Re: [PATCH -next v3 0/2] support allocating crashkernel above 4G explicitly on riscv
On 2023/4/7 20:05, Simon Horman wrote: On Fri, Apr 07, 2023 at 06:02:04AM +0800, 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 Are you planning to submit the kexec-tools patches too? Yes, but current adaptation is a little informal. I will submit them later after further tests. BR, Jiahao ___ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
Re: [PATCH -next v3 0/2] support allocating crashkernel above 4G explicitly on riscv
On Fri, Apr 07, 2023 at 06:02:04AM +0800, 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 Are you planning to submit the kexec-tools patches too? ___ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
[PATCH -next v3 0/2] support allocating crashkernel above 4G explicitly on riscv
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@0xd000 //low=512M 11) crashkernel=1G@0xe000//high=0M, low=0M, no enough low memory, failed 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 | 74 +-- 3 files changed, 82 insertions(+), 12 deletions(-) -- 2.31.1 ___ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
