* [PATCH] arm64: Implement CONFIG_CMDLINE_EXTEND
@ 2015-11-18 9:28 Pavel Fedin
2015-11-18 16:09 ` Rob Herring
0 siblings, 1 reply; 2+ messages in thread
From: Pavel Fedin @ 2015-11-18 9:28 UTC (permalink / raw)
To: linux-arm-kernel
Add an option to extend built-in command line with one obtained from
the device tree.
This option is very useful for, for example, switching between some
stable and development version, when one of them requires additional
arguments (e. g. to turn on some extra debug). It can be annoying to
reprogram command line in the bootloaded every time.
Actually, this patch introduces the necessary support to all
architectures using the device tree, however only arm64 Kconfig is
modified, because this is the only platform i can test.
Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
---
arch/arm64/Kconfig | 18 ++++++++++++++++++
drivers/of/fdt.c | 12 ++++++++++--
2 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 9ac16a4..c741837 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -695,6 +695,23 @@ config CMDLINE
entering them here. As a minimum, you should specify the the
root device (e.g. root=/dev/nfs).
+choice
+ prompt "Kernel command line type" if CMDLINE != ""
+ default CMDLINE_FROM_BOOTLOADER
+
+config CMDLINE_FROM_BOOTLOADER
+ bool "Use bootloader kernel arguments if available"
+ help
+ Uses the command-line options passed by the boot loader. If
+ the boot loader doesn't provide any, the default kernel command
+ string provided in CMDLINE will be used.
+
+config CMDLINE_EXTEND
+ bool "Extend bootloader kernel arguments"
+ help
+ The command-line arguments provided by the boot loader will be
+ appended to the default kernel command string.
+
config CMDLINE_FORCE
bool "Always use the default kernel command string"
help
@@ -702,6 +719,7 @@ config CMDLINE_FORCE
loader passes other arguments to the kernel.
This is useful if you cannot or don't want to change the
command-line options your boot loader passes to the kernel.
+endchoice
config EFI_STUB
bool
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index d243029..494307e 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -949,8 +949,16 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
/* Retrieve command line */
p = of_get_flat_dt_prop(node, "bootargs", &l);
- if (p != NULL && l > 0)
- strlcpy(data, p, min((int)l, COMMAND_LINE_SIZE));
+ if (p != NULL && l > 0) {
+ int offset = 0;
+#ifdef CONFIG_CMDLINE
+#ifdef CONFIG_CMDLINE_EXTEND
+ strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
+ offset = strlcat(data, " ", COMMAND_LINE_SIZE);
+#endif
+#endif
+ strlcpy(data + offset, p, min(l, COMMAND_LINE_SIZE - offset));
+ }
/*
* CONFIG_CMDLINE is meant to be a default in case nothing else
--
2.4.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH] arm64: Implement CONFIG_CMDLINE_EXTEND
2015-11-18 9:28 [PATCH] arm64: Implement CONFIG_CMDLINE_EXTEND Pavel Fedin
@ 2015-11-18 16:09 ` Rob Herring
0 siblings, 0 replies; 2+ messages in thread
From: Rob Herring @ 2015-11-18 16:09 UTC (permalink / raw)
To: linux-arm-kernel
On Wed, Nov 18, 2015 at 3:28 AM, Pavel Fedin <p.fedin@samsung.com> wrote:
> Add an option to extend built-in command line with one obtained from
> the device tree.
>
> This option is very useful for, for example, switching between some
> stable and development version, when one of them requires additional
> arguments (e. g. to turn on some extra debug). It can be annoying to
> reprogram command line in the bootloaded every time.
>
> Actually, this patch introduces the necessary support to all
> architectures using the device tree, however only arm64 Kconfig is
> modified, because this is the only platform i can test.
There is work to make the cmdline options and handling generic[1].
There are lots of sharp corners here and I'd like to sort out the
generic support before adding more combinations.
Rob
[1] http://www.spinics.net/lists/arm-kernel/msg449844.html
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