Subject: Re: [PATCH -next 2/2] docs: kdump: Update the crashkernel description
 for riscv
To:     Chen Jiahao <chenjiahao16@huawei.com>, <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>, <bhe@redhat.com>
CC:     <linux-kernel@vger.kernel.org>, <linux-riscv@lists.infradead.org>,
        <kexec@lists.infradead.org>, <linux-doc@vger.kernel.org>
References: <20230320204244.1637821-1-chenjiahao16@huawei.com>
 <20230320204244.1637821-3-chenjiahao16@huawei.com>
From:   "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>
Message-ID: <c3d6caae-39ed-a785-13b5-f36fb96d9a5e@huawei.com>
Date:   Tue, 21 Mar 2023 09:45:51 +0800
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On 2023/3/21 4:42, Chen Jiahao wrote:
> Now "crashkernel=" parameter on riscv has been updated to support
> crashkernel=X,[high,low]. Through which we can reserve memory region
> above/within 32bit addressible DMA zone.
> 
> Here update the parameter description accordingly.

Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>

> 
> Signed-off-by: Chen Jiahao <chenjiahao16@huawei.com>
> ---
>  Documentation/admin-guide/kernel-parameters.txt | 15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 6221a1d057dd..89e26a4864f8 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -843,7 +843,7 @@
>  			memory region [offset, offset + size] for that kernel
>  			image. If '@offset' is omitted, then a suitable offset
>  			is selected automatically.
> -			[KNL, X86-64, ARM64] Select a region under 4G first, and
> +			[KNL, X86-64, ARM64, RISCV] 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.
> @@ -856,14 +856,14 @@
>  			Documentation/admin-guide/kdump/kdump.rst for an example.
>  
>  	crashkernel=size[KMG],high
> -			[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.
> +			[KNL, X86-64, ARM64, RISCV] 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, ARM64] range under 4G. When crashkernel=X,high
> +			[KNL, X86-64, ARM64, RISCV] 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
> @@ -874,6 +874,7 @@
>  			size is	platform dependent.
>  			  --> x86: max(swiotlb_size_or_default() + 8MiB, 256MiB)
>  			  --> arm64: 128MiB
> +			  --> riscv: 128MiB
>  			This one lets the user specify own low range under 4G
>  			for second kernel instead.
>  			0: to disable low allocation.
> 

-- 
Regards,
  Zhen Lei