[PATCH] x86: Move dma32_reserve_bootmem() after reserve_crashkernel()

Bernhard Walle bwalle at suse.de
Fri Jul 18 13:07:53 EDT 2008

On a x86-64 machine (nothing special I could encounter) I had the problem that
crashkernel reservation with the usual "64M at 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 dma32_reserve_bootmem()
reservation down 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 we strictly don't need that patch in 2.6.27 because we have the
automatic, dynamic offset detection, it makes sense to also include it here

  - it's easier to get it in -stable then,
  - many people are still used to the 'crashkernel=... at 16M' syntax,
  - not everybody may be using a reloatable kernel.

Signed-off-by: Bernhard Walle <bwalle at suse.de>
 arch/x86/kernel/setup.c |   13 +++++++++----
 1 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 531b55b..74d110e 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -792,10 +792,6 @@ void __init setup_arch(char **cmdline_p)
 	initmem_init(0, max_pfn);
-#ifdef CONFIG_X86_64
-	dma32_reserve_bootmem();
 	 * Reserve low memory region for sleep support.
@@ -810,6 +806,15 @@ void __init setup_arch(char **cmdline_p)
+#ifdef CONFIG_X86_64
+	/*
+	 * dma32_reserve_bootmem() allocates bootmem which may conflict
+	 * with the crashkernel command line, so do that after
+	 * reserve_crashkernel()
+	 */
+	dma32_reserve_bootmem();

More information about the kexec mailing list