PROBLEM: ACPI freezes 2.6.1 on boot

PROBLEM: ACPI freezes 2.6.1 on boot

[Georg C. F. Greve]

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Hi all,

I've seen the mail by Martin Loschwitz of January 1st 2004, in which
he reported:

 > I'm writing this mail as I'm discovering ACPI related problems on
 > my Acer TravelMate 800LCi notebook with Linux 2.6.1-rc1-mm1.

 > While the system boots up fine with Linux 2.6.1-rc1, with
 > 2.6.1-rc1-mm1 it hangs while booting. The last message printed to
 > screen is "ACPI: IRQ 9 was Edge Triggered, setting to Level
 > Triggerd". This is fully reproducable with a Linux 2.6.0 kernel
 > which has the ACPI20031203 patch applied.

I'm now seeing the _exact same problem_ on an ASUS M2400N [*] with a
Linux 2.6.1 (unpatched) kernel. The kernel freezes after printing 

 "ACPI: IRQ 9 was Edge Triggered, setting to Level Triggerd" 

(yes, the typo is in the kernel, it seems)

I've seen no reply to his mail. Has the problem been solved or is it
still a known bug(tm)?

Martin? Were you successful in resolving that problem?

Regards,
Georg


[*] Pentium 4 M Centrino, 1.6, 512MB, Intel 855GM chipset

-- 
Georg C. F. Greve                                       <greve@gnu.org>
Free Software Foundation Europe	                 (http://fsfeurope.org)
Brave GNU World	                           (http://brave-gnu-world.org)

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Re: PROBLEM: ACPI freezes 2.6.1 on boot

[Martin Loschwitz]

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On Wed, Jan 21, 2004 at 12:12:05PM +0100, Georg C. F. Greve wrote:
> Hi all,
> 
> I've seen the mail by Martin Loschwitz of January 1st 2004, in which
> he reported:
> 
>  > I'm writing this mail as I'm discovering ACPI related problems on
>  > my Acer TravelMate 800LCi notebook with Linux 2.6.1-rc1-mm1.
> 
>  > While the system boots up fine with Linux 2.6.1-rc1, with
>  > 2.6.1-rc1-mm1 it hangs while booting. The last message printed to
>  > screen is "ACPI: IRQ 9 was Edge Triggered, setting to Level
>  > Triggerd". This is fully reproducable with a Linux 2.6.0 kernel
>  > which has the ACPI20031203 patch applied.
> 
> I'm now seeing the _exact same problem_ on an ASUS M2400N [*] with a
> Linux 2.6.1 (unpatched) kernel. The kernel freezes after printing 
> 
>  "ACPI: IRQ 9 was Edge Triggered, setting to Level Triggerd" 
> 
> (yes, the typo is in the kernel, it seems)
> 
> I've seen no reply to his mail. Has the problem been solved or is it
> still a known bug(tm)?
> 
> Martin? Were you successful in resolving that problem?
> 
By now means. I, however, didn't even try to get a solution since back
then. Since the bug appeared with a patched 2.6.0 and 2.6.1-mm2, which
was one of the first patches including the new ACPI, it was clear to
me that it was ACPI related and that I would better wait for somebody
to find the root of the evil and to kill it.

I see your "Notebook vs. Linux"-story continues to be unsuccessfull,
though :(

> Regards,
> Georg
> 
> 
> [*] Pentium 4 M Centrino, 1.6, 512MB, Intel 855GM chipset
> 
> -- 
> Georg C. F. Greve                                       <greve@gnu.org>
> Free Software Foundation Europe	                 (http://fsfeurope.org)
> Brave GNU World	                           (http://brave-gnu-world.org)


-- 
  .''`.   Martin Loschwitz           Debian GNU/Linux developer
 : :'  :  madkiss@madkiss.org        madkiss@debian.org
 `. `'`   http://www.madkiss.org/    people.debian.org/~madkiss/
   `-     Use Debian GNU/Linux 3.0!  See http://www.debian.org/

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Re: PROBLEM: ACPI freezes 2.6.1 on boot

[Georg C. F. Greve]

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 || On Wed, 21 Jan 2004 16:35:51 +0100
 || Martin Loschwitz <madkiss@madkiss.org> wrote: 

 ml> By now means. I, however, didn't even try to get a solution since
 ml> back then. Since the bug appeared with a patched 2.6.0 and
 ml> 2.6.1-mm2, which was one of the first patches including the new
 ml> ACPI, it was clear to me that it was ACPI related and that I
 ml> would better wait for somebody to find the root of the evil and
 ml> to kill it.

