 2/3] bootconfig: Support embedding a bootconfig file in kernel

[Masahiro Yamada]

On Sun, Mar 27, 2022 at 8:53 AM Masami Hiramatsu <mhiramat@kernel.org> wrote:
>
> This allows kernel developer to embed a default bootconfig file in
> the kernel instead of embedding it in the initrd. This will be good
> for who are using the kernel without initrd, or who needs a default
> bootconfigs.
> This needs to set two kconfigs: CONFIG_EMBED_BOOT_CONFIG=y and set
> the file path to CONFIG_EMBED_BOOT_CONFIG_FILE.
>
> Note that you still need 'bootconfig' command line option to load the
> embedded bootconfig. Also if you boot using an initrd with a different
> bootconfig, the kernel will use the bootconfig in the initrd, instead
> of the default bootconfig.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
>  Changes in v3:
>   - Avoid updating the default.bconf if the file is not changed.
> ---
>  include/linux/bootconfig.h |   10 ++++++++++
>  init/Kconfig               |   21 +++++++++++++++++++++
>  init/main.c                |   13 ++++++++-----
>  lib/.gitignore             |    1 +
>  lib/Makefile               |   10 ++++++++++
>  lib/bootconfig.c           |   23 +++++++++++++++++++++++
>  6 files changed, 73 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/bootconfig.h b/include/linux/bootconfig.h
> index a4665c7ab07c..5dbda5e3e9bb 100644
> --- a/include/linux/bootconfig.h
> +++ b/include/linux/bootconfig.h
> @@ -289,4 +289,14 @@ int __init xbc_get_info(int *node_size, size_t *data_size);
>  /* XBC cleanup data structures */
>  void __init xbc_exit(void);
>
> +/* XBC embedded bootconfig data in kernel */
> +#ifdef CONFIG_EMBED_BOOT_CONFIG
> +char * __init xbc_get_embedded_bootconfig(size_t *size);
> +#else
> +static inline char *xbc_get_embedded_bootconfig(size_t *size)
> +{
> +       return NULL;
> +}
> +#endif
> +
>  #endif
> diff --git a/init/Kconfig b/init/Kconfig
> index beb5b866c318..bff308a782f8 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1357,6 +1357,27 @@ config BOOT_CONFIG
>
>           If unsure, say Y.
>
> +config EMBED_BOOT_CONFIG
> +       bool "Embed bootconfig file in the kernel"
> +       depends on BOOT_CONFIG
> +       default n
> +       help
> +         Embed a bootconfig file given by EMBED_BOOT_CONFIG_FILE in the
> +         kernel. Usually, the bootconfig file is loaded with the initrd
> +         image. But if the system doesn't support initrd, this option will
> +         help you by embedding a bootconfig file while building the kernel.
> +
> +         If unsure, say N.
> +
> +config EMBED_BOOT_CONFIG_FILE
> +       string "Embedded bootconfig file path"
> +       default ""
> +       depends on EMBED_BOOT_CONFIG
> +       help
> +         Specify a bootconfig file which will be embedded to the kernel.
> +         This bootconfig will be used if there is no initrd or no other
> +         bootconfig in the initrd.
> +
>  choice
>         prompt "Compiler optimization level"
>         default CC_OPTIMIZE_FOR_PERFORMANCE
> diff --git a/init/main.c b/init/main.c
> index 4f3ba3b84e34..180511324c95 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -265,7 +265,7 @@ static int __init loglevel(char *str)
>  early_param("loglevel", loglevel);
>
>  #ifdef CONFIG_BLK_DEV_INITRD
> -static void * __init get_boot_config_from_initrd(u32 *_size)
> +static void * __init get_boot_config_from_initrd(size_t *_size)
>  {
>         u32 size, csum;
>         char *data;
> @@ -411,12 +411,15 @@ static void __init setup_boot_config(void)
>         static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
>         const char *msg;
>         int pos;
> -       u32 size;
> +       size_t size;
>         char *data, *err;
>         int ret;
>
>         /* Cut out the bootconfig data even if we have no bootconfig option */
>         data = get_boot_config_from_initrd(&size);
> +       /* If there is no bootconfig in initrd, try embedded one. */
> +       if (!data)
> +               data = xbc_get_embedded_bootconfig(&size);
>
>         strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
>         err = parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL,
> @@ -435,8 +438,8 @@ static void __init setup_boot_config(void)
>         }
>
>         if (size >= XBC_DATA_MAX) {
> -               pr_err("bootconfig size %d greater than max size %d\n",
> -                       size, XBC_DATA_MAX);
> +               pr_err("bootconfig size %ld greater than max size %d\n",
> +                       (long)size, XBC_DATA_MAX);
>                 return;
>         }
>
> @@ -449,7 +452,7 @@ static void __init setup_boot_config(void)
>                                 msg, pos);
>         } else {
>                 xbc_get_info(&ret, NULL);
> -               pr_info("Load bootconfig: %d bytes %d nodes\n", size, ret);
> +               pr_info("Load bootconfig: %ld bytes %d nodes\n", (long)size, ret);
>                 /* keys starting with "kernel." are passed via cmdline */
>                 extra_command_line = xbc_make_cmdline("kernel");
>                 /* Also, "init." keys are init arguments */
> diff --git a/lib/.gitignore b/lib/.gitignore
> index e5e217b8307b..30a2a5db7033 100644
> --- a/lib/.gitignore
> +++ b/lib/.gitignore
> @@ -6,3 +6,4 @@
>  /oid_registry_data.c
>  /test_fortify.log
>  /test_fortify/*.log
> +/default.bconf


