Messages in this thread |  | | | From | Robert Hancock <> | | Subject | Re: [PATCH] ACPI suspend: Blacklist boxes that require us to set SCI_EN directly on resume | | Date | Mon, 17 Nov 2008 23:45:59 -0600 | |
Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@sisk.pl>
> Subject: ACPI suspend: Blacklist boxes that require us to set SCI_EN directly on resume
>
> Some Apple boxes evidently require us to set SCI_EN on resume
> directly, because if we don't do that, they hung somewhere in the
> resume code path. Moreover, on these boxes it is not sufficient to
> use acpi_enable() to turn ACPI on during resume. All of this is
> against the ACPI specification which states that (1) the BIOS is
> supposed to return from the S3 sleep state with ACPI enabled
> (SCI_EN set) and (2) the SCI_EN bit is owned by the hardware and we
> are not supposed to change it.
>
> For this reason, blacklist the affected systems so that the SCI_EN
> bit is set during resume on them.
>
> [NOTE: Unconditional setting SCI_EN for all system on resume doesn't
> work, because it makes some other systems crash (that's to be
> expected). Also, it is not entirely clear right now if all of the
> Apple boxes require this workaround.]
This is rather gross. The usual question arises, why does Windows work
without such a hack? Maybe there is no better solution for now, but
somebody should really look into why the behavior is different in Linux..
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