Damn. ACPI being somewhat a central issue, I hoped someone had picked
it up already. Did you write to the ACPI list about it? My mail
apparently didn't make it (couldn't see it in the archive).


 ml> I see your "Notebook vs. Linux"-story continues to be
 ml> unsuccessfull, though :(

Yup, it seems that way. It is an eternal struggle. *sigh*

Nice to see that someone read the issue, though. :)

Regards,
Georg

-- 
Georg C. F. Greve                                       <greve@gnu.org>
Free Software Foundation Europe	                 (http://fsfeurope.org)
Brave GNU World	                           (http://brave-gnu-world.org)

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RE: PROBLEM: ACPI freezes 2.6.1 on boot

[Nakajima, Jun]

Right now I forwarded this to linux-acpi@intel.com, but copying the ACPI
mailing list acpi-devel@lists.sourceforge.net would be helpful in
general. Len can provide more specific directions for reporting ACPI
bugs.

Thanks,
Jun
> -----Original Message-----
> From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-
> owner@vger.kernel.org] On Behalf Of Georg C. F. Greve
> Sent: Wednesday, January 21, 2004 8:12 AM
> To: Martin Loschwitz
> Cc: linux-kernel@vger.kernel.org
> Subject: Re: PROBLEM: ACPI freezes 2.6.1 on boot
> 
>  || On Wed, 21 Jan 2004 16:35:51 +0100
>  || Martin Loschwitz <madkiss@madkiss.org> wrote:
> 
>  ml> By now means. I, however, didn't even try to get a solution since
>  ml> back then. Since the bug appeared with a patched 2.6.0 and
>  ml> 2.6.1-mm2, which was one of the first patches including the new
>  ml> ACPI, it was clear to me that it was ACPI related and that I
>  ml> would better wait for somebody to find the root of the evil and
>  ml> to kill it.
> 
> Damn. ACPI being somewhat a central issue, I hoped someone had picked
> it up already. Did you write to the ACPI list about it? My mail
> apparently didn't make it (couldn't see it in the archive).
> 
> 
>  ml> I see your "Notebook vs. Linux"-story continues to be
>  ml> unsuccessfull, though :(
> 
> Yup, it seems that way. It is an eternal struggle. *sigh*
> 
> Nice to see that someone read the issue, though. :)
> 
> Regards,
> Georg
> 
> --
> Georg C. F. Greve
<greve@gnu.org>
> Free Software Foundation Europe
> (http://fsfeurope.org)
> Brave GNU World
(http://brave-gnu-world.org)

Re: PROBLEM: ACPI freezes 2.6.1 on boot

[Linus Torvalds]

On Wed, 21 Jan 2004, Georg C. F. Greve wrote:
> 
> I'm now seeing the _exact same problem_ on an ASUS M2400N [*] with a
> Linux 2.6.1 (unpatched) kernel. The kernel freezes after printing 
> 
>  "ACPI: IRQ 9 was Edge Triggered, setting to Level Triggerd" 

Does it go away if you just make "acpi_pic_set_level_irq()" do nothing (ie 
just remove the "outb()" call

	arch/i386/kernel/acpi/boot.c line 273

or just make the if-statement be always false).

It's entirely possible that the SCI is just horribly broken, and can't be 
level-triggered.

Btw, usually a good idea to at least cc the developer list for the 
particular subsystem. In this case <acpi-devel@lists.sourceforge.net>. 
Many people don't have the time to follow linux-kernel.