I think lib/.gitignore is alphabetically sorted.

Please insert the new one
to the proper line.





> diff --git a/lib/Makefile b/lib/Makefile
> index 353bc09ce38d..dd9f3ebb62ca 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -276,6 +276,16 @@ $(foreach file, $(libfdt_files), \
>         $(eval CFLAGS_$(file) = -I $(srctree)/scripts/dtc/libfdt))
>  lib-$(CONFIG_LIBFDT) += $(libfdt_files)
>
> +ifeq ($(CONFIG_EMBED_BOOT_CONFIG),y)
> +$(obj)/bootconfig.o: $(obj)/default.bconf
> +
> +targets += default.bconf


I did not test this patch, but presumably
"make clean" will miss to clean up default.bconf

The 'targets' must exist outside the ifeq-block.
Move the 'endif' up.


ifeq ($(CONFIG_EMBED_BOOT_CONFIG),y)
$(obj)/bootconfig.o: $(obj)/default.bconf
endif

targets += default.bconf

...





> +filechk_defbconf = cat /dev/null $(CONFIG_EMBED_BOOT_CONFIG_FILE)
> +$(obj)/default.bconf: FORCE
> +       $(call filechk,defbconf)


This will work, but users will be confused when they
try to build out-of-tree with the O= option.

If CONFIG_EMBED_BOOT_CONFIG_FILE is a relative path,
it is actually relative to the object tree, not the source tree.
I am not sure if that is the expected behavior, but it is not documented
anywhere.


If you want to search both in the objtree and srctree,
you can write like follows:   [UNTESTED]


filechk_defbconf = cat $(or $(real-prereqs), /dev/null)
$(obj)/default.bconf: $(CONFIG_EMBED_BOOT_CONFIG_FILE) FORCE
        $(call filechk,defbconf)




