Re: [PATCH -next v3 1/2] riscv: kdump: Implement crashkernel=X,[high,low]

chenjiahao (C)
2023-04-10T09:20:38Z

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] */
>
Agreed, this would be more concise and accurate.
>> + */
>> + 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/

I will fix above nits and resend another version later, thanks.

>> + */
>> + 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;
>> + }
> ...