On 12/17/19 8:07 PM, Chen Zhou wrote:
Hi
See inline below
Hi all,
Friendly ping...
On 2019/8/30 15:11, Chen Zhou wrote:
I am busy with other things, so it was a long time before this version was
released.
This patch series enable reserving crashkernel above 4G in arm64.
There are following issues in arm64 kdump:
1. We use crashkernel=X to reserve crashkernel below 4G, which will fail
when there is no enough low memory.
2. Currently, crashkernel=Y@X can be used to reserve crashkernel above 4G,
in this case, if swiotlb or DMA buffers are requierd, crash dump kernel
will boot failure because there is no low memory available for allocation.
To solve these issues, introduce crashkernel=X,low to reserve specified
size low memory.
Crashkernel=X tries to reserve memory for the crash dump kernel under
4G. If crashkernel=Y,low is specified simultaneously, reserve spcified
size low memory for crash kdump kernel devices firstly and then reserve
memory above 4G.
When crashkernel is reserved above 4G in memory, that is, crashkernel=X,low
is specified simultaneously, kernel should reserve specified size low memory
for crash dump kernel devices. So there may be two crash kernel regions, one
is below 4G, the other is above 4G.
In order to distinct from the high region and make no effect to the use of
kexec-tools, rename the low region as "Crash kernel (low)", and add DT property
"linux,low-memory-range" to crash dump kernel's dtb to pass the low region.
Hi ,
I have found that 5.4 Arm kernels can safely use 768M crashkernel size
for " standard" crash dumps that write a minimal vmcore to local
storage. While "standard" may vary, I say that is default out of box
delivery.
If you a introduce more elaborate setup that use networking and NFS, a
larger crashkernel is needed, and since 1024MB size is not available, I
found using the 1st available range above 4GB on node-0 works:
Set the crash dump to be in the 1st 35G region on node-0 after 4G :
.
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000090000000-0x0000000091ffffff]
[ 0.000000] node 0: [mem 0x0000000092000000-0x00000000928bffff]
[ 0.000000] node 0: [mem 0x00000000928c0000-0x00000000fff9ffff]
[ 0.000000] node 0: [mem 0x00000000fffa0000-0x00000000ffffffff]
[ 0.000000] node 0: [mem 0x0000000880000000-0x0000000fffffffff]
[ 0.000000] node 0: [mem 0x0000008800000000-0x000000bff702ffff].
0x0000008800000000 is the 1st region @35G
crashkernel=2048M@35G
yields :
[ 0.000000] crashkernel reserved: 0x00000008c0000000-
0x0000000940000000 @ (2048 MB)
Now we have very large Arm server class systems with GB of memory so 2GB
crashkernel is not much of an impact
No modifications are needed.
I submitted a RFC awhile back to add crashkernel=auto upstream that
hasn't been reviewed yet that could be used to set various Arm crash
sizes like x86 does.
Besides, we need to modify kexec-tools:
arm64: kdump: add another DT property to crash dump kernel's dtb(see [1])
The previous changes and discussions can be retrieved from:
Changes since [v5]
- Move reserve_crashkernel_low() into kernel/crash_core.c.
- Delete crashkernel=X,high.
- Modify crashkernel=X,low.
If crashkernel=X,low is specified simultaneously, reserve spcified size low
memory for crash kdump kernel devices firstly and then reserve memory above 4G.
In addition, rename crashk_low_res as "Crash kernel (low)" for arm64, and then
pass to crash dump kernel by DT property "linux,low-memory-range".
- Update Documentation/admin-guide/kdump/kdump.rst.
Changes since [v4]
- Reimplement memblock_cap_memory_ranges for multiple ranges by Mike.
Changes since [v3]
- Add memblock_cap_memory_ranges back for multiple ranges.
- Fix some compiling warnings.
Changes since [v2]
- Split patch "arm64: kdump: support reserving crashkernel above 4G" as
two. Put "move reserve_crashkernel_low() into kexec_core.c" in a separate
patch.
Changes since [v1]:
- Move common reserve_crashkernel_low() code into kernel/kexec_core.c.