> +
> +endif
> +
>  lib-$(CONFIG_BOOT_CONFIG) += bootconfig.o
>
>  obj-$(CONFIG_RBTREE_TEST) += rbtree_test.o
> diff --git a/lib/bootconfig.c b/lib/bootconfig.c
> index 74f3201ab8e5..3a3bf3a208e3 100644
> --- a/lib/bootconfig.c
> +++ b/lib/bootconfig.c
> @@ -12,6 +12,29 @@
>  #include <linux/kernel.h>
>  #include <linux/memblock.h>
>  #include <linux/string.h>
> +
> +#ifdef CONFIG_EMBED_BOOT_CONFIG
> +asm (
> +"      .pushsection .init.data, \"aw\"                 \n"
> +"      .global embedded_bootconfig_data                \n"
> +"embedded_bootconfig_data:                             \n"
> +"      .incbin \"lib/default.bconf\"                   \n"
> +"      .global embedded_bootconfig_data_end            \n"
> +"embedded_bootconfig_data_end:                         \n"
> +"      .popsection                                     \n"
> +);
> +
> +extern __visible char embedded_bootconfig_data[];
> +extern __visible char embedded_bootconfig_data_end[];
> +
> +char * __init xbc_get_embedded_bootconfig(size_t *size)
> +{
> +       *size = embedded_bootconfig_data_end - embedded_bootconfig_data;
> +       return (*size) ? embedded_bootconfig_data : NULL;
> +}
> +
> +#endif
> +
>  #else /* !__KERNEL__ */
>  /*
>   * NOTE: This is only for tools/bootconfig, because tools/bootconfig will
>


-- 
Best Regards
Masahiro Yamada

Re: [PATCH v4 2/3] bootconfig: Support embedding a bootconfig file in kernel

[Masami Hiramatsu]

On Mon, 28 Mar 2022 15:27:43 +0900
Masahiro Yamada <masahiroy@kernel.org> wrote:

