Messages in this thread | | | Date | Mon, 10 Apr 2023 17:52:37 +0800 | Subject | Re: [PATCH -next v3 1/2] riscv: kdump: Implement crashkernel=X,[high,low] | From | "chenjiahao (C)" <> |
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On 2023/4/8 10:00, Leizhen (ThunderTown) wrote: > > On 2023/4/7 20:58, Leizhen (ThunderTown) wrote: >> >> On 2023/4/7 20:03, Simon Horman wrote: >>> On Fri, Apr 07, 2023 at 06:02:05AM +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. >>>> Here introduce 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". >>>> >>>> Signed-off-by: Chen Jiahao <chenjiahao16@huawei.com> >>> ... >>> >>>> @@ -1180,14 +1206,37 @@ static void __init reserve_crashkernel(void) >>>> return; >>>> } >>>> >>>> - ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(), >>>> + ret = parse_crashkernel(cmdline, memblock_phys_mem_size(), >>>> &crash_size, &crash_base); >>>> - if (ret || !crash_size) >>>> + if (ret == -ENOENT) { >>>> + /* >>>> + * crashkernel=X,[high,low] can be specified or not, but >>>> + * invalid value is not allowed. >>> nit: Perhaps something like this would be easier to correlate with the >>> code that follows: >>> >>> /* Fallback to crashkernel=X,[high,low] */ >> The description "crashkernel=X,[high,low] can be specified or not" is not >> correct, because crashkernel=X,high must be specified when walking into this >> branch. So use Simon's comments or copy arm64's comments(it's written for >> parse_crashkernel_low()). > I rethink it a little bit, if it's relative to crashkernel=X[@offset], > that's also true. > > Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Sure, The commit should not be ambiguous like this, Simon's comment above is
a better option.
>>> >>>> + */ >>>> + ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base); >>>> + if (ret || !crash_size) >>>> + return; >>>> + >>>> + /* >>>> + * crashkernel=Y,low is valid only when crashkernel=X,high >>>> + * is passed and high memory is reserved successful. >>> nit: s/successful/successfully/ >> Seems like the whole "and high memory is reserved successful" needs to be deleted. >> Only the dependency between the two boot options should be described here, >> regardless of whether their memory is successfully allocated.
The comment here is imprecise, since there is absolutely no check whether
the allocation is successful before "parse_crashkernel_low"
>> >>>> + */ >>>> + ret = parse_crashkernel_low(cmdline, 0, &crash_low_size, &crash_base); >>>> + if (ret == -ENOENT) >>>> + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; >>>> + else if (ret) >>>> + return; >>>> + >>>> + search_start = search_low_max; >>>> + } else if (ret || !crash_size) { >>>> + /* Invalid argument value specified */ >>>> return; >>>> + } >>> ... >>> . >>> BR,
Jiahao
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