Re: [PATCH v21 5/5] docs: kdump: Update the crashkernel description for arm64

From: Baoquan He <bhe@redhat.com>
To: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
	linux-kernel@vger.kernel.org, Dave Young <dyoung@redhat.com>,
	Vivek Goyal <vgoyal@redhat.com>,
	Eric Biederman <ebiederm@xmission.com>,
	kexec@lists.infradead.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	Rob Herring <robh+dt@kernel.org>,
	Frank Rowand <frowand.list@gmail.com>,
	devicetree@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
	linux-doc@vger.kernel.org, Randy Dunlap <rdunlap@infradead.org>,
	Feng Zhou <zhoufeng.zf@bytedance.com>,
	Kefeng Wang <wangkefeng.wang@huawei.com>,
	Chen Zhou <dingguo.cz@antgroup.com>,
	John Donnelly <John.p.donnelly@oracle.com>,
	Dave Kleikamp <dave.kleikamp@oracle.com>
Subject: Re: [PATCH v21 5/5] docs: kdump: Update the crashkernel description for arm64
Date: Tue, 15 Mar 2022 19:59:33 +0800	[thread overview]
Message-ID: <YjB/pTWF8wKcATaq@MiWiFi-R3L-srv> (raw)
In-Reply-To: <20220227030717.1464-6-thunder.leizhen@huawei.com>

On 02/27/22 at 11:07am, Zhen Lei wrote:
> Now arm64 has added support for "crashkernel=X,high" and
> "crashkernel=Y,low", and implements "crashkernel=X[@offset]" in the
> same way as x86. So update the Documentation.
> 
> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>

Looks good to me, thx.

Acked-by: Baoquan He <bhe@redhat.com>

> ---
>  Documentation/admin-guide/kernel-parameters.txt | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index f5a27f067db9ed9..63098786c93828c 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -789,7 +789,7 @@
>  			memory region [offset, offset + size] for that kernel
>  			image. If '@offset' is omitted, then a suitable offset
>  			is selected automatically.
> -			[KNL, X86-64] Select a region under 4G first, and
> +			[KNL, X86-64, ARM64] Select a region under 4G first, and
>  			fall back to reserve region above 4G when '@offset'
>  			hasn't been specified.
>  			See Documentation/admin-guide/kdump/kdump.rst for further details.
> @@ -802,20 +802,20 @@
>  			Documentation/admin-guide/kdump/kdump.rst for an example.
>  
>  	crashkernel=size[KMG],high
> -			[KNL, X86-64] range could be above 4G. Allow kernel
> +			[KNL, X86-64, ARM64] range could be above 4G. Allow kernel
>  			to allocate physical memory region from top, so could
>  			be above 4G if system have more than 4G ram installed.
>  			Otherwise memory region will be allocated below 4G, if
>  			available.
>  			It will be ignored if crashkernel=X is specified.
>  	crashkernel=size[KMG],low
> -			[KNL, X86-64] range under 4G. When crashkernel=X,high
> +			[KNL, X86-64, ARM64] range under 4G. When crashkernel=X,high
>  			is passed, kernel could allocate physical memory region
>  			above 4G, that cause second kernel crash on system
>  			that require some amount of low memory, e.g. swiotlb
>  			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
> +			devices won't run out. Kernel would try to allocate
>  			at least 256M below 4G automatically.
>  			This one let user to specify own low range under 4G
>  			for second kernel instead.
> -- 
> 2.25.1
> 

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