Now we support crashkernel=X,[low] on arm64, update the Documentation.
We could use parameters "crashkernel=X crashkernel=Y,low" to reserve
memory above 4G.
Signed-off-by: Chen Zhou <chenzhou10@xxxxxxxxxx>
Tested-by: John Donnelly <John.p.donnelly@xxxxxxxxxx>
Tested-by: Prabhakar Kushwaha <pkushwaha@xxxxxxxxxxx>
---
Documentation/admin-guide/kdump/kdump.rst | 13 +++++++++++--
Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++++++++--
2 files changed, 26 insertions(+), 4 deletions(-)
diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
index 2da65fef2a1c..6ba294d425c9 100644
--- a/Documentation/admin-guide/kdump/kdump.rst
+++ b/Documentation/admin-guide/kdump/kdump.rst
@@ -299,7 +299,13 @@ Boot into System Kernel
"crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
- On x86 and x86_64, use "crashkernel=64M@16M".
+ On x86 use "crashkernel=64M@16M".
+
+ On x86_64, use "crashkernel=Y[@X]" to select a region under 4G first, and
+ fall back to reserve region above 4G when '@offset' hasn't been specified.
+ We can also use "crashkernel=X,high" to select a region above 4G, which
+ also tries to allocate at least 256M below 4G automatically and
+ "crashkernel=Y,low" can be used to allocate specified size low memory.
On ppc64, use "crashkernel=128M@32M".
@@ -316,8 +322,11 @@ Boot into System Kernel
kernel will automatically locate the crash kernel image within the
first 512MB of RAM if X is not given.
- On arm64, use "crashkernel=Y[@X]". Note that the start address of
+ On arm64, use "crashkernel=Y[@X]". Note that the start address of
the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
+ If crashkernel=Z,low is specified simultaneously, reserve spcified size
+ low memory for crash kdump kernel devices firstly and then reserve memory
+ above 4G.
Load the Dump-capture Kernel
============================
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index fb95fad81c79..335431a351c0 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -722,6 +722,9 @@
[KNL, x86_64] select a region under 4G first, and
fall back to reserve region above 4G when '@offset'
hasn't been specified.
+ [KNL, arm64] If crashkernel=X,low is specified, reserve
+ spcified size low memory for crash kdump kernel devices
+ firstly, and then reserve memory above 4G.
See Documentation/admin-guide/kdump/kdump.rst for further details.
crashkernel=range1:size1[,range2:size2,...][@offset]
@@ -746,13 +749,23 @@
requires at least 64M+32K low memory, also enough extra
low memory is needed to make sure DMA buffers for 32-bit
devices won't run out. Kernel would try to allocate at
- at least 256M below 4G automatically.
+ least 256M below 4G automatically.
This one let user to specify own low range under 4G
for second kernel instead.
0: to disable low allocation.
It will be ignored when crashkernel=X,high is not used
or memory reserved is below 4G.
-
+ [KNL, arm64] range under 4G.
+ This one let user to specify own low range under 4G
+ for crash dump kernel instead.
+ Different with x86_64, kernel allocates specified size
+ physical memory region only when this parameter is specified
+ instead of trying to allocate at least 256M below 4G
+ automatically.
+ This parameter is used along with crashkernel=X when we
+ want to reserve crashkernel above 4G. If there are devices
+ need to use ZONE_DMA in crash dump kernel, it is also
+ a good choice.
cryptomgr.notests
[KNL] Disable crypto self-tests
--
2.20.1
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