MIPS: Add support for extending builtin cmdline

Allow the builtin command line to be extended by what the bootloader
passes in.  For example, the bootloader can pass specific arguments
depending on the boot mode, and these should override the defaults in
the builtin cmdline.

The default MIPS_CMDLINE_FROM_BOOTLOADER option prepends the
bootloader's cmdline to the builtin cmdline so is not suitable for this
purpose.

Signed-off-by: Rabin Vincent <rabinv@axis.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13181/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 5cc5b62..d10ed57 100644 (file)
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2930,6 +2930,10 @@ choice
 
        config MIPS_CMDLINE_FROM_BOOTLOADER
                bool "Bootloader kernel arguments if available"
+
+       config MIPS_CMDLINE_BUILTIN_EXTEND
+               depends on CMDLINE_BOOL
+               bool "Extend builtin kernel arguments with bootloader arguments"
 endchoice
 
 endmenu

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 38815f7..19c03a9 100644 (file)
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -640,6 +640,8 @@ static void __init request_crashkernel(struct resource *res)
 #define USE_PROM_CMDLINE       IS_ENABLED(CONFIG_MIPS_CMDLINE_FROM_BOOTLOADER)
 #define USE_DTB_CMDLINE                IS_ENABLED(CONFIG_MIPS_CMDLINE_FROM_DTB)
 #define EXTEND_WITH_PROM       IS_ENABLED(CONFIG_MIPS_CMDLINE_DTB_EXTEND)
+#define BUILTIN_EXTEND_WITH_PROM       \
+       IS_ENABLED(CONFIG_MIPS_CMDLINE_BUILTIN_EXTEND)
 
 static void __init arch_mem_init(char **cmdline_p)
 {
@@ -684,6 +686,12 @@ static void __init arch_mem_init(char **cmdline_p)
                        strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
                strlcat(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
        }
+
+       if (BUILTIN_EXTEND_WITH_PROM && arcs_cmdline[0]) {
+               if (boot_command_line[0])
+                       strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
+               strlcat(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
+       }
 #endif
 #endif
        strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);