[PATCH] kexec: change CONFIG_PHYSICAL_START dependency

I have heard some complaints about people not finding CONFIG_CRASH_DUMP
option and also some objections about its dependency on CONFIG_EMBEDDED.
The following patch ends that dependency.  I thought of hiding it under
CONFIG_KEXEC, but CONFIG_PHYSICAL_START could also be used for some reasons
other than kexec/kdump and hence left it visible.  I will also update the
documentation accordingly.

o Following patch removes the config dependency of CONFIG_PHYSICAL_START
  on CONFIG_EMBEDDED. The reason being CONFIG_CRASH_DUMP option for
  kdump needs CONFIG_PHYSICAL_START which makes CONFIG_CRASH_DUMP depend
  on CONFIG_EMBEDDED. It is not always obvious for kdump users to choose
  CONFIG_EMBEDDED.

o It also shifts the palce where this option appears, to make it closer
  to kexec and kdump options.

Signed-off-by: Maneesh Soni <maneesh@in.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Haren Myneni <haren@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 40 insertions, 24 deletions

diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index d849c6870e3a..554ce3f344c9 100644
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -645,17 +645,6 @@ config SECCOMP
 
 source kernel/Kconfig.hz
 
-config PHYSICAL_START
-        hex "Physical address where the kernel is loaded" if EMBEDDED
-        default "0x100000"
-        help
-          This gives the physical address where the kernel is loaded.
-          Primarily used in the case of kexec on panic where the
-          fail safe kernel needs to run at a different address than
-          the panic-ed kernel.
-
-          Don't change this unless you know what you are doing.
-
 config KEXEC
         bool "kexec system call (EXPERIMENTAL)"
         depends on EXPERIMENTAL
@@ -675,11 +664,31 @@ config KEXEC
 
 config CRASH_DUMP
         bool "kernel crash dumps (EXPERIMENTAL)"
-        depends on EMBEDDED
         depends on EXPERIMENTAL
         depends on HIGHMEM
         help
           Generate crash dump after being started by kexec.
+
+config PHYSICAL_START
+        hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
+
+        default "0x1000000" if CRASH_DUMP
+        default "0x100000"
+        help
+          This gives the physical address where the kernel is loaded. Normally
+          for regular kernels this value is 0x100000 (1MB). But in the case
+          of kexec on panic the fail safe kernel needs to run at a different
+          address than the panic-ed kernel. This option is used to set the load
+          address for kernels used to capture crash dump on being kexec'ed
+          after panic. The default value for crash dump kernels is
+          0x1000000 (16MB). This can also be set based on the "X" value as
+          specified in the "crashkernel=YM@XM" command line boot parameter
+          passed to the panic-ed kernel. Typically this parameter is set as
+          crashkernel=64M@16M. Please take a look at
+          Documentation/kdump/kdump.txt for more details about crash dumps.
+
+          Don't change this unless you know what you are doing.
+
 endmenu
 
 
diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index dd2d116b9ab8..348b4a0d0d6f 100644
--- a/arch/x86_64/Kconfig
+++ b/arch/x86_64/Kconfig
@@ -399,17 +399,6 @@ config X86_MCE_AMD
            Additional support for AMD specific MCE features such as
            the DRAM Error Threshold.
 
-config PHYSICAL_START
-        hex "Physical address where the kernel is loaded" if EMBEDDED
-        default "0x100000"
-        help
-          This gives the physical address where the kernel is loaded.
-          Primarily used in the case of kexec on panic where the
-          fail safe kernel needs to run at a different address than
-          the panic-ed kernel.
-
-          Don't change this unless you know what you are doing.
-
 config KEXEC
         bool "kexec system call (EXPERIMENTAL)"
         depends on EXPERIMENTAL
@@ -429,11 +418,29 @@ config KEXEC
 
 config CRASH_DUMP
         bool "kernel crash dumps (EXPERIMENTAL)"
-        depends on EMBEDDED
         depends on EXPERIMENTAL
         help
                 Generate crash dump after being started by kexec.
 
+config PHYSICAL_START
+        hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
+        default "0x1000000" if CRASH_DUMP
+        default "0x100000"
+        help
+          This gives the physical address where the kernel is loaded. Normally
+          for regular kernels this value is 0x100000 (1MB). But in the case
+          of kexec on panic the fail safe kernel needs to run at a different
+          address than the panic-ed kernel. This option is used to set the load
+          address for kernels used to capture crash dump on being kexec'ed
+          after panic. The default value for crash dump kernels is
+          0x1000000 (16MB). This can also be set based on the "X" value as
+          specified in the "crashkernel=YM@XM" command line boot parameter
+          passed to the panic-ed kernel. Typically this parameter is set as
+          crashkernel=64M@16M. Please take a look at
+          Documentation/kdump/kdump.txt for more details about crash dumps.
+
+          Don't change this unless you know what you are doing.
+
 config SECCOMP
         bool "Enable seccomp to safely compute untrusted bytecode"
         depends on PROC_FS