From 6acc7d485c24c00e111c61b2e6dff9180faebcae Mon Sep 17 00:00:00 2001 From: Dmitri Vorobiev Date: Sat, 21 Nov 2009 22:34:41 +0200 Subject: 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 Cc: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/689/ Signed-off-by: Ralf Baechle --- arch/mips/Kconfig.debug | 45 +++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 41 insertions(+), 4 deletions(-) (limited to 'arch/mips/Kconfig.debug') diff --git a/arch/mips/Kconfig.debug b/arch/mips/Kconfig.debug index 23817bc7a26a..d2b88a0be519 100644 --- a/arch/mips/Kconfig.debug +++ b/arch/mips/Kconfig.debug @@ -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" -- cgit v1.2.3