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authorMohan Kumar M <mohan@in.ibm.com>2008-10-21 17:38:10 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2008-10-22 15:01:22 +1100
commit54622f10a6aabb8bb2bdacf3dd070046f03dc246 (patch)
tree73eb5ad4eeb7174b8c0ae1904bbe80602c5e295d /Documentation/kdump
parent4792adbac9eb41cea77a45ab76258ea10d411173 (diff)
downloadlinux-linaro-stable-54622f10a6aabb8bb2bdacf3dd070046f03dc246.tar.gz
powerpc: Support for relocatable kdump kernel
This adds relocatable kernel support for kdump. With this one can use the same regular kernel to capture the kdump. A signature (0xfeed1234) is passed in r6 from panic code to the next kernel through kexec_sequence and purgatory code. The signature is used to differentiate between kdump kernel and non-kdump kernels. The purgatory code compares the signature and sets the __kdump_flag in head_64.S. During the boot up, kernel code checks __kdump_flag and if it is set, the kernel will behave as relocatable kdump kernel. This kernel will boot at the address where it was loaded by kexec-tools ie. at the address reserved through crashkernel boot parameter. CONFIG_CRASH_DUMP depends on CONFIG_RELOCATABLE option to build kdump kernel as relocatable. So the same kernel can be used as production and kdump kernel. This patch incorporates the changes suggested by Paul Mackerras to avoid GOT use and to avoid two copies of the code. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Mohan Kumar M <mohan@in.ibm.com> Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'Documentation/kdump')
-rw-r--r--Documentation/kdump/kdump.txt14
1 files changed, 11 insertions, 3 deletions
diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index 0705040531a5..3f4bc840da8b 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -109,7 +109,8 @@ There are two possible methods of using Kdump.
2) Or use the system kernel binary itself as dump-capture kernel and there is
no need to build a separate dump-capture kernel. This is possible
only with the architecutres which support a relocatable kernel. As
- of today, i386, x86_64 and ia64 architectures support relocatable kernel.
+ of today, i386, x86_64, ppc64 and ia64 architectures support relocatable
+ kernel.
Building a relocatable kernel is advantageous from the point of view that
one does not have to build a second kernel for capturing the dump. But
@@ -207,8 +208,15 @@ Dump-capture kernel config options (Arch Dependent, i386 and x86_64)
Dump-capture kernel config options (Arch Dependent, ppc64)
----------------------------------------------------------
-* Make and install the kernel and its modules. DO NOT add this kernel
- to the boot loader configuration files.
+1) Enable "Build a kdump crash kernel" support under "Kernel" options:
+
+ CONFIG_CRASH_DUMP=y
+
+2) Enable "Build a relocatable kernel" support
+
+ CONFIG_RELOCATABLE=y
+
+ Make and install the kernel and its modules.
Dump-capture kernel config options (Arch Dependent, ia64)
----------------------------------------------------------