Messages in this thread | | | Subject | Re: [PATCH v2 1/2] ACPI/PPTT: Add support for ACPI 6.3 thread flag | From | John Garry <> | Date | Wed, 19 Jun 2019 10:15:24 +0100 |
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On 18/06/2019 22:28, Jeremy Linton wrote: > Hi, > > On 6/18/19 12:23 PM, John Garry wrote: >> On 18/06/2019 15:40, Valentin Schneider wrote: >>> On 18/06/2019 15:21, Jeremy Linton wrote: >>> [...] >>>>>> + * Return: -ENOENT if the PPTT doesn't exist, the CPU cannot be >>>>>> found or >>>>>> + * the table revision isn't new enough. >>>>>> + * Otherwise returns flag value >>>>>> + */ >>>>> >>>>> Nit: strictly speaking we're not returning the flag value but its mask >>>>> applied to the flags field. I don't think anyone will care about >>>>> getting >>>>> the actual flag value, but it should be made obvious in the doc: >>>> >>>> Or I clarify the code to actually do what the comments says. Maybe >>>> that is what John G was also pointing out too? >>>> >> >> No, I was just saying that the kernel topology can be broken without >> this series. >> >>> >>> Mmm I didn't find any reply from John regarding this in v1, but I >>> wouldn't >>> mind either way, as long as the doc & code are aligned. >>> >> >> BTW, to me, function acpi_pptt_cpu_is_thread() seems to try to do too >> much, i.e. check if the PPTT is new enough to support the thread flag >> and also check if it is set for a specific cpu. I'd consider separate >> functions here. >
Hi,
> ? Your suggesting replacing the >
I am not saying definitely that this should be changed, it's just that acpi_pptt_cpu_is_thread() returning false, true, or "no entry" is not a typical API format.
How about acpi_pptt_support_thread_info(cpu) and acpi_pptt_cpu_is_threaded(cpu), both returning false/true only?
None of this is ideal.
BTW, Have you audited which arm64 systems have MT bit set legitimately?
> > if (table->revision >= rev)
I know that checking the table revision is not on the fast path, but it seems unnecessarily inefficient to always read it this way, I mean calling acpi_table_get().
Can you have a static value for the table revision? Or is this just how other table info is accessed in ACPI code?
> cpu_node = acpi_find_processor_node(table, acpi_cpu_id); > > check with > > if (revision_check(table, rev)) > cpu_node = acpi_find_processor_node(table, acpi_cpu_id); > > > and a function like > > static int revision_check(acpixxxx *table, int rev) > { > return (table->revision >= rev); > } > > Although, frankly if one were to do this, it should probably be a macro > with the table type, and used in the dozen or so other places I found > doing similar checks (spcr, iort, etc). > > Or something else? > > > >
thanks, John
>> >>> [...] >>> >>> . >>> >> >> > > > . >
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