> On Sun, Mar 27, 2022 at 8:53 AM Masami Hiramatsu <mhiramat@kernel.org> wrote:
> >
> > This allows kernel developer to embed a default bootconfig file in
> > the kernel instead of embedding it in the initrd. This will be good
> > for who are using the kernel without initrd, or who needs a default
> > bootconfigs.
> > This needs to set two kconfigs: CONFIG_EMBED_BOOT_CONFIG=y and set
> > the file path to CONFIG_EMBED_BOOT_CONFIG_FILE.
> >
> > Note that you still need 'bootconfig' command line option to load the
> > embedded bootconfig. Also if you boot using an initrd with a different
> > bootconfig, the kernel will use the bootconfig in the initrd, instead
> > of the default bootconfig.
> >
> > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> > ---
> >  Changes in v3:
> >   - Avoid updating the default.bconf if the file is not changed.
> > ---
> >  include/linux/bootconfig.h |   10 ++++++++++
> >  init/Kconfig               |   21 +++++++++++++++++++++
> >  init/main.c                |   13 ++++++++-----
> >  lib/.gitignore             |    1 +
> >  lib/Makefile               |   10 ++++++++++
> >  lib/bootconfig.c           |   23 +++++++++++++++++++++++
> >  6 files changed, 73 insertions(+), 5 deletions(-)
> >
> > diff --git a/include/linux/bootconfig.h b/include/linux/bootconfig.h
> > index a4665c7ab07c..5dbda5e3e9bb 100644
> > --- a/include/linux/bootconfig.h
> > +++ b/include/linux/bootconfig.h
> > @@ -289,4 +289,14 @@ int __init xbc_get_info(int *node_size, size_t *data_size);
> >  /* XBC cleanup data structures */
> >  void __init xbc_exit(void);
> >
> > +/* XBC embedded bootconfig data in kernel */
> > +#ifdef CONFIG_EMBED_BOOT_CONFIG
> > +char * __init xbc_get_embedded_bootconfig(size_t *size);
> > +#else
> > +static inline char *xbc_get_embedded_bootconfig(size_t *size)
> > +{
> > +       return NULL;
> > +}
> > +#endif
> > +
> >  #endif
> > diff --git a/init/Kconfig b/init/Kconfig
> > index beb5b866c318..bff308a782f8 100644
> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -1357,6 +1357,27 @@ config BOOT_CONFIG
> >
> >           If unsure, say Y.
> >
> > +config EMBED_BOOT_CONFIG
> > +       bool "Embed bootconfig file in the kernel"
> > +       depends on BOOT_CONFIG
> > +       default n
> > +       help
> > +         Embed a bootconfig file given by EMBED_BOOT_CONFIG_FILE in the
> > +         kernel. Usually, the bootconfig file is loaded with the initrd
> > +         image. But if the system doesn't support initrd, this option will
> > +         help you by embedding a bootconfig file while building the kernel.
> > +
> > +         If unsure, say N.
> > +
> > +config EMBED_BOOT_CONFIG_FILE
> > +       string "Embedded bootconfig file path"
> > +       default ""
> > +       depends on EMBED_BOOT_CONFIG
> > +       help
> > +         Specify a bootconfig file which will be embedded to the kernel.
> > +         This bootconfig will be used if there is no initrd or no other
> > +         bootconfig in the initrd.
> > +
> >  choice
> >         prompt "Compiler optimization level"
> >         default CC_OPTIMIZE_FOR_PERFORMANCE
> > diff --git a/init/main.c b/init/main.c
> > index 4f3ba3b84e34..180511324c95 100644
> > --- a/init/main.c
> > +++ b/init/main.c
> > @@ -265,7 +265,7 @@ static int __init loglevel(char *str)
> >  early_param("loglevel", loglevel);
> >
> >  #ifdef CONFIG_BLK_DEV_INITRD
> > -static void * __init get_boot_config_from_initrd(u32 *_size)
> > +static void * __init get_boot_config_from_initrd(size_t *_size)
> >  {
> >         u32 size, csum;
> >         char *data;
> > @@ -411,12 +411,15 @@ static void __init setup_boot_config(void)
> >         static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
> >         const char *msg;
> >         int pos;
> > -       u32 size;
> > +       size_t size;
> >         char *data, *err;
> >         int ret;
> >
> >         /* Cut out the bootconfig data even if we have no bootconfig option */
> >         data = get_boot_config_from_initrd(&size);
> > +       /* If there is no bootconfig in initrd, try embedded one. */
> > +       if (!data)
> > +               data = xbc_get_embedded_bootconfig(&size);
> >
> >         strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
> >         err = parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL,
> > @@ -435,8 +438,8 @@ static void __init setup_boot_config(void)
> >         }
> >
> >         if (size >= XBC_DATA_MAX) {
> > -               pr_err("bootconfig size %d greater than max size %d\n",
> > -                       size, XBC_DATA_MAX);
> > +               pr_err("bootconfig size %ld greater than max size %d\n",
> > +                       (long)size, XBC_DATA_MAX);
> >                 return;
> >         }
> >
> > @@ -449,7 +452,7 @@ static void __init setup_boot_config(void)
> >                                 msg, pos);
> >         } else {
> >                 xbc_get_info(&ret, NULL);
> > -               pr_info("Load bootconfig: %d bytes %d nodes\n", size, ret);
> > +               pr_info("Load bootconfig: %ld bytes %d nodes\n", (long)size, ret);
> >                 /* keys starting with "kernel." are passed via cmdline */
> >                 extra_command_line = xbc_make_cmdline("kernel");
> >                 /* Also, "init." keys are init arguments */
> > diff --git a/lib/.gitignore b/lib/.gitignore
> > index e5e217b8307b..30a2a5db7033 100644
> > --- a/lib/.gitignore
> > +++ b/lib/.gitignore
> > @@ -6,3 +6,4 @@
> >  /oid_registry_data.c
> >  /test_fortify.log
> >  /test_fortify/*.log
> > +/default.bconf
> 
> 
> I think lib/.gitignore is alphabetically sorted.
> 
> Please insert the new one
> to the proper line.

Ah, OK. Let me fix that.

