MIPS: Fix and enhance built-in kernel command line
Currently, MIPS kernels silently overwrite kernel command-line parameters
hardcoded in CONFIG_CMDLINE by the ones received from firmware. Therefore,
using firmware remains the only reliable method to transfer the
command-line parameters, which is not always desirable or convenient, and
the CONFIG_CMDLINE option is thereby effectively rendered useless.
This patch fixes the problem described above and introduces a more flexible
scheme of handling the kernel command line, in a manner identical to what is
currently used for x86. The default behavior, i.e. when CONFIG_CMDLINE_BOOL
is not defined, retains the existing semantics, and firmware command-line
arguments override the hardcoded ones.
[Ralf: I fixed up all the defconfig files so the stay unaffected by this
change.]
Signed-off-by: Dmitri Vorobiev <dmitri.vorobiev@movial.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/689/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kconfig.debug b/arch/mips/Kconfig.debug
index 23817bc..d2b88a0 100644
--- a/arch/mips/Kconfig.debug
+++ b/arch/mips/Kconfig.debug
@@ -20,15 +20,52 @@
doesn't cooperate with an X server. You should normally say N here,
unless you want to debug such a crash.
+config CMDLINE_BOOL
+ bool "Built-in kernel command line"
+ default n
+ help
+ For most systems, it is firmware or second stage bootloader that
+ by default specifies the kernel command line options. However,
+ it might be necessary or advantageous to either override the
+ default kernel command line or add a few extra options to it.
+ For such cases, this option allows you to hardcode your own
+ command line options directly into the kernel. For that, you
+ should choose 'Y' here, and fill in the extra boot arguments
+ in CONFIG_CMDLINE.
+
+ The built-in options will be concatenated to the default command
+ line if CMDLINE_OVERRIDE is set to 'N'. Otherwise, the default
+ command line will be ignored and replaced by the built-in string.
+
+ Most MIPS systems will normally expect 'N' here and rely upon
+ the command line from the firmware or the second-stage bootloader.
+
config CMDLINE
string "Default kernel command string"
+ depends on CMDLINE_BOOL
default ""
help
On some platforms, there is currently no way for the boot loader to
- pass arguments to the kernel. For these platforms, you can supply
- some command-line options at build time by entering them here. In
- other cases you can specify kernel args so that you don't have
- to set them up in board prom initialization routines.
+ pass arguments to the kernel. For these platforms, and for the cases
+ when you want to add some extra options to the command line or ignore
+ the default command line, you can supply some command-line options at
+ build time by entering them here. In other cases you can specify
+ kernel args so that you don't have to set them up in board prom
+ initialization routines.
+
+ For more information, see the CMDLINE_BOOL and CMDLINE_OVERRIDE
+ options.
+
+config CMDLINE_OVERRIDE
+ bool "Built-in command line overrides firware arguments"
+ default n
+ depends on CMDLINE_BOOL
+ help
+ By setting this option to 'Y' you will have your kernel ignore
+ command line arguments from firmware or second stage bootloader.
+ Instead, the built-in command line will be used exclusively.
+
+ Normally, you will choose 'N' here.
config DEBUG_STACK_USAGE
bool "Enable stack utilization instrumentation"