- Remove memblock_cap_memory_ranges() i added in v1 and implement that
in fdt_enforce_memory_region().
There are at most two crash kernel regions, for two crash kernel regions
case, we cap the memory range [min(regs[*].start), max(regs[*].end)]
and then remove the memory range in the middle.
[1]: https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.infradead.org_pipermail_kexec_2019-2DAugust_023569.html&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=t2fPg9D87F7D8jm0_3CG9yoiIKdRg4qc_thBw4bzMhc&m=ZAC6UYbT-3qLR3Dvevd09m6neWWzGWSphuvXXlXow68&s=9tn9kUBabiuYhVtXauANSDGaISnCnHLYcAUQgsPBFxs&e=
[v1]: https://urldefense.proofpoint.com/v2/url?u=https-3A__lkml.org_lkml_2019_4_2_1174&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=t2fPg9D87F7D8jm0_3CG9yoiIKdRg4qc_thBw4bzMhc&m=ZAC6UYbT-3qLR3Dvevd09m6neWWzGWSphuvXXlXow68&s=F-lM7II2cuMF_sK3b6-QhSbWM3X-pI_WZEs0sZitS7A&e=
[v2]: https://urldefense.proofpoint.com/v2/url?u=https-3A__lkml.org_lkml_2019_4_9_86&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=t2fPg9D87F7D8jm0_3CG9yoiIKdRg4qc_thBw4bzMhc&m=ZAC6UYbT-3qLR3Dvevd09m6neWWzGWSphuvXXlXow68&s=5Y-S6sqMTklHkOQsNtjTX3C7pV05BjKLGhJVfMHEvDs&e=
[v3]: https://urldefense.proofpoint.com/v2/url?u=https-3A__lkml.org_lkml_2019_4_9_306&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=t2fPg9D87F7D8jm0_3CG9yoiIKdRg4qc_thBw4bzMhc&m=ZAC6UYbT-3qLR3Dvevd09m6neWWzGWSphuvXXlXow68&s=cWn4zSRQupaZ3jjz4eDvD-pNkoLyL_hsZoRx4yJoD0c&e=
[v4]: https://urldefense.proofpoint.com/v2/url?u=https-3A__lkml.org_lkml_2019_4_15_273&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=t2fPg9D87F7D8jm0_3CG9yoiIKdRg4qc_thBw4bzMhc&m=ZAC6UYbT-3qLR3Dvevd09m6neWWzGWSphuvXXlXow68&s=Nslk4RJKIyIuT0IoQoolXNjupEDXplPhQQwnTSoXNWE&e=
[v5]: https://urldefense.proofpoint.com/v2/url?u=https-3A__lkml.org_lkml_2019_5_6_1360&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=t2fPg9D87F7D8jm0_3CG9yoiIKdRg4qc_thBw4bzMhc&m=ZAC6UYbT-3qLR3Dvevd09m6neWWzGWSphuvXXlXow68&s=HJVAM6sCxV2DnNg5d4pw8WPqtkmQnKvztEmkSIgtQ5M&e=
Chen Zhou (4):
x86: kdump: move reserve_crashkernel_low() into crash_core.c
arm64: kdump: reserve crashkenel above 4G for crash dump kernel
arm64: kdump: add memory for devices by DT property, low-memory-range
kdump: update Documentation about crashkernel on arm64
Documentation/admin-guide/kdump/kdump.rst | 13 ++++-
Documentation/admin-guide/kernel-parameters.txt | 12 ++++-
arch/arm64/include/asm/kexec.h | 3 ++
arch/arm64/kernel/setup.c | 8 ++-
arch/arm64/mm/init.c | 61 +++++++++++++++++++++--
arch/x86/include/asm/kexec.h | 3 ++
arch/x86/kernel/setup.c | 65 +++----------------------
include/linux/crash_core.h | 4 ++
include/linux/kexec.h | 1 -
kernel/crash_core.c | 65 +++++++++++++++++++++++++
10 files changed, 168 insertions(+), 67 deletions(-)
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--
Thank You,
John
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