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authorYinghai Lu <yinghai@kernel.org>2013-01-24 12:20:11 -0800
committerH. Peter Anvin <hpa@linux.intel.com>2013-01-29 19:32:58 -0800
commit0212f9159694be61c6bc52e925fa76643e0c1abf (patch)
tree21fff008e27df08d3ab650d9c2421b490fcdc926 /Documentation/kernel-parameters.txt
parent7d41a8a4a2b2438621a9159477bff36a11d79a42 (diff)
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x86: Add Crash kernel low reservation
During kdump kernel's booting stage, it need to find low ram for swiotlb buffer when system does not support intel iommu/dmar remapping. kexed-tools is appending memmap=exactmap and range from /proc/iomem with "Crash kernel", and that range is above 4G for 64bit after boot protocol 2.12. We need to add another range in /proc/iomem like "Crash kernel low", so kexec-tools could find that info and append to kdump kernel command line. Try to reserve some under 4G if the normal "Crash kernel" is above 4G. User could specify the size with crashkernel_low=XX[KMG]. -v2: fix warning that is found by Fengguang's test robot. -v3: move out get_mem_size change to another patch, to solve compiling warning that is found by Borislav Petkov <bp@alien8.de> -v4: user must specify crashkernel_low if system does not support intel or amd iommu. Signed-off-by: Yinghai Lu <yinghai@kernel.org> Link: http://lkml.kernel.org/r/1359058816-7615-31-git-send-email-yinghai@kernel.org Cc: Eric Biederman <ebiederm@xmission.com> Cc: Rob Landley <rob@landley.net> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'Documentation/kernel-parameters.txt')
-rw-r--r--Documentation/kernel-parameters.txt3
1 files changed, 3 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 363e348..da0e077 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -594,6 +594,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
is selected automatically. Check
Documentation/kdump/kdump.txt for further details.
+ crashkernel_low=size[KMG]
+ [KNL, x86] parts under 4G.
+
crashkernel=range1:size1[,range2:size2,...][@offset]
[KNL] Same as above, but depends on the memory
in the running system. The syntax of range is
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