OpenWrt – Rev 1

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From: Imre Kaloz <kaloz@openwrt.org>
Subject: init: add CONFIG_MANGLE_BOOTARGS and disable it by default

Enabling this option renames the bootloader supplied root=
and rootfstype= variables, which might have to be know but
would break the automatisms OpenWrt uses.

Signed-off-by: Imre Kaloz <kaloz@openwrt.org>
---
 init/Kconfig |  9 +++++++++
 init/main.c  | 24 ++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1427,6 +1427,15 @@ config EMBEDDED
          an embedded system so certain expert options are available
          for configuration.
 
+config MANGLE_BOOTARGS
+       bool "Rename offending bootargs"
+       depends on EXPERT
+       help
+         Sometimes the bootloader passed bogus root= and rootfstype=
+         parameters to the kernel, and while you want to ignore them,
+         you need to know the values f.e. to support dual firmware
+         layouts on the flash.
+
 config HAVE_PERF_EVENTS
        bool
        help
--- a/init/main.c
+++ b/init/main.c
@@ -359,6 +359,29 @@ static inline void setup_nr_cpu_ids(void
 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 #endif
 
+#ifdef CONFIG_MANGLE_BOOTARGS
+static void __init mangle_bootargs(char *command_line)
+{
+       char *rootdev;
+       char *rootfs;
+
+       rootdev = strstr(command_line, "root=/dev/mtdblock");
+
+       if (rootdev)
+               strncpy(rootdev, "mangled_rootblock=", 18);
+
+       rootfs = strstr(command_line, "rootfstype");
+
+       if (rootfs)
+               strncpy(rootfs, "mangled_fs", 10);
+
+}
+#else
+static void __init mangle_bootargs(char *command_line)
+{
+}
+#endif
+
 /*
  * We need to store the untouched command line for future reference.
  * We also need to store the touched command line since the parameter
@@ -540,6 +563,7 @@ asmlinkage __visible void __init start_k
        add_device_randomness(command_line, strlen(command_line));
        boot_init_stack_canary();
        mm_init_cpumask(&init_mm);
+       mangle_bootargs(command_line);
        setup_command_line(command_line);
        setup_nr_cpu_ids();
        setup_per_cpu_areas();