Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [Xen-devel] [GIT PULL] xen: features and fixes for 4.8-rc0 | Date | Thu, 28 Jul 2016 01:09:06 +0200 |
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On Wednesday, July 27, 2016 07:57:34 PM Andrew Cooper wrote: > On 27/07/16 19:42, Linus Torvalds wrote: > > On Wed, Jul 27, 2016 at 6:45 AM, David Vrabel <dvrabel@cantab.net> wrote: > >> Shannon Zhao (16): > >> Xen: ACPI: Hide UART used by Xen > > So this caused a trivial conflict. No biggie, it wasn't bad and the > > patch was acked by Rafael. However, looking at it made me somewhat > > unhappy. > > > > Should the device entry in ACPI really be hidden unconditionally? In > > particular, if we are *not* running under virtualization, it sounds > > wrong to hide it. > > > > Comments? Am I missing something? > > The purpose of the ACPI STAO table (Status Override table, ratified in > ACPI 6.0) is to list items elsewhere in the ACPI namespace which should > be completely ignored. It is used in cases where it is impossible or > prohibitive to edit the system AML. > > The patch itself only hides the UART if instructed to do so by the STAO > table (last hunk).
Right.
The STAO definition document:
http://wiki.xenproject.org/mediawiki/images/0/02/Status-override-table.pdf
requires as to "operate as if that device does not exist", quite literally.
Thanks, Rafael
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