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.leiz...@huawei.com>
>
> Signed-off-by: Chen Jiahao <chenjiaha...@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
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