[PATCH v2 6/7] cmdline: Gives architectures opportunity to use generically defined boot cmdline manipulation

[Christophe Leroy]

Most architectures have similar boot command line manipulation
options. This patchs adds the definition in init/Kconfig, gated by
CONFIG_HAVE_CMDLINE that the architectures can select to use them.

In order to use this, a few architectures will have to change their
CONFIG options:
- riscv has to replace CMDLINE_FALLBACK by CMDLINE_FROM_BOOTLOADER
- architectures using CONFIG_CMDLINE_OVERRIDE or
CONFIG_CMDLINE_OVERWRITE have to replace them by CONFIG_CMDLINE_FORCE.

Architectures also have to define CONFIG_DEFAULT_CMDLINE.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
 init/Kconfig | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/init/Kconfig b/init/Kconfig
index 22946fe5ded9..a0f2ad9467df 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -117,6 +117,62 @@ config INIT_ENV_ARG_LIMIT
 	  Maximum of each of the number of arguments and environment
 	  variables passed to init from the kernel command line.
 
+config HAVE_CMDLINE
+	bool
+
+config CMDLINE_BOOL
+	bool "Default bootloader kernel arguments"
+	depends on HAVE_CMDLINE
+	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
+	  most cases you will need to specify the root device here.
+
+config CMDLINE
+	string "Initial kernel command string"
+	depends on CMDLINE_BOOL
+	default DEFAULT_CMDLINE
+	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
+	  most cases you will need to specify the root device here.
+
+choice
+	prompt "Kernel command line type" if CMDLINE != ""
+	default CMDLINE_FROM_BOOTLOADER
+	help
+	  Selects the way you want to use the default kernel arguments.
+
+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 default kernel command string will be appended to the
+	  command-line arguments provided during boot.
+
+config CMDLINE_PREPEND
+	bool "Prepend bootloader kernel arguments"
+	help
+	  The default kernel command string will be prepend to the
+	  command-line arguments provided during boot.
+
+config CMDLINE_FORCE
+	bool "Always use the default kernel command string"
+	help
+	  Always use the default kernel command string, even if the boot
+	  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 COMPILE_TEST
 	bool "Compile also drivers which will not load"
 	depends on !UML && !S390
-- 
2.25.0