> > diff --git a/lib/Makefile b/lib/Makefile
> > index 353bc09ce38d..dd9f3ebb62ca 100644
> > --- a/lib/Makefile
> > +++ b/lib/Makefile
> > @@ -276,6 +276,16 @@ $(foreach file, $(libfdt_files), \
> >         $(eval CFLAGS_$(file) = -I $(srctree)/scripts/dtc/libfdt))
> >  lib-$(CONFIG_LIBFDT) += $(libfdt_files)
> >
> > +ifeq ($(CONFIG_EMBED_BOOT_CONFIG),y)
> > +$(obj)/bootconfig.o: $(obj)/default.bconf
> > +
> > +targets += default.bconf
> 
> 
> I did not test this patch, but presumably
> "make clean" will miss to clean up default.bconf
> 
> The 'targets' must exist outside the ifeq-block.
> Move the 'endif' up.
> 
> 
> ifeq ($(CONFIG_EMBED_BOOT_CONFIG),y)
> $(obj)/bootconfig.o: $(obj)/default.bconf
> endif
> 
> targets += default.bconf
> 
> ...

You're right! I didn't know this behavior. Thanks for the notice.
I misunderstood that the files in targets always be built...

After moving the 'targets' out of ifeq-block, I confirmed that the
default.bconf was not generated when CONFIG_EMBED_BOOT_CONFIG is not
set, and it is cleaned up when CONFIG_EMBED_BOOT_CONFIG=y.
Thanks!

> 
> > +filechk_defbconf = cat /dev/null $(CONFIG_EMBED_BOOT_CONFIG_FILE)
> > +$(obj)/default.bconf: FORCE
> > +       $(call filechk,defbconf)
> 
> 
> This will work, but users will be confused when they
> try to build out-of-tree with the O= option.
> 
> If CONFIG_EMBED_BOOT_CONFIG_FILE is a relative path,
> it is actually relative to the object tree, not the source tree.

Yes, that's right. I would like to fix this issue.

> I am not sure if that is the expected behavior, but it is not documented
> anywhere.
> 
> 
> If you want to search both in the objtree and srctree,
> you can write like follows:   [UNTESTED]
> 
> 
> filechk_defbconf = cat $(or $(real-prereqs), /dev/null)
> $(obj)/default.bconf: $(CONFIG_EMBED_BOOT_CONFIG_FILE) FORCE
>         $(call filechk,defbconf)

Great! let me check it works.

Thank you,

> 
> 
> 
> 
> > +
> > +endif
> > +
> >  lib-$(CONFIG_BOOT_CONFIG) += bootconfig.o
> >
> >  obj-$(CONFIG_RBTREE_TEST) += rbtree_test.o
> > diff --git a/lib/bootconfig.c b/lib/bootconfig.c
> > index 74f3201ab8e5..3a3bf3a208e3 100644
> > --- a/lib/bootconfig.c
> > +++ b/lib/bootconfig.c
> > @@ -12,6 +12,29 @@
> >  #include <linux/kernel.h>
> >  #include <linux/memblock.h>
> >  #include <linux/string.h>
> > +
> > +#ifdef CONFIG_EMBED_BOOT_CONFIG
> > +asm (
> > +"      .pushsection .init.data, \"aw\"                 \n"
> > +"      .global embedded_bootconfig_data                \n"
> > +"embedded_bootconfig_data:                             \n"
> > +"      .incbin \"lib/default.bconf\"                   \n"
> > +"      .global embedded_bootconfig_data_end            \n"
> > +"embedded_bootconfig_data_end:                         \n"
> > +"      .popsection                                     \n"
> > +);
> > +
> > +extern __visible char embedded_bootconfig_data[];
> > +extern __visible char embedded_bootconfig_data_end[];
> > +
> > +char * __init xbc_get_embedded_bootconfig(size_t *size)
> > +{
> > +       *size = embedded_bootconfig_data_end - embedded_bootconfig_data;
> > +       return (*size) ? embedded_bootconfig_data : NULL;
> > +}
> > +
> > +#endif
> > +
> >  #else /* !__KERNEL__ */
> >  /*
> >   * NOTE: This is only for tools/bootconfig, because tools/bootconfig will
> >
> 
> 
> -- 
> Best Regards
> Masahiro Yamada


