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 <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>

1 files changed, 20 insertions, 4 deletions

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index bd55f71055ba..f9513f9e61d3 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -58,8 +58,12 @@ EXPORT_SYMBOL(mips_machtype);
 
 struct boot_mem_map boot_mem_map;
 
-static char command_line[COMMAND_LINE_SIZE];
-       char arcs_cmdline[COMMAND_LINE_SIZE] = CONFIG_CMDLINE;
+static char __initdata command_line[COMMAND_LINE_SIZE];
+char __initdata arcs_cmdline[COMMAND_LINE_SIZE];
+
+#ifdef CONFIG_CMDLINE_BOOL
+static char __initdata builtin_cmdline[COMMAND_LINE_SIZE] = CONFIG_CMDLINE;
+#endif
 
 /*
  * mips_io_port_base is the begin of the address space to which x86 style
@@ -458,8 +462,20 @@ static void __init arch_mem_init(char **cmdline_p)
         pr_info("Determined physical RAM map:\n");
         print_memory_map();
 
-        strlcpy(command_line, arcs_cmdline, sizeof(command_line));
-        strlcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
+#ifdef CONFIG_CMDLINE_BOOL
+#ifdef CONFIG_CMDLINE_OVERRIDE
+        strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
+#else
+        if (builtin_cmdline[0]) {
+                strlcat(arcs_cmdline, " ", COMMAND_LINE_SIZE);
+                strlcat(arcs_cmdline, builtin_cmdline, COMMAND_LINE_SIZE);
+        }
+        strlcpy(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
+#endif
+#else
+        strlcpy(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
+#endif
+        strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
 
         *cmdline_p = command_line;