		Linus

Re: PROBLEM: ACPI freezes 2.6.1 on boot

[Georg C. F. Greve]

|| On 2004-01-21 18:56:59, Linus Torvalds wrote:

 > Does it go away if you just make "acpi_pic_set_level_irq()" do
 > nothing (ie just remove the "outb()" call
 > 
 > 	arch/i386/kernel/acpi/boot.c line 273
 > 
 > or just make the if-statement be always false).

 > It's entirely possible that the SCI is just horribly broken, and
 > can't be level-triggered.

Just tried removing the outb() call both from plain vanilla 2.6.1 and
one with the latest ACPI patch. No change. The system freezes with the
same message at the same point during bootup.

Any other ideas?

Regards,
Georg

-- 
Georg C. F. Greve                                       <greve@gnu.org>
Free Software Foundation Europe	                 (http://fsfeurope.org)
Brave GNU World	                           (http://brave-gnu-world.org)

Re: PROBLEM: ACPI freezes 2.6.1 on boot

[Georg C. F. Greve]

 || On Wed, 21 Jan 2004 08:32:50 -0800
 || "Nakajima, Jun" <jun.nakajima@intel.com> wrote: 

 nj> Right now I forwarded this to linux-acpi@intel.com, but copying
 nj> the ACPI mailing list acpi-devel@lists.sourceforge.net would be
 nj> helpful in general. Len can provide more specific directions for
 nj> reporting ACPI bugs.

Thanks.

FYI, there is a bug on the Linux kernel bugzilla corresponding to this
problem: 

         http://bugzilla.kernel.org/show_bug.cgi?id=1774

Regards,
Georg

-- 
Georg C. F. Greve                                       <greve@gnu.org>
Free Software Foundation Europe	                 (http://fsfeurope.org)
Brave GNU World	                           (http://brave-gnu-world.org)

RE: PROBLEM: ACPI freezes 2.6.1 on boot

[Brown, Len]

Didn't see that report b/c it was filed against "Alternate Trees".  I've
updated it to be against "ACPI" and assigned it to myself -- lets work
it there.

Thanks,
-Len

> -----Original Message-----
> From: Georg C. F. Greve [mailto:greve@gnuhh.org] On Behalf Of 
> Georg C. F. Greve
> Sent: Wednesday, January 21, 2004 4:22 PM
> To: Nakajima, Jun
> Cc: Martin Loschwitz; linux-kernel@vger.kernel.org; Brown, 
> Len; acpi-devel@lists.sourceforge.net
> Subject: Re: PROBLEM: ACPI freezes 2.6.1 on boot
> 
> 
>  || On Wed, 21 Jan 2004 08:32:50 -0800
>  || "Nakajima, Jun" <jun.nakajima@intel.com> wrote: 
> 
>  nj> Right now I forwarded this to linux-acpi@intel.com, but copying
>  nj> the ACPI mailing list acpi-devel@lists.sourceforge.net would be
>  nj> helpful in general. Len can provide more specific directions for
>  nj> reporting ACPI bugs.
> 
> Thanks.
> 
> FYI, there is a bug on the Linux kernel bugzilla corresponding to this
> problem: 
> 
         http://bugzilla.kernel.org/show_bug.cgi?id=1774

Regards,
Georg

-- 
Georg C. F. Greve                                       <greve@gnu.org>
Free Software Foundation Europe	                 (http://fsfeurope.org)
Brave GNU World	                           (http://brave-gnu-world.org)

Re: PROBLEM: ACPI freezes 2.6.1 on boot

[Linus Torvalds]

On Wed, 21 Jan 2004, Georg C. F. Greve wrote:
> 
> Just tried removing the outb() call both from plain vanilla 2.6.1 and
> one with the latest ACPI patch. No change. The system freezes with the
> same message at the same point during bootup.
> 
> Any other ideas?

Nope. It would probably help to enable ACPI debugging, and see if there 
are any other messages printed.

