From: chenzhou <chenzhou10@huawei.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: <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>,
<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>
Subject: Re: [PATCH v12 9/9] kdump: update Documentation about crashkernel
Date: Tue, 6 Oct 2020 10:10:54 +0800 [thread overview]
Message-ID: <8644712d-1331-1efc-1cd2-6da8640145b7@huawei.com> (raw)
In-Reply-To: <20201005171936.GD14576@gaia>
Hi Catalin,
On 2020/10/6 1:19, Catalin Marinas wrote:
> On Mon, Sep 07, 2020 at 09:47:45PM +0800, Chen Zhou wrote:
>> 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
> [...]
>> @@ -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.
> I don't think we should mention non-RPi4 explicitly here. I don't even
> understand what the suggestion is since the only way is to disable
> ZONE_DMA in the kernel config. I'd just stick to ZONE_DMA description
> here.
How about like this:
If the kernel config ZONE_DMA is disabled, just try low allocation in DMA32 zone
and high allocation above DMA32 zone.
Thanks,
Chen Zhou
>
>> + 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.
> Same here, unclear what "change DMA zone to DMA32 zone" means.
>
>> 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.
> And again here.
>
next prev parent reply other threads:[~2020-10-06 2:11 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 ` [PATCH v12 9/9] kdump: update Documentation about crashkernel Chen Zhou
2020-10-05 17:19 ` Catalin Marinas
2020-10-06 2:10 ` chenzhou [this message]
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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