Re: [PATCH 1/1] x86/acpi: Use FADT flags to determine the PMTMR width

[Jan Beulich <jbeulich@xxxxxxxx>]

On 16.06.2020 16:59, Roger Pau Monné wrote:
> On Tue, Jun 16, 2020 at 03:25:42PM +0200, Jan Beulich wrote:
>> --- unstable.orig/xen/arch/x86/acpi/boot.c
>> +++ unstable/xen/arch/x86/acpi/boot.c
>> @@ -480,7 +480,9 @@ static int __init acpi_parse_fadt(struct
>>      if (fadt->header.revision >= FADT2_REVISION_ID) {
>>              /* FADT rev. 2 */
>>              if (fadt->xpm_timer_block.space_id ==
>> -                ACPI_ADR_SPACE_SYSTEM_IO) {
>> +                ACPI_ADR_SPACE_SYSTEM_IO &&
>> +                (fadt->xpm_timer_block.access_width == 0 ||
>> +                 fadt->xpm_timer_block.access_width == 3)) {
> 
> We should really have defines for those values, or else they seem to
> imply actual access sizes. What about adding
> ACPI_ADDR_ACCESS_{LEGACY,BYTE,WORD,DWORD,QWORD}?

If there were such defines, I'd have used them. Adding them is
inappropriate though, as this would modify an imported header in a
Xen-specific way. We could leverage ACPI_ACCESS_BIT_WIDTH() here,
though.

> Also the check for the access size seems kind of unrelated to the
> patch itself? (not that I'm opposed to it)

It's related, but could also live in its own patch.

Jan