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Commit 6acc7d48 authored by Dmitri Vorobiev's avatar Dmitri Vorobiev Committed by Ralf Baechle
Browse files

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: default avatarDmitri Vorobiev <dmitri.vorobiev@movial.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/689/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent de4148f3

arch/mips/Kconfig.debug

+41 −4
Original line number Diff line number Diff line
@@ -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"

arch/mips/configs/ar7_defconfig

+2 −0
Original line number Diff line number Diff line
@@ -1051,7 +1051,9 @@ CONFIG_TRACING_SUPPORT=y 
# CONFIG_DYNAMIC_DEBUG is not set

# CONFIG_SAMPLES is not set

CONFIG_HAVE_ARCH_KGDB=y

CONFIG_CMDLINE_BOOL=y

CONFIG_CMDLINE="rootfstype=squashfs,jffs2"

# CONFIG_CMDLINE_OVERRIDE is not set



#

# Security options

arch/mips/configs/bcm47xx_defconfig

+1 −1
Original line number Diff line number Diff line
@@ -1852,7 +1852,7 @@ CONFIG_DEBUG_FS=y 
# CONFIG_HEADERS_CHECK is not set

# CONFIG_DEBUG_KERNEL is not set

# CONFIG_SAMPLES is not set

CONFIG_CMDLINE=""

# CONFIG_CMDLINE_BOOL is not set



#

# Security options

arch/mips/configs/bcm63xx_defconfig

+2 −0
Original line number Diff line number Diff line
@@ -941,7 +941,9 @@ CONFIG_TRACING_SUPPORT=y 
# CONFIG_BLK_DEV_IO_TRACE is not set

# CONFIG_SAMPLES is not set

CONFIG_HAVE_ARCH_KGDB=y

CONFIG_CMDLINE_BOOL=y

CONFIG_CMDLINE="console=ttyS0,115200"

# CONFIG_CMDLINE_OVERRIDE is not set



#

# Security options

arch/mips/configs/bigsur_defconfig

+1 −1
Original line number Diff line number Diff line
@@ -1236,7 +1236,7 @@ CONFIG_DEBUG_MUTEXES=y 
# CONFIG_BACKTRACE_SELF_TEST is not set

# CONFIG_FAULT_INJECTION is not set

# CONFIG_SAMPLES is not set

CONFIG_CMDLINE=""

# CONFIG_CMDLINE_BOOL is not set

# CONFIG_DEBUG_STACK_USAGE is not set

# CONFIG_SB1XXX_CORELIS is not set

# CONFIG_RUNTIME_DEBUG is not set