[PATCH] powerpc/powernv/memtrace: Fake non-memblock aligned sized traces

[Michael Ellerman]

Jordan Niethe <jniethe5 at gmail.com> writes:
> On Mon, Nov 16, 2020 at 11:02 PM Michael Ellerman <mpe at ellerman.id.au> wrote:
>>
>> Jordan Niethe <jniethe5 at gmail.com> writes:
>> > The hardware trace macros which use the memory provided by memtrace are
>> > able to use trace sizes as small as 16MB. Only memblock aligned values
>> > can be removed from each NUMA node by writing that value to
>> > memtrace/enable in debugfs.  This means setting up, say, a 16MB trace is
>> > not possible.  To allow such a trace size, instead align whatever value
>> > is written to memtrace/enable to the memblock size for the purpose of
>> > removing it from each NUMA node but report the written value from
>> > memtrace/enable and memtrace/x/size in debugfs.
>>
>> Why does it matter if the size that's removed is larger than the size
>> that was requested?
>>
>> Is it about constraining the size of the trace? If so that seems like it
>> should be the job of the tracing tools, not the kernel.
>
> Yeah about constraining the size, I'll just do it in the trace tools.

OK, I think that would be better. Thanks.

cheers