On 2022/6/17 10:40, Baoquan He wrote:
> On 06/13/22 at 04:09pm, Zhen Lei wrote:
>> To be consistent with the implementation of x86 and improve cross-platform
>> user experience. Try to allocate at least 256 MiB low memory automatically
>> when crashkernel=Y,low is not specified.
>
> This should correspond to the case that crashkernel=,high is explicitly
> specified, while crashkenrel=,low is omitted. It could be better to
> mention these.
Okay, I'll update the description in the next version.
>
> Otherwise, this looks good to me.
>
>>
>> Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
>> ---
>> Documentation/admin-guide/kernel-parameters.txt | 8 +-------
>> arch/arm64/mm/init.c | 12 +++++++++++-
>> 2 files changed, 12 insertions(+), 8 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index 8090130b544b070..61b179232b68001 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -843,7 +843,7 @@
>> available.
>> It will be ignored if crashkernel=X is specified.
>> crashkernel=size[KMG],low
>> - [KNL, X86-64] range under 4G. When crashkernel=X,high
>> + [KNL, X86-64, ARM64] range under 4G. When crashkernel=X,high
> ~~~~ exceeds 80 characters, it should be OK.
>
>> 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
>> @@ -857,12 +857,6 @@
>> It will be ignored when crashkernel=X,high is not used
>> or memory reserved is below 4G.
>>
>> - [KNL, ARM64] range in low memory.
>> - This one lets the user specify a low range in the
>> - DMA zone for the crash dump kernel.
>> - It will be ignored when crashkernel=X,high is not used
>> - or memory reserved is located in the DMA zones.
>> -
>> cryptomgr.notests
>> [KNL] Disable crypto self-tests
>>
>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
>> index 339ee84e5a61a0b..5390f361208ccf7 100644
>> --- a/arch/arm64/mm/init.c
>> +++ b/arch/arm64/mm/init.c
>> @@ -96,6 +96,14 @@ phys_addr_t __ro_after_init arm64_dma_phys_limit = PHYS_MASK + 1;
>> #define CRASH_ADDR_LOW_MAX arm64_dma_phys_limit
>> #define CRASH_ADDR_HIGH_MAX (PHYS_MASK + 1)
>>
>> +/*
>> + * This is an empirical value in x86_64 and taken here directly. Please
>> + * refer to the code comment in reserve_crashkernel_low() of x86_64 for more
>> + * details.
>> + */
>> +#define DEFAULT_CRASH_KERNEL_LOW_SIZE \
>> + max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20)
>> +
>> static int __init reserve_crashkernel_low(unsigned long long low_size)
>> {
>> unsigned long long low_base;
>> @@ -147,7 +155,9 @@ static void __init reserve_crashkernel(void)
>> * is not allowed.
>> */
>> ret = parse_crashkernel_low(cmdline, 0, &crash_low_size, &crash_base);
>> - if (ret && (ret != -ENOENT))
>> + if (ret == -ENOENT)
>> + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
>> + else if (ret)
>> return;
>>
>> crash_max = CRASH_ADDR_HIGH_MAX;
>> --
>> 2.25.1
>>
>
> .
>
--
Regards,
Zhen Lei
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