And it would also help to go back to the working kernel (somebody said 
2.6.1-rc1 worked), and try to see what the differences are and what is the 
first kernel that breaks. -rc2? -rc3? or 2.6.1-final?

		Linus

Re: PROBLEM: ACPI freezes 2.6.1 on boot

[Georg C. F. Greve]

UPDATE:

Out of curiosity and because it seemed to be the interrupt handling
that was problematic, I disabled "Local APIC support on uniprocessors."

That convinced the machine to boot with ACPI.

Here is an excerpt from dmesg regarding ACPI only:

[...]
ACPI: RSDP (v000 ACPIAM                                    ) @ 0x000f4b60
ACPI: RSDT (v001 A M I  OEMRSDT  0x06000310 MSFT 0x00000097) @ 0x1f740000
ACPI: FADT (v002 A M I  OEMFACP  0x06000310 MSFT 0x00000097) @ 0x1f740200
ACPI: OEMB (v001 A M I  OEMBIOS  0x06000310 MSFT 0x00000097) @ 0x1f750040
ACPI: DSDT (v001  0ABBD 0ABBD001 0x00000001 MSFT 0x0100000d) @ 0x00000000
[...]
ACPI: Subsystem revision 20031002
ACPI: IRQ 9 was Edge Triggered, setting to Level Triggerd
ACPI: Interpreter enabled
ACPI: Using PIC for interrupt routing
ACPI: PCI Root Bridge [PCI0] (00:00)
[...]
ACPI: PCI Interrupt Routing Table [\_SB_.PCI0._PRT]
ACPI: PCI Interrupt Routing Table [\_SB_.PCI0.P0P1._PRT]
ACPI: Embedded Controller [EC0] (gpe 28)
ACPI: PCI Interrupt Link [LNKA] (IRQs 3 4 *5 6 7 11 12)
ACPI: PCI Interrupt Link [LNKB] (IRQs 3 4 5 6 7 12)
ACPI: PCI Interrupt Link [LNKC] (IRQs 3 4 *5 6 7 12)
ACPI: PCI Interrupt Link [LNKD] (IRQs 3 4 *5 6 7 12)
ACPI: PCI Interrupt Link [LNKE] (IRQs 3 4 5 6 7 12)
ACPI: PCI Interrupt Link [LNKF] (IRQs 3 4 5 6 7 12)
ACPI: PCI Interrupt Link [LNKG] (IRQs 3 4 5 6 7 12)
ACPI: PCI Interrupt Link [LNKH] (IRQs 3 *4 5 6 7 12)
ACPI: Power Resource [GFAN] (off)
[...]
ACPI: PCI Interrupt Link [LNKA] enabled at IRQ 5
ACPI: PCI Interrupt Link [LNKD] enabled at IRQ 5
ACPI: PCI Interrupt Link [LNKC] enabled at IRQ 5
ACPI: PCI Interrupt Link [LNKH] enabled at IRQ 4
ACPI: PCI Interrupt Link [LNKB] enabled at IRQ 5
PCI: Using ACPI for IRQ routing
PCI: if you experience problems, try using option 'pci=noacpi' or even 'acpi=off'
[...]
speedstep-centrino: found "Intel(R) Pentium(R) M processor 1600MHz": max frequency: 1600000kHz
[...]
ACPI: AC Adapter [AC0] (on-line)
ACPI: Battery Slot [BAT0] (battery present)
ACPI: Power Button (FF) [PWRF]
ACPI: Sleep Button (CM) [SLPB]
ACPI: Lid Switch [LID]
ACPI: Fan [FN00] (off)
ACPI: Processor [CPU1] (supports C1 C2 C3, 8 throttling states)
ACPI: Thermal Zone [THRM] (54 C)
Asus Laptop ACPI Extras version 0.26
  M2N model detected, supported
[...]
Resume Machine: resuming from /dev/hda8
Resuming from device hda8
Resume Machine: This is normal swap space
PM: Reading pmdisk image.
PM: Resume from disk failed.
ACPI: (supports S0 S1 S3 S4 S5)
[...]


