Unverified Commit 33f0dd97 authored by Chen Jiahao's avatar Chen Jiahao Committed by Palmer Dabbelt
Browse files

docs: kdump: Update the crashkernel description for riscv 



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.

Signed-off-by: default avatarChen Jiahao <chenjiahao16@huawei.com>
Reviewed-by: default avatarGuo Ren <guoren@kernel.org>
Reviewed-by: default avatarSimon Horman <horms@kernel.org>
Reviewed-by: default avatarZhen Lei <thunder.leizhen@huawei.com>
Acked-by: default avatarBaoquan He <bhe@redhat.com>
Link: https://lore.kernel.org/r/20230726175000.2536220-3-chenjiahao16@huawei.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 5882e5ac

Documentation/admin-guide/kernel-parameters.txt

+8 −7
Original line number Diff line number Diff line
@@ -862,7 +862,7 @@ 
			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.
@@ -875,14 +875,14 @@ 
			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
@@ -893,6 +893,7 @@ 
			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.