On 12/16/2015 02:17 AM, Will Deacon wrote:
On Tue, Nov 24, 2015 at 10:25:34PM +0000, Geoff Levand wrote:
From: AKASHI Takahiro <[email protected]>
This patch adds arch specific descriptions about kdump usage on arm64
to kdump.txt.
Signed-off-by: AKASHI Takahiro <[email protected]>
---
Documentation/kdump/kdump.txt | 32 +++++++++++++++++++++++++++++++-
1 file changed, 31 insertions(+), 1 deletion(-)
diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index bc4bd5a..7d3fad0 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -18,7 +18,7 @@ memory image to a dump file on the local disk, or across the
network to
a remote system.
Kdump and kexec are currently supported on the x86, x86_64, ppc64, ia64,
-s390x and arm architectures.
+s390x, arm and arm64 architectures.
When the system kernel boots, it reserves a small section of memory for
the dump-capture kernel. This ensures that ongoing Direct Memory Access
@@ -249,6 +249,29 @@ Dump-capture kernel config options (Arch Dependent, arm)
AUTO_ZRELADDR=y
+Dump-capture kernel config options (Arch Dependent, arm64)
+----------------------------------------------------------
+
+1) Disable symmetric multi-processing support under "Processor type and
+ features":
+
+ CONFIG_SMP=n
+
+ (If CONFIG_SMP=y, then specify maxcpus=1 on the kernel command line
+ when loading the dump-capture kernel, see section "Load the Dump-capture
+ Kernel".)
SMP is now forced on, so please update this text.
OK, I will fix it.
+2) The maximum memory size on the dump-capture kernel must be limited by
+ specifying:
+
+ mem=X[MG]
+
+ where X should be less than or equal to the size in "crashkernel="
+ boot parameter. Kexec-tools will automatically add this.
+
+3) Currently, kvm will not be enabled on the dump-capture kernel even
+ if it is configured.
+
Extended crashkernel syntax
===========================
@@ -312,6 +335,8 @@ Boot into System Kernel
any space below the alignment point may be overwritten by the dump-capture
kernel,
which means it is possible that the vmcore is not that precise as expected.
+ On arm64, use "crashkernel=Y[@X]". Note that the start address of
+ the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
Load the Dump-capture Kernel
============================
@@ -334,6 +359,8 @@ For s390x:
- Use image or bzImage
For arm:
- Use zImage
+For arm64:
+ - Use vmlinux
What? Why doesn't Image work?
Actually it depends on kexec-tools, not the kernel.
Initially Geoff implemented vmlinux support only, then
recently Pratyush (RedHat) gave us a patch for "Image" support.
So now Image should work.
-Takahiro AKASHI
Will
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