This looks pretty good, I think. Already checked some
funcionality. Suspend to RAM seems to work, although the display
remains dark on restart (but normal shutdown works, so the machine is
definitely back up).

So the problem we've been seeing seems to be related to the
interaction between local APIC support and ACPI.

I hope this helps tracking it down...

Regards,
Georg


P.S. Martin? Can you reproduce this?

-- 
Georg C. F. Greve                                       <greve@gnu.org>
Free Software Foundation Europe	                 (http://fsfeurope.org)
Brave GNU World	                           (http://brave-gnu-world.org)

Re: [ACPI] Re: PROBLEM: ACPI freezes 2.6.1 on boot

[Karol Kozimor]

Thus wrote Georg C. F. Greve:
> So the problem we've been seeing seems to be related to the
> interaction between local APIC support and ACPI.

We've definitely had those problems before (with ASUS L3800C), there's 
even a patch fixing this issue (attached below) you might try.
I guess that's another of those lost and forgotten bugzilla bugs :)

-- 
Karol 'sziwan' Kozimor
sziwan@hell.org.pl


diff -Bru linux-2.6.0-test8/arch/i386/kernel/apic.c patched/arch/i386/kernel/apic.c
--- linux-2.6.0-test8/arch/i386/kernel/apic.c	2003-10-18 05:43:36.000000000 +0800
+++ patched/arch/i386/kernel/apic.c	2003-10-30 23:17:50.000000000 +0800
@@ -836,8 +836,8 @@
 {
 	unsigned int lvtt1_value, tmp_value;
 
-	lvtt1_value = SET_APIC_TIMER_BASE(APIC_TIMER_BASE_DIV) |
-			APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR;
+	lvtt1_value = APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR;
+
 	apic_write_around(APIC_LVTT, lvtt1_value);
 
 	/*
diff -Bru linux-2.6.0-test8/drivers/acpi/bus.c patched/drivers/acpi/bus.c
--- linux-2.6.0-test8/drivers/acpi/bus.c	2003-10-18 05:43:19.000000000 +0800
+++ patched/drivers/acpi/bus.c	2003-10-30 23:20:32.000000000 +0800
@@ -589,6 +589,7 @@
 
 	ACPI_FUNCTION_TRACE("acpi_bus_init");
 
+	disable_APIC_timer();
 	status = acpi_initialize_subsystem();
 	if (ACPI_FAILURE(status)) {
 		printk(KERN_ERR PREFIX "Unable to initialize the ACPI Interpreter\n");
@@ -643,6 +644,7 @@
 		goto error1;
 	}
 
+	enable_APIC_timer();
 	printk(KERN_INFO PREFIX "Interpreter enabled\n");
 
 	/*
@@ -672,6 +674,7 @@
 error1:
 	acpi_terminate();
 error0:
+	enable_APIC_timer();
 	return_VALUE(-ENODEV);
 }
 

Re: [ACPI] Re: PROBLEM: ACPI freezes 2.6.1 on boot

[Mikael Pettersson]

Karol Kozimor writes:
 > Thus wrote Georg C. F. Greve:
 > > So the problem we've been seeing seems to be related to the
 > > interaction between local APIC support and ACPI.
 > 
 > We've definitely had those problems before (with ASUS L3800C), there's 
 > even a patch fixing this issue (attached below) you might try.
 > I guess that's another of those lost and forgotten bugzilla bugs :)
 > 
 > -- 
 > Karol 'sziwan' Kozimor
 > sziwan@hell.org.pl
 > 
 > 
 > diff -Bru linux-2.6.0-test8/arch/i386/kernel/apic.c patched/arch/i386/kernel/apic.c
 > --- linux-2.6.0-test8/arch/i386/kernel/apic.c	2003-10-18 05:43:36.000000000 +0800
 > +++ patched/arch/i386/kernel/apic.c	2003-10-30 23:17:50.000000000 +0800
 > @@ -836,8 +836,8 @@
 >  {
 >  	unsigned int lvtt1_value, tmp_value;
 >  
 > -	lvtt1_value = SET_APIC_TIMER_BASE(APIC_TIMER_BASE_DIV) |
 > -			APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR;
 > +	lvtt1_value = APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR;
 > +
 >  	apic_write_around(APIC_LVTT, lvtt1_value);

What is the purpose of this change?
I don't remember seeing this before on LKML. (I don't have time to read bugzilla.)