-- 
Masami Hiramatsu <mhiramat@kernel.org>

Re: [PATCH v4 0/3] bootconfig: Support embedding a bootconfig in kernel for non initrd boot

[Padmanabha Srinivasaiah]

Hello Masami Hiramatsu,

Sorry for long delay, was out of town.

>On Sun, Mar 27, 2022 at 11:55:26AM +0900, Masami Hiramatsu wrote:
> Hi Padmanabha,
> 
> On Sun, 27 Mar 2022 08:53:06 +0900
> Masami Hiramatsu <mhiramat@kernel.org> wrote:
> > 
> > 
> > KNOWN ISSUE:
> > 
> > According to the report from Padmanabha[3], the embedded bootconfig data may not
> > be updated if you do incremental build the kernel with CONFIG_LTO. This is
> > under investigation.
> 
> I tried to test this version with LTO_CLANG_FULL and LTO_CLANG_THIN with
> switching the embedded bootconfig file by CONFIG_EMBED_BOOT_CONFIG_FILE (on x86).
> 
> I found that when I use LTO_CLANG_FULL, the embedded bootconfig was updated
> correctly.
> But with the LTO_CLANG_THIN, the embedded bootconfig was *NOT* updated.
> 
> I used the latest prebuild llvm 15.0.0 on x86 [4]. Padmanabha, can you confirm
> with this latest LLVM? I guess something wrong with your old LLVM.
> 
> [4] https://download.01.org/0day-ci/cross-package/clang-latest/clang-latest/clang.tar.xz
>

Thanks for the link for prebuilt llvm 15.0.0.

[p1] https://www.spinics.net/lists/kernel/msg4307362.html

With llvm 15.0.0 and latest patchset v8 for bootconfig [p1] on arm64 the
test observations are:

For bootconfig:

I dont observe anymore an issue with incremental builds, irresepctive of LTO
type selected: FULL/THIN.

For config.gz:

The test observations is exactly similar to yours.
With LTO_CLANG_THIN configs were *NOT* updated.
But with LTO_CLANG_FULL confs were updated.

Test results validates and confirms your earlier analysis on issue with
inline asm and .incbin directive and THIN_LTO. 

