On 2022/5/11 17:06, Baoquan He wrote:
> On 05/11/22 at 11:20am, Zhen Lei wrote:
>> When "crashkernel=X,high" is specified, the specified "crashkernel=Y,low"
>> memory is not required in the following corner cases:
>> 1. If both CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32 are disabled, it means
>> that the devices can access any memory.
>> 2. If the system memory is small, the crash high memory may be allocated
>> from the DMA zones. If that happens, there's no need to allocate
>> another crash low memory because there's already one.
>>
>> Add condition '(crash_base >= CRASH_ADDR_LOW_MAX)' to determine whether
>> the 'high' memory is allocated above DMA zones. Note: when both
>> CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32 are disabled, the entire physical
>> memory is DMA accessible, CRASH_ADDR_LOW_MAX equals 'PHYS_MASK + 1'.
>>
>> Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
>> ---
>> Documentation/admin-guide/kernel-parameters.txt | 5 +++--
>> arch/arm64/mm/init.c | 3 ++-
>> 2 files changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index f6ff55840751a78..1b543c3109f4851 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -823,7 +823,7 @@
>> low memory is needed to make sure DMA buffers for 32-bit
>> devices won't run out. Kernel would try to allocate
>> at least 256M below 4G automatically.
>> - This one let user to specify own low range under 4G
>> + This one lets the user specify own low range under 4G
> ~ This one let users specify own low range ...
>
> Other than this nitpick, LGTM
This is Catalin's response a few days ago:
Slightly more correct is "This one lets the user specify..."
I didn't googled "This one lets", but I googled "It lets". I think he wrote it right.
Both "the user" and "users" seem to be right.
>
> Acked-by: Baoquan He <bhe@xxxxxxxxxx>
>
>> for second kernel instead.
>> 0: to disable low allocation.
>> It will be ignored when crashkernel=X,high is not used
>> @@ -832,7 +832,8 @@
>> [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.
>> + 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 18ba66c90991ea0..ac510fb6a2c0189 100644
>> --- a/arch/arm64/mm/init.c
>> +++ b/arch/arm64/mm/init.c
>> @@ -170,7 +170,8 @@ static void __init reserve_crashkernel(void)
>> return;
>> }
>>
>> - if (crash_low_size && reserve_crashkernel_low(crash_low_size)) {
>> + if ((crash_base >= CRASH_ADDR_LOW_MAX) &&
>> + crash_low_size && reserve_crashkernel_low(crash_low_size)) {
>> memblock_phys_free(crash_base, crash_size);
>> return;
>> }
>> --
>> 2.25.1
>>
>
> .
>
--
Regards,
Zhen Lei
