Re: [Qemu-devel] [PATCH v3 01/50] trace: expand mem_info:size_shift to 3 bits

[Alex Bennée]

Richard Henderson <address@hidden> writes:

> On 6/14/19 10:11 AM, Alex Bennée wrote:
>> From: "Emilio G. Cota" <address@hidden>
>>
>> This will allow us to trace 16B-long memory accesses.
>>
>> Reviewed-by: Alex Bennée <address@hidden>
>> Signed-off-by: Emilio G. Cota <address@hidden>
>> ---
>>  trace-events | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/trace-events b/trace-events
>> index 844ee58dd9..037169aab3 100644
>> --- a/trace-events
>> +++ b/trace-events
>> @@ -159,7 +159,7 @@ vcpu guest_cpu_reset(void)
>>  # Access information can be parsed as:
>>  #
>>  # struct mem_info {
>> -#     uint8_t size_shift : 2; /* interpreted as "1 << size_shift" bytes */
>> +#     uint8_t size_shift : 3; /* interpreted as "1 << size_shift" bytes */
>>  #     bool    sign_extend: 1; /* sign-extended */
>>  #     uint8_t endianness : 1; /* 0: little, 1: big */
>>  #     bool    store      : 1; /* wheter it's a store operation */
>>
>
> Well, 128B-long memory accesses.  But SVE supports 256B memory accesses
> already.  So why not add one more bit now.

Good point.

Do we have any architectures that do load/stores that are not power of
2? I guess the SVE non-faulting accesses are treated as a series of elem
size accesses.

>
>
> r~


--
Alex Bennée