From: Baoquan He <bhe@redhat.com>
To: Chen Jiahao <chenjiahao16@huawei.com>
Cc: linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org,
kexec@lists.infradead.org, linux-doc@vger.kernel.org,
paul.walmsley@sifive.com, palmer@dabbelt.com,
conor.dooley@microchip.com, guoren@kernel.org, heiko@sntech.de,
bjorn@rivosinc.com, alex@ghiti.fr, akpm@linux-foundation.org,
atishp@rivosinc.com, thunder.leizhen@huawei.com,
horms@kernel.org
Subject: Re: [PATCH -next v7 0/2] support allocating crashkernel above 4G explicitly on riscv
Date: Fri, 7 Jul 2023 08:53:52 +0800 [thread overview]
Message-ID: <ZKdiIGRAQYx9zILj@MiWiFi-R3L-srv> (raw)
In-Reply-To: <20230704212327.1687310-1-chenjiahao16@huawei.com>
On 07/04/23 at 09:23pm, Chen Jiahao wrote:
> On riscv, the current crash kernel allocation logic is trying to
> allocate within 32bit addressible memory region by default, if
> failed, try to allocate without 4G restriction.
>
> In need of saving DMA zone memory while allocating a relatively large
> crash kernel region, allocating the reserved memory top down in
> high memory, without overlapping the DMA zone, is a mature solution.
> Hence this patchset introduces the parameter option crashkernel=X,[high,low].
>
> One can reserve the crash kernel from high memory above DMA zone range
> by explicitly passing "crashkernel=X,high"; or reserve a memory range
> below 4G with "crashkernel=X,low". Besides, there are few rules need
> to take notice:
> 1. "crashkernel=X,[high,low]" will be ignored if "crashkernel=size"
> is specified.
> 2. "crashkernel=X,low" is valid only when "crashkernel=X,high" is passed
> and there is enough memory to be allocated under 4G.
> 3. When allocating crashkernel above 4G and no "crashkernel=X,low" is
> specified, a 128M low memory will be allocated automatically for
> swiotlb bounce buffer.
> See Documentation/admin-guide/kernel-parameters.txt for more information.
>
> To verify loading the crashkernel, adapted kexec-tools is attached below:
> https://github.com/chenjh005/kexec-tools/tree/build-test-riscv-v2
>
> Following test cases have been performed as expected:
> 1) crashkernel=256M //low=256M
> 2) crashkernel=1G //low=1G
> 3) crashkernel=4G //high=4G, low=128M(default)
> 4) crashkernel=4G crashkernel=256M,high //high=4G, low=128M(default), high is ignored
> 5) crashkernel=4G crashkernel=256M,low //high=4G, low=128M(default), low is ignored
> 6) crashkernel=4G,high //high=4G, low=128M(default)
> 7) crashkernel=256M,low //low=0M, invalid
> 8) crashkernel=4G,high crashkernel=256M,low //high=4G, low=256M
> 9) crashkernel=4G,high crashkernel=4G,low //high=0M, low=0M, invalid
> 10) crashkernel=512M@0xd0000000 //low=512M
> 11) crashkernel=1G,high crashkernel=0M,low //high=1G, low=0M
The series looks good to me, thanks.
Acked-by: Baoquan He <bhe@redhat.com>
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prev parent reply other threads:[~2023-07-07 0:54 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-04 21:23 [PATCH -next v7 0/2] support allocating crashkernel above 4G explicitly on riscv Chen Jiahao
2023-07-04 21:23 ` [PATCH -next v7 1/2] riscv: kdump: Implement crashkernel=X,[high,low] Chen Jiahao
2023-07-04 21:23 ` [PATCH -next v7 2/2] docs: kdump: Update the crashkernel description for riscv Chen Jiahao
2023-07-07 0:53 ` Baoquan He [this message]
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