Re: [PATCH v5 2/2] selftests/resctrl: Recognise aarch64 as a vendor for L3_NONCONT_CAT

[Reinette Chatre]

Hi Ben,

On 10/20/26 9:18 AM, Ben Horgan wrote:
> On 12/10/2026 08:47, Richard Cheng wrote:

>> diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
>> index 0a417267dd74..f4b02b3eedd7 100644
>> --- a/tools/testing/selftests/resctrl/cat_test.c
>> +++ b/tools/testing/selftests/resctrl/cat_test.c
>> @@ -271,8 +271,13 @@ static bool arch_supports_noncont_cat(const struct resctrl_test *test)
>>  {
>>  	unsigned int vendor_id = get_vendor();
>>  
>> -	/* AMD and Hygon always support non-contiguous CBM. */
>> -	if (vendor_id == ARCH_AMD || vendor_id == ARCH_HYGON)
>> +	/*
>> +	 * AMD and Hygon always support non-contiguous CBM. ARM/MPAM defines
>> +	 * MPAMCFG_CPBM as a bitmap with no contiguity constraint per ARM
>> +	 * DDI 0598.
>> +	 */
>> +	if (vendor_id == ARCH_AMD || vendor_id == ARCH_HYGON ||
>> +	    vendor_id == ARCH_ARM)
>>  		return true;
> 
> Would it be better not to just to use the information resctrl advertises?
> /sys/fs/resctrl/info/L3/sparse_masks

The result of this architecture specific test is used to validate that 
/sys/fs/resctrl/info/L3/sparse_masks provides accurate information.

This test was originally developed on Intel where support for
sparse masks need to be discovered from the hardware. 

> 
> Is there any reason this test doesn't use that other than being written before its introduction?
Reinette