2 files changed, 61 insertions, 0 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ac2fb0641a04..fbcb79bbafd2 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1392,6 +1392,51 @@ config COMPAT_VDSO
 
           If unsure, say Y.
 
+config CMDLINE_BOOL
+        bool "Built-in kernel command line"
+        default n
+        help
+          Allow for specifying boot arguments to the kernel at
+          build time.  On some systems (e.g. embedded ones), it is
+          necessary or convenient to provide some or all of the
+          kernel boot arguments with the kernel itself (that is,
+          to not rely on the boot loader to provide them.)
+
+          To compile command line arguments into the kernel,
+          set this option to 'Y', then fill in the
+          the boot arguments in CONFIG_CMDLINE.
+
+          Systems with fully functional boot loaders (i.e. non-embedded)
+          should leave this option set to 'N'.
+
+config CMDLINE
+        string "Built-in kernel command string"
+        depends on CMDLINE_BOOL
+        default ""
+        help
+          Enter arguments here that should be compiled into the kernel
+          image and used at boot time.  If the boot loader provides a
+          command line at boot time, it is appended to this string to
+          form the full kernel command line, when the system boots.
+
+          However, you can use the CONFIG_CMDLINE_OVERRIDE option to
+          change this behavior.
+
+          In most cases, the command line (whether built-in or provided
+          by the boot loader) should specify the device for the root
+          file system.
+
+config CMDLINE_OVERRIDE
+        bool "Built-in command line overrides boot loader arguments"
+        default n
+        depends on CMDLINE_BOOL
+        help
+          Set this option to 'Y' to have the kernel ignore the boot loader
+          command line, and use ONLY the built-in command line.
+
+          This is used to work around broken boot loaders.  This should
+          be set to 'N' under normal conditions.
+
 endmenu
 
 config ARCH_ENABLE_MEMORY_HOTPLUG
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 68b48e3fbcbd..2f31cddd27b7 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -223,6 +223,9 @@ unsigned long saved_video_mode;
 #define RAMDISK_LOAD_FLAG               0x4000
 
 static char __initdata command_line[COMMAND_LINE_SIZE];
+#ifdef CONFIG_CMDLINE_BOOL
+static char __initdata builtin_cmdline[COMMAND_LINE_SIZE] = CONFIG_CMDLINE;
+#endif
 
 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
 struct edd edd;
@@ -673,6 +676,19 @@ void __init setup_arch(char **cmdline_p)
         bss_resource.start = virt_to_phys(&__bss_start);
         bss_resource.end = virt_to_phys(&__bss_stop)-1;
 
+#ifdef CONFIG_CMDLINE_BOOL
+#ifdef CONFIG_CMDLINE_OVERRIDE
+        strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
+#else
+        if (builtin_cmdline[0]) {
+                /* append boot loader cmdline to builtin */
+                strlcat(builtin_cmdline, " ", COMMAND_LINE_SIZE);
+                strlcat(builtin_cmdline, boot_command_line, COMMAND_LINE_SIZE);
+                strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
+        }
+#endif
+#endif
+
         strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
         *cmdline_p = command_line;