target/linux/generic/pending-4.9/920-mangle_bootargs.patch

   1 From: Imre Kaloz <kaloz@openwrt.org>
   2 Subject: init: add CONFIG_MANGLE_BOOTARGS and disable it by default
   3
   4 Enabling this option renames the bootloader supplied root=
   5 and rootfstype= variables, which might have to be know but
   6 would break the automatisms OpenWrt uses.
   7
   8 Signed-off-by: Imre Kaloz <kaloz@openwrt.org>
   9 ---
  10  init/Kconfig |  9 +++++++++
  11  init/main.c  | 24 ++++++++++++++++++++++++
  12  2 files changed, 33 insertions(+)
  13
  14 diff --git a/init/Kconfig b/init/Kconfig
  15 index 9063c81b9665..fb66d3ef78e0 100644
  16 --- a/init/Kconfig
  17 +++ b/init/Kconfig
  18 @@ -1687,6 +1687,15 @@ config EMBEDDED
  19           an embedded system so certain expert options are available
  20           for configuration.
  21
  22 +config MANGLE_BOOTARGS
  23 +       bool "Rename offending bootargs"
  24 +       depends on EXPERT
  25 +       help
  26 +         Sometimes the bootloader passed bogus root= and rootfstype=
  27 +         parameters to the kernel, and while you want to ignore them,
  28 +         you need to know the values f.e. to support dual firmware
  29 +         layouts on the flash.
  30 +
  31  config HAVE_PERF_EVENTS
  32         bool
  33         help
  34 diff --git a/init/main.c b/init/main.c
  35 index ae3996ae9bac..3855fa4ffb95 100644
  36 --- a/init/main.c
  37 +++ b/init/main.c
  38 @@ -352,6 +352,29 @@ static inline void setup_nr_cpu_ids(void) { }
  39  static inline void smp_prepare_cpus(unsigned int maxcpus) { }
  40  #endif
  41
  42 +#ifdef CONFIG_MANGLE_BOOTARGS
  43 +static void __init mangle_bootargs(char *command_line)
  44 +{
  45 +       char *rootdev;
  46 +       char *rootfs;
  47 +
  48 +       rootdev = strstr(command_line, "root=/dev/mtdblock");
  49 +
  50 +       if (rootdev)
  51 +               strncpy(rootdev, "mangled_rootblock=", 18);
  52 +
  53 +       rootfs = strstr(command_line, "rootfstype");
  54 +
  55 +       if (rootfs)
  56 +               strncpy(rootfs, "mangled_fs", 10);
  57 +
  58 +}
  59 +#else
  60 +static void __init mangle_bootargs(char *command_line)
  61 +{
  62 +}
  63 +#endif
  64 +
  65  /*
  66   * We need to store the untouched command line for future reference.
  67   * We also need to store the touched command line since the parameter
  68 @@ -504,6 +527,7 @@ asmlinkage __visible void __init start_kernel(void)
  69         pr_notice("%s", linux_banner);
  70         setup_arch(&command_line);
  71         mm_init_cpumask(&init_mm);
  72 +       mangle_bootargs(command_line);
  73         setup_command_line(command_line);
  74         setup_nr_cpu_ids();
  75         setup_per_cpu_areas();
  76 --
  77 2.11.0
  78