Re: [ACPI] Re: PROBLEM: ACPI freezes 2.6.1 on boot

[Karol Kozimor]

Thus wrote Mikael Pettersson:
>  > diff -Bru linux-2.6.0-test8/arch/i386/kernel/apic.c patched/arch/i386/kernel/apic.c
>  > --- linux-2.6.0-test8/arch/i386/kernel/apic.c	2003-10-18 05:43:36.000000000 +0800
>  > +++ patched/arch/i386/kernel/apic.c	2003-10-30 23:17:50.000000000 +0800
>  > @@ -836,8 +836,8 @@
>  >  {
>  >  	unsigned int lvtt1_value, tmp_value;
>  >  
>  > -	lvtt1_value = SET_APIC_TIMER_BASE(APIC_TIMER_BASE_DIV) |
>  > -			APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR;
>  > +	lvtt1_value = APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR;
>  > +
>  >  	apic_write_around(APIC_LVTT, lvtt1_value);
> 
> What is the purpose of this change?
> I don't remember seeing this before on LKML. (I don't have time to read bugzilla.)

I don't really know. I'm not the author of the patch, I just found it on my
disk and I remember it allowed me to boot with LAPIC compiled in, as the
system would otherwise hang during _STA and _INI execution. I don't even
know if the patch is still correct.
Best regards,

-- 
Karol 'sziwan' Kozimor
sziwan@hell.org.pl

Re: [ACPI] Re: PROBLEM: ACPI freezes 2.6.1 on boot

[Georg C. F. Greve]

 || On Thu, 22 Jan 2004 13:08:54 +0100
 || Karol Kozimor <sziwan@hell.org.pl> wrote: 

 >> So the problem we've been seeing seems to be related to the
 >> interaction between local APIC support and ACPI.

 kk> We've definitely had those problems before (with ASUS L3800C),
 kk> there's even a patch fixing this issue (attached below) you might
 kk> try.  I guess that's another of those lost and forgotten bugzilla
 kk> bugs :)

Thanks a lot -- this patch fixed the problem for me.

The kernel now found the APIC and initialized ACPI (including
switching to level trigger) with no problems.

Could we please make sure this doesn't get lost again and makes it
into the kernel?

Regards,
Georg

-- 
Georg C. F. Greve                                       <greve@gnu.org>
Free Software Foundation Europe	                 (http://fsfeurope.org)
Brave GNU World	                           (http://brave-gnu-world.org)

Re: [ACPI] Re: PROBLEM: ACPI freezes 2.6.1 on boot

[Georg C. F. Greve]

 || On Thu, 22 Jan 2004 15:08:56 +0100
 || "Georg C. F. Greve" <greve@gnu.org> wrote: 

 gg> Could we please make sure this doesn't get lost again and makes
 gg> it into the kernel?

By the way, it seems that 

 http://bugzilla.kernel.org/show_bug.cgi?id=1774
 http://bugzilla.kernel.org/show_bug.cgi?id=1677
 http://bugzilla.kernel.org/show_bug.cgi?id=1530
 http://bugzilla.kernel.org/show_bug.cgi?id=1171

are probably related. So this could get rid of four bugzilla entries
at once. :)

Regards,
Georg

-- 
Georg C. F. Greve                                       <greve@gnu.org>
Free Software Foundation Europe	                 (http://fsfeurope.org)
Brave GNU World	                           (http://brave-gnu-world.org)

Re: [ACPI] Re: PROBLEM: ACPI freezes 2.6.1 on boot

[Linus Torvalds]

