From: Chen Zhou <chenzhou10@huawei.com>
To: <catalin.marinas@arm.com>, <will@kernel.org>,
<james.morse@arm.com>, <tglx@linutronix.de>, <mingo@redhat.com>,
<dyoung@redhat.com>, <bhe@redhat.com>, <corbet@lwn.net>,
<John.P.donnelly@oracle.com>, <prabhakar.pkin@gmail.com>,
<bhsharma@redhat.com>
Cc: <horms@verge.net.au>, <robh+dt@kernel.org>, <arnd@arndb.de>,
<nsaenzjulienne@suse.de>, <linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <kexec@lists.infradead.org>,
<linux-doc@vger.kernel.org>, <guohanjun@huawei.com>,
<xiexiuqi@huawei.com>, <huawei.libin@huawei.com>,
<wangkefeng.wang@huawei.com>, <chenzhou10@huawei.com>
Subject: [PATCH v12 9/9] kdump: update Documentation about crashkernel
Date: Mon, 7 Sep 2020 21:47:45 +0800 [thread overview]
Message-ID: <20200907134745.25732-10-chenzhou10@huawei.com> (raw)
In-Reply-To: <20200907134745.25732-1-chenzhou10@huawei.com>
For arm64, the behavior of crashkernel=X has been changed, which
tries low allocation in DMA zone, 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.
"crashkernel=Y,low" can be used to allocate specified size low memory
in DMA zone.
For non-RPi4 platforms, change DMA zone memtioned above to DMA32 zone.
For x86 and arm64, we introduce threshold for the required memory.
if required size X is too large and leads to very little free low
memory after low allocation, the system may not work well.
So add a threshold and go for high allocation directly if the required
size is too large. The threshold is set as the half of low memory.
So update the Documentation.
Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
---
Documentation/admin-guide/kdump/kdump.rst | 25 ++++++++++++++++---
.../admin-guide/kernel-parameters.txt | 13 ++++++++--
2 files changed, 33 insertions(+), 5 deletions(-)
diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
index 2da65fef2a1c..549611abc581 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 +325,18 @@ 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, and
+ fall back to high allocation if it fails. And go for high allocation
+ directly if the required size is too large.
+ 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.
+ "crashkernel=Y,low" can be used to allocate specified size low memory
+ in DMA zone.
+ For non-RPi4 platforms, change DMA zone memtioned above to DMA32 zone.
+ 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 a1068742a6df..f7df572d8f64 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -727,6 +727,10 @@
[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, fall back
+ to high allocation if it fails when '@offset' hasn't been
+ specified. For non-RPi4 platforms, change DMA zone to
+ DMA32 zone.
See Documentation/admin-guide/kdump/kdump.rst for further details.
crashkernel=range1:size1[,range2:size2,...][@offset]
@@ -743,6 +747,8 @@
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
@@ -751,13 +757,16 @@
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. For non-RPi4 platforms, change DMA zone
+ to DMA32 zone.
cryptomgr.notests
[KNL] Disable crypto self-tests
--
2.20.1
next prev parent reply other threads:[~2020-09-07 17:22 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-07 13:47 [PATCH v12 0/9] support reserving crashkernel above 4G on arm64 kdump Chen Zhou
2020-09-07 13:47 ` [PATCH v12 1/9] x86: kdump: move CRASH_ALIGN to 2M Chen Zhou
2020-09-08 1:21 ` Dave Young
2020-09-08 3:19 ` chenzhou
2020-09-07 13:47 ` [PATCH v12 2/9] x86: kdump: make the lower bound of crash kernel reservation consistent Chen Zhou
2020-09-07 13:47 ` [PATCH v12 3/9] x86: kdump: use macro CRASH_ADDR_LOW_MAX in functions reserve_crashkernel[_low]() Chen Zhou
2020-09-18 3:01 ` Dave Young
2020-09-18 3:57 ` chenzhou
2020-09-18 5:26 ` Dave Young
2020-09-18 7:25 ` Baoquan He
2020-09-18 8:59 ` chenzhou
2020-09-18 9:06 ` chenzhou
2020-10-05 17:20 ` Catalin Marinas
2020-09-07 13:47 ` [PATCH v12 4/9] x86: kdump: move reserve_crashkernel[_low]() into crash_core.c Chen Zhou
2020-09-07 13:47 ` [PATCH v12 5/9] arm64: kdump: introduce some macroes for crash kernel reservation Chen Zhou
2020-09-07 13:47 ` [PATCH v12 6/9] arm64: kdump: reimplement crashkernel=X Chen Zhou
2020-10-05 17:16 ` Catalin Marinas
2020-10-06 1:30 ` chenzhou
2020-09-07 13:47 ` [PATCH v12 7/9] kdump: add threshold for the required memory Chen Zhou
2020-10-05 17:12 ` Catalin Marinas
2020-10-06 1:34 ` chenzhou
2020-09-07 13:47 ` [PATCH v12 8/9] arm64: kdump: add memory for devices by DT property linux,usable-memory-range Chen Zhou
2020-09-07 13:47 ` Chen Zhou [this message]
2020-10-05 17:19 ` [PATCH v12 9/9] kdump: update Documentation about crashkernel Catalin Marinas
2020-10-06 2:10 ` chenzhou
2020-10-07 16:24 ` Catalin Marinas
2020-09-12 11:44 ` [PATCH v12 0/9] support reserving crashkernel above 4G on arm64 kdump John Donnelly
2020-10-05 17:09 ` Catalin Marinas
2020-10-05 17:42 ` Bhupesh Sharma
2020-10-06 1:48 ` chenzhou
2020-10-06 18:00 ` Catalin Marinas
2020-10-07 7:07 ` Bhupesh Sharma
2020-10-07 16:33 ` Catalin Marinas
2020-10-19 2:43 ` chenzhou
2020-09-15 7:16 ` chenzhou
2020-09-23 17:47 ` John Donnelly
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