> Here is the test procedure.
> 
> 1. Prepare 2 different bootconfig files (bconf1, bconf2).
> 2. Configure kernel with LTO_CLANG and setting the full path of bconf1 to
>    CONFIG_EMBED_BOOT_CONFIG_FILE.
> 3. Build the kernel
> 4. Boot the kernel with "bootconfig" in the kernel cmdline.
> 5. Check the /proc/bootconfig is same as bconf1.
> 6. Reconfigure kernel with the full path of *bconf2* to CONFIG_EMBED_BOOT_CONFIG_FILE.
> 7. Rebuild the kernel (no cleanup)
> 8. Boot the kernel with "bootconfig" in the kernel cmdline.
> 9. Check the /proc/bootconfig is same as bconf2.
> 
> So with LTO_CLANG_FULL, at the step 9 /proc/bootconfig shows bconf2, but with
> LTO_CLANG_THIN, it shows bconf1.
> 
> In both cases, build log showed that the default.bconf was updated (I confirmed the
> lib/default.bconf is updated)
> 
>   UPD     lib/default.bconf
>   CC      lib/bootconfig.o
>   AR      lib/lib.a
> 
> 
> Here is my guess. I found that when we enable LTO_CLANG, the compiler compiles
> C source file into LLVM IR bitcode.
> 
> $ file work/linux/build-x86_64/lib/bootconfig.o 
> work/linux/build-x86_64/lib/bootconfig.o: LLVM IR bitcode
> 
> This means at this point the object file doesn't include the lib/default.bconf
> because it will be embedded by assembler. The bitcode seems only have the
> inline asm code (which only has an .incbin directive) as a constatns block[5].
>
> [5]
>   Block ID #11 (CONSTANTS_BLOCK):
>       Num Instances: 32
>          Total Size: 54305b/6788.12B/1697W
>     Percent of file: 19.9792%
>        Average Size: 1697.03/212.13B/53W
>   Tot/Avg SubBlocks: 0/0.000000e+00
>     Tot/Avg Abbrevs: 4/1.250000e-01
>     Tot/Avg Records: 486/1.518750e+01
>     Percent Abbrevs: 80.8642%
> 
>         Record Histogram:
>                   Count    # Bits     b/Rec   % Abv  Record Kind
>                     219      4860      22.2  100.00  INTEGER
>                     144      1728      12.0  100.00  SETTYPE
>                      41       656      16.0          NULL
>                      39      2970      76.2          CE_INBOUNDS_GEP
>                      26      3504     134.8  100.00  CSTRING
>                      10     37720    3772.0          INLINEASM
>                       4        96      24.0  100.00  CE_CAST
>                       1        58                    CE_CMP
>                       1        52                    CE_SELECT
>                       1        46                    CE_BINOP
> 
> And when the LLVM runs LTO with THIN mode, it might not update (not rebuild to
> machine code) that inline asm code block because that block is not updated.
> I confirmed that the block (bootconfig.o) is not updated after rebuilding
> the kernel as below.
>
Yes, thanks for details. Analysis is in sync with observations from test
results.

Thanks and Regards,
Padmanabha.S
> After step 3.
> $ llvm-bcanalyzer work/linux/build-x86_64/lib/bootconfig.o > bconf.dump1
> After step 7.
> $ llvm-bcanalyzer work/linux/build-x86_64/lib/bootconfig.o > bconf.dump2
> $ diff bconf.dump*
> (No difference)
> 
> Thank you,
> 
> > 
> > [3] https://lore.kernel.org/all/20220321183500.GA4065@pswork/T/#u
> > 
> > Thank you,
> > 
> > ---
> > 
> > Masami Hiramatsu (3):
> >       bootconfig: Check the checksum before removing the bootconfig from initrd
> >       bootconfig: Support embedding a bootconfig file in kernel
> >       docs: bootconfig: Add how to embed the bootconfig into kernel
> > 
> > 
> >  Documentation/admin-guide/bootconfig.rst |   30 ++++++++++++++++++++++++++---
> >  include/linux/bootconfig.h               |   10 ++++++++++
> >  init/Kconfig                             |   21 ++++++++++++++++++++
> >  init/main.c                              |   31 +++++++++++++++---------------
> >  lib/.gitignore                           |    1 +
> >  lib/Makefile                             |   10 ++++++++++
> >  lib/bootconfig.c                         |   23 ++++++++++++++++++++++
> >  7 files changed, 108 insertions(+), 18 deletions(-)
> > 
> > --
> > Masami Hiramatsu (Linaro) <mhiramat@kernel.org>
> 
> 
> -- 
> Masami Hiramatsu <mhiramat@kernel.org>

Re: [PATCH v4 0/3] bootconfig: Support embedding a bootconfig in kernel for non initrd boot

[Masami Hiramatsu]

Hi,

I forgot to add LTO people and Masahiro to this mail. Let me update the
cover mail and resubmit.

