[PATCH] ACPI suspend: Always use the 32-bit waking vector

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Friday, 5 of September 2008, Li, Shaohua wrote:
> 
> >-----Original Message-----
> >From: linux-acpi-owner@vger.kernel.org [mailto:linux-acpi-
> >owner@vger.kernel.org] On Behalf Of Zhao Yakui
> >Sent: Friday, September 05, 2008 9:17 AM
> >To: Matthew Garrett
> >Cc: Rafael J. Wysocki; Zhang, Rui; lenb@kernel.org; linux-
> >acpi@vger.kernel.org; andi@firstfloor.org
> >Subject: Re: [PATCH]: ACPI : Set 32bit and 64bit waking vector in FCAS
> >table
> >
> >On Thu, 2008-09-04 at 13:07 +0100, Matthew Garrett wrote:
> >> On Thu, Sep 04, 2008 at 11:37:51AM +0200, Rafael J. Wysocki wrote:
> >> > > so it seems that the BIOS sets facs->xfirmware_waking_vector during
> >> > > POST, but uses facs->firmware_waking_vector to get back during resume.
> >> >
> >> > So the BIOS is buggy, so let's add a quirk for it.
> >>
> >> Does the machine resume in Windows? If so, do we have any evidence that
> >> Windows has a quirks list to handle this case? If not, then I suspect
> >> that Windows sets both and this is what everyone has tested against.
> >The laptop can be resumed on windows.(XP & Vista). And we don't know
> >whether there exists the quirk list to handler this case on windows.
> >Maybe what you said is right.
> >In fact it is harmless when both 32bit and 64bit waking vector in FACS
> >table are set. When the system is resumed, BIOS will transfer control to
> >the predefined waking vector. As we set the same waking vector, either
> >of them is OK.
> >
> >There exists the difference between 32bit and 64bit waking vector unless
> >the waking address is above 4GB. But in fact the waking address is below
> >1MB on most machines as the waking address needs to be accessed by BIOS.
> >
> >So in most cases the 32bit and 64bit waking vector are the same value.
> >BIOS can transfer control to either of them.
> There was discussion about this issue several months ago (intel's ml), looks
> people forgot to take action after the discussion. The spec owner said 64bit
> vector is used in protected mode. That is if OS sets it, wakeup code is
> called in protected mode by BIOS. So the 64-bit vector shouldn't be used.   

Well, I read this part of the spec (2.0c, 3.0b) more carefully and it matches
what you're saying.  Moreover, my understanding of it is that we should
actually _clear_ the 64-bit vector on systems that support it, because
otherwise the BIOS is supposed to use it and call the wake-up code in protected
mode.

The appended patch is based on this observation.

Thanks,
Rafael

---
From: Rafael J. Wysocki <rjw@sisk.pl>

ACPI suspend: Always use the 32-bit waking vector

According to the ACPI specification 2.0c and later, the 64-bit waking vector
should be cleared and the 32-bit waking vector should be used, unless we want
the wake-up code to be called by the BIOS in Protected Mode.  Moreover, some
systems (for example HP dv5-1004nr) are known to fail to resume if the 64-bit
waking vector is used.  Therefore, modify the code to clear the 64-bit waking
vector, for FACS version 1 or greater, and set the 32-bit one before suspend.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 drivers/acpi/hardware/hwsleep.c |   37 +++++++++++--------------------------
 1 file changed, 11 insertions(+), 26 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
@@ -78,19 +78,17 @@ acpi_set_firmware_waking_vector(acpi_phy
 		return_ACPI_STATUS(status);
 	}
 
-	/* Set the vector */
+	/*
+	 * According to the ACPI specification 2.0c and later, the 64-bit
+	 * waking vector should be cleared and the 32-bit waking vector should
+	 * be used, unless we want the wake-up code to be called by the BIOS in
+	 * Protected Mode.  Some systems (for example HP dv5-1004nr) are known
+	 * to fail to resume if the 64-bit vector is used.
+	 */
+	if (facs->version >= 1)
+		facs->xfirmware_waking_vector = 0;
 
-	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 {
-		/*
-		 * ACPI 2.0 FACS with valid X_ field
-		 */
-		facs->xfirmware_waking_vector = physical_address;
-	}
+	facs->firmware_waking_vector = (u32)physical_address;
 
 	return_ACPI_STATUS(AE_OK);
 }
@@ -134,20 +132,7 @@ acpi_get_firmware_waking_vector(acpi_phy
 	}
 
 	/* Get the vector */
-
-	if ((facs->length < 32) || (!(facs->xfirmware_waking_vector))) {
-		/*
-		 * ACPI 1.0 FACS or short table or optional X_ field is zero
-		 */
-		*physical_address =
-		    (acpi_physical_address) facs->firmware_waking_vector;
-	} else {
-		/*
-		 * ACPI 2.0 FACS with valid X_ field
-		 */
-		*physical_address =
-		    (acpi_physical_address) facs->xfirmware_waking_vector;
-	}
+	*physical_address = (acpi_physical_address)facs->firmware_waking_vector;
 
 	return_ACPI_STATUS(AE_OK);
 }
--
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