From: Chen Zhou <chenzhou10@huawei.com>
To: <tglx@linutronix.de>, <mingo@redhat.com>, <dyoung@redhat.com>,
<bhe@redhat.com>, <catalin.marinas@arm.com>, <will@kernel.org>,
<corbet@lwn.net>, <John.P.donnelly@oracle.com>,
<bhsharma@redhat.com>, <prabhakar.pkin@gmail.com>
Cc: <horms@verge.net.au>, <robh+dt@kernel.org>, <arnd@arndb.de>,
<nsaenzjulienne@suse.de>, <james.morse@arm.com>,
<linux-kernel@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<kexec@lists.infradead.org>, <linux-doc@vger.kernel.org>,
<chenzhou10@huawei.com>, <xiexiuqi@huawei.com>,
<guohanjun@huawei.com>, <huawei.libin@huawei.com>,
<wangkefeng.wang@huawei.com>,
John Donnelly <John.p.donnelly@oracle.com>
Subject: [PATCH v13 8/8] kdump: update Documentation about crashkernel
Date: Sat, 31 Oct 2020 15:44:37 +0800 [thread overview]
Message-ID: <20201031074437.168008-9-chenzhou10@huawei.com> (raw)
In-Reply-To: <20201031074437.168008-1-chenzhou10@huawei.com>
For arm64, the behavior of crashkernel=X has been changed, which
tries low allocation in DMA zone or DMA32 zone if CONFIG_ZONE_DMA
is disabled, and fall back to high allocation if it fails.
We can also use "crashkernel=X,high" to select a high region above
DMA zone, which also tries to allocate at least 256M low memory in
DMA zone automatically (or the DMA32 zone if CONFIG_ZONE_DMA is disabled).
"crashkernel=Y,low" can be used to allocate specified size low memory.
So update the Documentation.
Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Tested-by: John Donnelly <John.p.donnelly@oracle.com>
---
Documentation/admin-guide/kdump/kdump.rst | 23 ++++++++++++++++---
.../admin-guide/kernel-parameters.txt | 12 ++++++++--
2 files changed, 30 insertions(+), 5 deletions(-)
diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
index 75a9dd98e76e..bde5f994d185 100644
--- a/Documentation/admin-guide/kdump/kdump.rst
+++ b/Documentation/admin-guide/kdump/kdump.rst
@@ -299,7 +299,16 @@ 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=X" to select a region under 4G first, and
+ fall back to reserve region above 4G. And go for high allocation
+ directly if the required size is too large.
+ 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.
+ Use "crashkernel=Y@X" if you really have to reserve memory from specified
+ start address X.
On ppc64, use "crashkernel=128M@32M".
@@ -316,8 +325,16 @@ 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
- the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
+ On arm64, use "crashkernel=X" to try low allocation in DMA zone (or
+ DMA32 zone if CONFIG_ZONE_DMA is disabled), and fall back to high
+ allocation if it fails.
+ We can also use "crashkernel=X,high" to select a high region above
+ DMA zone, which also tries to allocate at least 256M low memory in
+ DMA zone automatically (or the DMA32 zone if CONFIG_ZONE_DMA is disabled).
+ "crashkernel=Y,low" can be used to allocate specified size low memory.
+ Use "crashkernel=Y@X" if you really have to reserve memory from
+ specified start address X. Note that the start address of the kernel,
+ X if explicitly specified, must be aligned to 2MiB (0x200000).
Load the Dump-capture Kernel
============================
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 526d65d8573a..b2955d9379e8 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -738,6 +738,9 @@
[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] Try low allocation in DMA zone (or DMA32 zone
+ if CONFIG_ZONE_DMA is disabled), fall back to high allocation
+ if it fails when '@offset' hasn't been specified.
See Documentation/admin-guide/kdump/kdump.rst for further details.
crashkernel=range1:size1[,range2:size2,...][@offset]
@@ -754,6 +757,8 @@
Otherwise memory region will be allocated below 4G, if
available.
It will be ignored if crashkernel=X is specified.
+ [KNL, arm64] range in high memory.
+ Allow kernel to allocate physical memory region from top.
crashkernel=size[KMG],low
[KNL, X86-64] range under 4G. When crashkernel=X,high
is passed, kernel could allocate physical memory region
@@ -762,13 +767,16 @@
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 in low memory.
+ This one let user to specify a low range in DMA zone for
+ crash dump kernel (or the DMA32 zone if CONFIG_ZONE_DMA
+ is disabled).
cryptomgr.notests
[KNL] Disable crypto self-tests
--
2.20.1
next prev parent reply other threads:[~2020-10-31 7:39 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-31 7:44 [PATCH v13 0/8] support reserving crashkernel above 4G on arm64 kdump Chen Zhou
2020-10-31 7:44 ` [PATCH v13 1/8] x86: kdump: replace the hard-coded alignment with macro CRASH_ALIGN Chen Zhou
2020-11-11 1:38 ` Baoquan He
2020-11-11 13:26 ` chenzhou
2020-11-12 7:58 ` Mike Rapoport
2020-11-12 8:12 ` chenzhou
2020-10-31 7:44 ` [PATCH v13 2/8] x86: kdump: make the lower bound of crash kernel reservation consistent Chen Zhou
2020-10-31 7:44 ` [PATCH v13 3/8] x86: kdump: use macro CRASH_ADDR_LOW_MAX in functions reserve_crashkernel() Chen Zhou
2020-10-31 7:44 ` [PATCH v13 4/8] x86: kdump: move reserve_crashkernel[_low]() into crash_core.c Chen Zhou
2020-11-12 8:11 ` Mike Rapoport
2020-11-12 13:01 ` chenzhou
2020-10-31 7:44 ` [PATCH v13 5/8] arm64: kdump: introduce some macroes for crash kernel reservation Chen Zhou
2020-10-31 7:44 ` [PATCH v13 6/8] arm64: kdump: reimplement crashkernel=X Chen Zhou
2020-11-11 1:59 ` Baoquan He
2020-11-11 13:27 ` chenzhou
2020-11-11 13:54 ` Baoquan He
2020-11-12 8:25 ` Mike Rapoport
2020-11-12 8:36 ` Baoquan He
2020-11-12 13:11 ` chenzhou
2020-10-31 7:44 ` [PATCH v13 7/8] arm64: kdump: add memory for devices by DT property linux,usable-memory-range Chen Zhou
2020-10-31 7:44 ` Chen Zhou [this message]
2020-11-09 12:34 ` [PATCH v13 0/8] support reserving crashkernel above 4G on arm64 kdump chenzhou
2020-11-11 3:01 ` Baoquan He
2020-11-11 13:29 ` chenzhou
2020-11-11 19:41 ` Bhupesh SHARMA
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