[Xen-ia64-devel] [patch 09/16] Kexec/Kdump: honour non-zero crashkernel offset

[Simon Horman <horms@xxxxxxxxxxxx>]

There seems to be a value in both allowing the kernel to determine
the base offset of the crashkernel automatically and allowing
users's to sepcify it.

The old behaviour on ia64, which is still the current behaviour on
most architectures is for the user to always specify the address.
Recently ia64 was changed so that it is always automatically determined.

With this patch the kernel automatically determines the offset if
the supplied value is 0, otherwise it uses the value provided.

This should probably be backed by a documentation change.

Signed-Off-By: Simon Horman <horms@xxxxxxxxxxxx>
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>

---
>From Linux upstream, commit ad1c3ba7e54fc38b119c1a7d5c98f9ffb8227fdb

 arch/ia64/kernel/setup.c |   14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

Date: Wed, 19 Sep 2007 12:03:48 +0900
From: Horms <horms@xxxxxxxxxxxx>

Note that as his change is a backport of a change that has already been
committed to upstream Linux, its really just part of the backport
of ia64 kexec from Linux (~2.6.21) to linux-xen 2.6.18. For this
reason I think that it should remain part of this patch-set.

Index: linux-2.6.18-xen.hg/arch/ia64/kernel/setup.c
===================================================================
--- linux-2.6.18-xen.hg.orig/arch/ia64/kernel/setup.c   2007-07-09 
15:00:34.000000000 +0900
+++ linux-2.6.18-xen.hg/arch/ia64/kernel/setup.c        2007-07-09 
15:03:32.000000000 +0900
@@ -299,7 +299,7 @@ reserve_memory (void)
 
 #ifdef CONFIG_KEXEC
        /* crashkernel=size@offset specifies the size to reserve for a crash
-        * kernel.(offset is ingored for keep compatibility with other archs)
+        * kernel. If offset is 0, then it is determined automatically.
         * By reserving this memory we guarantee that linux never set's it
         * up as a DMA target.Useful for holding code to do something
         * appropriate after a kernel panic.
@@ -310,10 +310,16 @@ reserve_memory (void)
 #ifndef CONFIG_XEN
                if (from) {
                        size = memparse(from + 12, &from);
+                       if (*from == '@')
+                               base = memparse(from+1, &from);
+                       else
+                               base = 0;
                        if (size) {
-                               sort_regions(rsvd_region, n);
-                               base = kdump_find_rsvd_region(size,
-                               rsvd_region, n);
+                               if (!base) {
+                                       sort_regions(rsvd_region, n);
+                                       base = kdump_find_rsvd_region(size,
+                                                               rsvd_region, n);
+                                       }
                                if (base != ~0UL) {
                                        rsvd_region[n].start =
                                                (unsigned long)__va(base);

-- 

-- 
Horms
  H: http://www.vergenet.net/~horms/
  W: http://www.valinux.co.jp/en/


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