Re: [PATCH]: ACPI : Set 32bit and 64bit waking vector in FCAS table

Zhang Rui
2008-09-04T09:19:33Z

On Thu, 2008-09-04 at 10:10 +0200, Rafael J. Wysocki wrote:
> On Thursday, 4 of September 2008, Zhao Yakui wrote:
> > Subject: ACPI : Set 32bit and 64bit waking vector in FCAS table
> > From: Zhao Yakui <yakui.zhao@intel.com>
> >
> > On some laptops only the 64bit waking vecotr is set for ACPI 2.0 FACS.
> > But when the system is resumed, BIOS will transfer control directly to
> > 32bit waking vector. In such case the system can't be resumed correctly.
> > Maybe it will be more appropriate that both the 32bit and 64bit waking
> > vector will be set for the ACPI 2.0 FACS when the system enters the S3
> > sleeping state.
> >
> > http://bugzilla.kernel.org/show_bug.cgi?id=11368
>
> Well, the spec (2.0c) says we should use facs->firmware_waking_vector only
> if facs->xfirmware_waking_vector is zero, so I'm afraid this change may cause
> regressions to happen.
>
> Moreover, both 1.0b and 2.0c say that facs->length should be at least 64 bytes,
> so the (facs->length >= 32) check is actually redundant (unless there is a
> quirk setting this value below 32 for some broken systems I'm not aware of).
>
> So, the question is what happens if we ignore the facs->length check on systems
> this patch is supposed to fix.
this should have no impact.
facs->length is also 64 bytes.
without the patch, xfirmware_waking_vector is set.
with this patch applied, both xfirmware and firmware_waking_vector are
set.
so it seems that the BIOS sets ﻿facs->xfirmware_waking_vector during
POST, but uses ﻿﻿facs->firmware_waking_vector to get back during resume.

thanks,
rui

> If they _still_ require
> facs->firmware_waking_vector to be set even if
> facs->xfirmware_waking_vector is non-zero, I'd prefer to add quirks for them
> instead of affecting everybody else.
>
> > Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
> > Signed-off-by: Zhang Rui <rui.zhang@intel.com>
> > ---
> > drivers/acpi/hardware/hwsleep.c | 14 +++++++-------
> > 1 file changed, 7 insertions(+), 7 deletions(-)
> >
> > Index: linux-2.6/drivers/acpi/hardware/hwsleep.c
> > ===================================================================
> > --- linux-2.6.orig/drivers/acpi/hardware/hwsleep.c
> > +++ linux-2.6/drivers/acpi/hardware/hwsleep.c
> > @@ -80,14 +80,14 @@ acpi_set_firmware_waking_vector(acpi_phy
> >
> > /* Set the vector */
> >
> > - if ((facs->length < 32) || (!(facs->xfirmware_waking_vector))) {
> > - /*
> > - * ACPI 1.0 FACS or short table or optional X_ field is zero
> > - */
> > - facs->firmware_waking_vector = (u32) physical_address;
> > - } else {
> > + /* 32 Bit wakeing vector is always set */
> > + facs->firmware_waking_vector = (u32) physical_address;
> > +
> > + if (facs->length >= 32) {
> > /*
> > - * ACPI 2.0 FACS with valid X_ field
> > + * ACPI 2.0 FACS with the valid X_filed. Its length
> > + * will be more than 32 bytes. In such case the 64 bit
> > + * waking vector is also set.
> > */
> > facs->xfirmware_waking_vector = physical_address;
> > }
> >
> >
> > --
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> >
>
>
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