generic: 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>

SVN-Revision: 45196

target/linux/generic/config-3.18

@@ -1910,6 +1910,7 @@ CONFIG_LZMA_DECOMPRESS=y
 # CONFIG_MAGIC_SYSRQ is not set
 CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE=0x1
 # CONFIG_MAILBOX is not set
+# CONFIG_MANGLE_BOOTARGS is not set
 # CONFIG_MARVELL_PHY is not set
 # CONFIG_MAX1027 is not set
 # CONFIG_MAX1363 is not set

target/linux/generic/config-4.0

@@ -1945,6 +1945,7 @@ CONFIG_LZMA_DECOMPRESS=y
 # CONFIG_MAGIC_SYSRQ is not set
 CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE=0x1
 # CONFIG_MAILBOX is not set
+# CONFIG_MANGLE_BOOTARGS is not set
 # CONFIG_MARVELL_PHY is not set
 # CONFIG_MAX1027 is not set
 # CONFIG_MAX1363 is not set

target/linux/generic/patches-3.18/995-mangle_bootargs.patch

@@ -0,0 +1,55 @@
+--- a/init/main.c
++++ b/init/main.c
+@@ -379,6 +379,26 @@ static void __init setup_command_line(ch
+ 	strcpy(static_command_line, command_line);
+ }
+ 
++#ifdef CONFIG_MANGLE_BOOTARGS
++static void __init mangle_bootargs(char *command_line)
++{
++	char *rootdev;
++	char *rootfs;
++
++	rootdev = strstr(command_line, "root=/dev/mtdblock");
++	strncpy(rootdev, "mangled_rootblock=", 18);
++
++	rootfs = strstr(command_line, "rootfstype");
++	strncpy(rootfs, "mangled_fs", 10);
++
++}
++#else
++static void __init mangle_bootargs(char *command_line)
++{
++}
++#endif
++
++
+ /*
+  * We need to finalize in a non-__init function or else race conditions
+  * between the root thread and the init thread may cause start_kernel to
+@@ -530,6 +550,7 @@ asmlinkage __visible void __init start_k
+ 	pr_notice("%s", linux_banner);
+ 	setup_arch(&command_line);
+ 	mm_init_cpumask(&init_mm);
++	mangle_bootargs(command_line);
+ 	setup_command_line(command_line);
+ 	setup_nr_cpu_ids();
+ 	setup_per_cpu_areas();
+--- a/init/Kconfig
++++ b/init/Kconfig
+@@ -1597,6 +1597,15 @@ 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

target/linux/generic/patches-4.0/995-mangle_bootargs.patch

@@ -0,0 +1,55 @@
+--- a/init/main.c
++++ b/init/main.c
+@@ -368,6 +368,26 @@ static void __init setup_command_line(ch
+ 	strcpy(static_command_line, command_line);
+ }
+ 
++#ifdef CONFIG_MANGLE_BOOTARGS
++static void __init mangle_bootargs(char *command_line)
++{
++	char *rootdev;
++	char *rootfs;
++
++	rootdev = strstr(command_line, "root=/dev/mtdblock");
++	strncpy(rootdev, "mangled_rootblock=", 18);
++
++	rootfs = strstr(command_line, "rootfstype");
++	strncpy(rootfs, "mangled_fs", 10);
++
++}
++#else
++static void __init mangle_bootargs(char *command_line)
++{
++}
++#endif
++
++
+ /*
+  * We need to finalize in a non-__init function or else race conditions
+  * between the root thread and the init thread may cause start_kernel to
+@@ -519,6 +539,7 @@ asmlinkage __visible void __init start_k
+ 	pr_notice("%s", linux_banner);
+ 	setup_arch(&command_line);
+ 	mm_init_cpumask(&init_mm);
++	mangle_bootargs(command_line);
+ 	setup_command_line(command_line);
+ 	setup_nr_cpu_ids();
+ 	setup_per_cpu_areas();
+--- a/init/Kconfig
++++ b/init/Kconfig
+@@ -1583,6 +1583,15 @@ 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