Messages in this thread | | | Date | Tue, 29 Aug 2023 17:54:35 +0800 | Subject | Re: [PATCH -next v9 0/2] support allocating crashkernel above 4G explicitly on riscv | From | "chenjiahao (C)" <> |
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Hi folks,
This is a friendly ping. Anyone has additional comments on this patch set?
Best regards, Jiahao
On 2023/7/27 1:49, 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 > > Changes since [v9]: > 1. As per Conor's comment, rebase to correct base on riscv/for-next > branch. No code logic changed. > > Changes since [v8]: > 1. Rebase to newest mainline head, not modifying any code logic. > > Changes since [v7]: > 1. Minor refactor: move crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE > into the !high branch when the first allocation fails. Not changing > the result but further align with Arm64 logic, refer to Baoquan's > comment. > 2. Add test case "crashkernel=1G,high crashkernel=0M,low", the result > also matches our expectation. > > Changes since [v6]: > 1. Introduce the "high" flag to mark whether "crashkernel=X,high" > is passed. Fix the retrying logic between "crashkernel=X,high" > case and others when the first allocation attempt fails. > > Changes since [v5]: > 1. Update the crashkernel allocation logic when crashkernel=X,high > is specified. In this case, region above 4G will directly get > reserved as crashkernel, rather than trying lower 32bit allocation > first. > > Changes since [v4]: > 1. Update some imprecise code comments for cmdline parsing. > > Changes since [v3]: > 1. Update to print warning and return explicitly on failure when > crashkernel=size@offset is specified. Not changing the result > in this case but making the logic more straightforward. > 2. Some minor cleanup. > > Changes since [v2]: > 1. Update the allocation logic to ensure the high crashkernel > region is reserved strictly above dma32_phys_limit. > 2. Clean up some minor format problems. > > Chen Jiahao (2): > riscv: kdump: Implement crashkernel=X,[high,low] > docs: kdump: Update the crashkernel description for riscv > > .../admin-guide/kernel-parameters.txt | 15 +-- > arch/riscv/kernel/setup.c | 5 + > arch/riscv/mm/init.c | 93 +++++++++++++++++-- > 3 files changed, 99 insertions(+), 14 deletions(-) >
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