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MIPS: Fix and enhance built-in kernel command line

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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>
This commit is contained in:
Dmitri Vorobiev
2009-11-21 22:34:41 +02:00
committed by Ralf Baechle
parent de4148f3ef
commit 6acc7d485c
48 changed files with 123 additions and 38 deletions
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45
arch/mips/Kconfig.debug
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@ -20,15 +20,52 @@ config EARLY_PRINTK
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"