2008-08-25 13:00:59

by Gregory Haskins

[permalink] [raw]
Subject: [PATCH] Subject: x86: Move crashkernel reservation before dma32_reserve_bootmem()

Hi Steven, Ingo, Thomas,
Bernard (cc'd) sent me this patch for 26.3-rt3 to fix an issue where a kdump
kernel will fail to load, thereby disabling the crashdump feature. Please
consider this patch for -rt4. IIUC, this patch is already upstream in the
.27 series.

-Greg

-----------------
From: Bernhard Walle <[email protected]>

On a x86-64 machine (nothing special I could encounter) I had the problem that
crashkernel reservation with the usual "64M@16M" failed. While debugging that,
I encountered that dma32_reserve_bootmem() reserves a memory region which is in
that area.

Because dma32_reserve_bootmem() does not rely on a specific offset but
crashkernel does, it makes sense to move the crashkernel reservation up a bit.
I tested that patch and it works without problems. I don't see any negative
effects of that move, but maybe I oversaw something ...

While the long-term solution is to make the crashkernel reservation dynamic
(which is already done in -tip), this bug should be fixed also short-term for
2.6.26 (or 2.6.26-stable if it's too short), and that's why I made that patch.


Signed-off-by: Bernhard Walle <[email protected]>
Signed-off-by: Gregory Haskins <[email protected]>
---

arch/x86/kernel/setup_64.c | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/setup_64.c b/arch/x86/kernel/setup_64.c
index 6dff128..158cefe 100644
--- a/arch/x86/kernel/setup_64.c
+++ b/arch/x86/kernel/setup_64.c
@@ -444,6 +444,12 @@ void __init setup_arch(char **cmdline_p)
contig_initmem_init(0, end_pfn);
#endif

+ /*
+ * dma32_reserve_bootmem() allocates bootmem which may conflict
+ * with the crashkernel command line, so do that before
+ */
+ reserve_crashkernel();
+
dma32_reserve_bootmem();

#ifdef CONFIG_ACPI_SLEEP
@@ -484,7 +490,6 @@ void __init setup_arch(char **cmdline_p)
}
}
#endif
- reserve_crashkernel();

reserve_ibft_region();


2008-08-26 08:38:53

by Bernhard Walle

[permalink] [raw]
Subject: Re: [PATCH] Subject: x86: Move crashkernel reservation before dma32_reserve_bootmem()

* Gregory Haskins [2008-08-25 08:58]:
>
> Bernard (cc'd) sent me this patch for 26.3-rt3 to fix an issue where a kdump
> kernel will fail to load, thereby disabling the crashdump feature. Please
> consider this patch for -rt4. IIUC, this patch is already upstream in the
> .27 series.

commit 91467bdf6e53058af13fd255375d6634ba0c70e0
Author: Bernhard Walle <[email protected]>
Date: Fri Jul 18 19:07:53 2008 +0200



Bernhard
--
Bernhard Walle, SUSE LINUX Products GmbH, Architecture Development