On Sun, 27 Mar 2022 08:36:53 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:

> Hi,
> 
> Here are the 4th version of the patchset to enable kernel embedded bootconfig
> for non-initrd kernel boot environment. I've fixed Makefile to determine
> update by checking the contents of embedding bootconfig file. Thanks
> Masahiro!
> 
> You can embed a bootconfig file into the kernel as a default bootconfig,
> which will be used if there is no initrd or no bootconfig is attached to initrd. 
> 
> This needs 2 options: CONFIG_EMBED_BOOT_CONFIG=y and set the file
> path to CONFIG_EMBED_BOOT_CONFIG_FILE. Even if you embed the bootconfig file
> to the kernel, it will not be enabled unless you pass "bootconfig" kernel
> command line option at boot. Moreover, since this is just a "default"
> bootconfig, you can override it with a new bootconfig if you attach another
> bootconfig to the initrd (if possible).
> CONFIG_EMBED_BOOT_CONFIG_FILE can take both absolute and relative path, but
> to simplify and make it independent from the build environment, I recommend
> you to use an absolute path for that.
> 
> This is requested by Padmanabha at the below thread;
> 
>  https://lore.kernel.org/all/20220307184011.GA2570@pswork/T/#u
> 
> Thank you,
> 
> ---
> 
> Masami Hiramatsu (3):
>       bootconfig: Check the checksum before removing the bootconfig from initrd
>       bootconfig: Support embedding a bootconfig file in kernel
>       docs: bootconfig: Add how to embed the bootconfig into kernel
> 
> 
>  Documentation/admin-guide/bootconfig.rst |   30 ++++++++++++++++++++++++++---
>  include/linux/bootconfig.h               |   10 ++++++++++
>  init/Kconfig                             |   21 ++++++++++++++++++++
>  init/main.c                              |   31 +++++++++++++++---------------
>  lib/.gitignore                           |    1 +
>  lib/Makefile                             |   10 ++++++++++
>  lib/bootconfig.c                         |   23 ++++++++++++++++++++++
>  7 files changed, 108 insertions(+), 18 deletions(-)
> 
> --
> Masami Hiramatsu (Linaro) <mhiramat@kernel.org>


-- 
Masami Hiramatsu <mhiramat@kernel.org>

[PATCH v4 0/3] bootconfig: Support embedding a bootconfig in kernel for non initrd boot

[Masami Hiramatsu]

Hi,

Here are the 4th version of the patchset to enable kernel embedded bootconfig
for non-initrd kernel boot environment. I've fixed Makefile to determine
update by checking the contents of embedding bootconfig file. Thanks
Masahiro!

You can embed a bootconfig file into the kernel as a default bootconfig,
which will be used if there is no initrd or no bootconfig is attached to initrd. 

This needs 2 options: CONFIG_EMBED_BOOT_CONFIG=y and set the file
path to CONFIG_EMBED_BOOT_CONFIG_FILE. Even if you embed the bootconfig file
to the kernel, it will not be enabled unless you pass "bootconfig" kernel
command line option at boot. Moreover, since this is just a "default"
bootconfig, you can override it with a new bootconfig if you attach another
bootconfig to the initrd (if possible).
CONFIG_EMBED_BOOT_CONFIG_FILE can take both absolute and relative path, but
to simplify and make it independent from the build environment, I recommend
you to use an absolute path for that.

This is requested by Padmanabha at the below thread;

 https://lore.kernel.org/all/20220307184011.GA2570@pswork/T/#u

Thank you,

---

Masami Hiramatsu (3):
      bootconfig: Check the checksum before removing the bootconfig from initrd
      bootconfig: Support embedding a bootconfig file in kernel
      docs: bootconfig: Add how to embed the bootconfig into kernel


 Documentation/admin-guide/bootconfig.rst |   30 ++++++++++++++++++++++++++---
 include/linux/bootconfig.h               |   10 ++++++++++
 init/Kconfig                             |   21 ++++++++++++++++++++
 init/main.c                              |   31 +++++++++++++++---------------
 lib/.gitignore                           |    1 +
 lib/Makefile                             |   10 ++++++++++
 lib/bootconfig.c                         |   23 ++++++++++++++++++++++
 7 files changed, 108 insertions(+), 18 deletions(-)

--
Masami Hiramatsu (Linaro) <mhiramat@kernel.org>