On Thu, 22 Jan 2004, Mikael Pettersson wrote:

> Karol Kozimor writes:
>  > 
>  > diff -Bru linux-2.6.0-test8/arch/i386/kernel/apic.c patched/arch/i386/kernel/apic.c
>  > --- linux-2.6.0-test8/arch/i386/kernel/apic.c	2003-10-18 05:43:36.000000000 +0800
>  > +++ patched/arch/i386/kernel/apic.c	2003-10-30 23:17:50.000000000 +0800
>  > @@ -836,8 +836,8 @@
>  >  {
>  >  	unsigned int lvtt1_value, tmp_value;
>  >  
>  > -	lvtt1_value = SET_APIC_TIMER_BASE(APIC_TIMER_BASE_DIV) |
>  > -			APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR;
>  > +	lvtt1_value = APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR;
>  > +
>  >  	apic_write_around(APIC_LVTT, lvtt1_value);
> 
> What is the purpose of this change?
> I don't remember seeing this before on LKML. (I don't have time to read bugzilla.)

Hmm.. It does seem to fix things for a couple of people, so it looks 
interesting.

As far as I can tell, the _only_ thing it does is to change the timer base
from "DIV" to "CLKIN". I seem to have misplaced my ia-32 "volume 3" thing, 
but I have an old one for a pentium, and that one doesn't actually
haev the timer-base thing at all - and marks those bits as "reserved".

So it is entirely possible that the only safe value to write there is 0.

Also, why the heck do we call that "lvtt1"? It's just lvtt - no "1" there
anywhere.

So I'm inclined to apply the patch, but it would be better if somebody who 
had more recent docs could tell me what those newer docs say is the 
difference bewteen BASE_CLKIN (0) and BASE_DIV (2)...

		Linus

Re: [ACPI] Re: PROBLEM: ACPI freezes 2.6.1 on boot

[Mikael Pettersson]

Linus Torvalds writes:
 > 
 > 
 > On Thu, 22 Jan 2004, Mikael Pettersson wrote:
 > 
 > > Karol Kozimor writes:
 > >  > 
 > >  > diff -Bru linux-2.6.0-test8/arch/i386/kernel/apic.c patched/arch/i386/kernel/apic.c
 > >  > --- linux-2.6.0-test8/arch/i386/kernel/apic.c	2003-10-18 05:43:36.000000000 +0800
 > >  > +++ patched/arch/i386/kernel/apic.c	2003-10-30 23:17:50.000000000 +0800
 > >  > @@ -836,8 +836,8 @@
 > >  >  {
 > >  >  	unsigned int lvtt1_value, tmp_value;
 > >  >  
 > >  > -	lvtt1_value = SET_APIC_TIMER_BASE(APIC_TIMER_BASE_DIV) |
 > >  > -			APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR;
 > >  > +	lvtt1_value = APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR;
 > >  > +
 > >  >  	apic_write_around(APIC_LVTT, lvtt1_value);
 > > 
 > > What is the purpose of this change?
 > > I don't remember seeing this before on LKML. (I don't have time to read bugzilla.)
 > 
 > Hmm.. It does seem to fix things for a couple of people, so it looks 
 > interesting.
 > 
 > As far as I can tell, the _only_ thing it does is to change the timer base
 > from "DIV" to "CLKIN". I seem to have misplaced my ia-32 "volume 3" thing, 
 > but I have an old one for a pentium, and that one doesn't actually
 > haev the timer-base thing at all - and marks those bits as "reserved".
 > 
 > So it is entirely possible that the only safe value to write there is 0.

Confirmed. Those bits (18 and 19 in LVTT) are marked reserved in the
latest IA32 Volume 3. I have no idea where this APIC_TIMER_BASE came
from (maybe some ancient discrete LAPIC thing?), but we almost certainly
shouldn't write anything but zero to them.

 > So I'm inclined to apply the patch, but it would be better if somebody who 

I agree. The patch should be applied.

/Mikael