[PATCH 3/14] kexec: apic-virtwire-on-shutdown.i386.patch

[PATCH 3/14] kexec: apic-virtwire-on-shutdown.i386.patch

[Eric W. Biederman]

Restore the local apic to virtual wire mode on reboot.

diff -uNr linux-2.6.8.1-mm2-i8259-sysfs.x86_64/arch/i386/kernel/apic.c linux-2.6.8.1-mm2-apic-virtwire-on-shutdown.i386/arch/i386/kernel/apic.c
--- linux-2.6.8.1-mm2-i8259-sysfs.x86_64/arch/i386/kernel/apic.c	Fri Aug 20 09:56:25 2004
+++ linux-2.6.8.1-mm2-apic-virtwire-on-shutdown.i386/arch/i386/kernel/apic.c	Fri Aug 20 10:26:22 2004
@@ -202,6 +202,36 @@
 		outb(0x70, 0x22);
 		outb(0x00, 0x23);
 	}
+	else {
+		/* Go back to Virtual Wire compatibility mode */
+		unsigned long value;
+
+		/* For the spurious interrupt use vector F, and enable it */
+		value = apic_read(APIC_SPIV);
+		value &= ~APIC_VECTOR_MASK;
+		value |= APIC_SPIV_APIC_ENABLED;
+		value |= 0xf;
+		apic_write_around(APIC_SPIV, value);
+
+		/* For LVT0 make it edge triggered, active high, external and enabled */
+		value = apic_read(APIC_LVT0);
+		value &= ~(APIC_MODE_MASK | APIC_SEND_PENDING |
+			APIC_INPUT_POLARITY | APIC_LVT_REMOTE_IRR |
+			APIC_LVT_LEVEL_TRIGGER | APIC_LVT_MASKED );
+		value |= APIC_LVT_REMOTE_IRR | APIC_SEND_PENDING;
+		value = SET_APIC_DELIVERY_MODE(value, APIC_MODE_EXINT);
+		apic_write_around(APIC_LVT0, value);
+
+		/* For LVT1 make it edge triggered, active high, nmi and enabled */
+		value = apic_read(APIC_LVT1);
+		value &= ~(
+			APIC_MODE_MASK | APIC_SEND_PENDING |
+			APIC_INPUT_POLARITY | APIC_LVT_REMOTE_IRR |
+			APIC_LVT_LEVEL_TRIGGER | APIC_LVT_MASKED);
+		value |= APIC_LVT_REMOTE_IRR | APIC_SEND_PENDING;
+		value = SET_APIC_DELIVERY_MODE(value, APIC_MODE_NMI);
+		apic_write_around(APIC_LVT1, value);
+	}
 }
 
 void disable_local_APIC(void)
diff -uNr linux-2.6.8.1-mm2-i8259-sysfs.x86_64/include/asm-i386/apicdef.h linux-2.6.8.1-mm2-apic-virtwire-on-shutdown.i386/include/asm-i386/apicdef.h
--- linux-2.6.8.1-mm2-i8259-sysfs.x86_64/include/asm-i386/apicdef.h	Wed Mar 10 19:55:28 2004
+++ linux-2.6.8.1-mm2-apic-virtwire-on-shutdown.i386/include/asm-i386/apicdef.h	Fri Aug 20 10:26:22 2004
@@ -86,6 +86,7 @@
 #define			APIC_LVT_REMOTE_IRR		(1<<14)
 #define			APIC_INPUT_POLARITY		(1<<13)
 #define			APIC_SEND_PENDING		(1<<12)
+#define			APIC_MODE_MASK			0x700
 #define			GET_APIC_DELIVERY_MODE(x)	(((x)>>8)&0x7)
 #define			SET_APIC_DELIVERY_MODE(x,y)	(((x)&~0x700)|((y)<<8))
 #define				APIC_MODE_FIXED		0x0

Re: [PATCH 3/14] kexec: apic-virtwire-on-shutdown.i386.patch

[Maciej W. Rozycki]

On Fri, 20 Aug 2004, Eric W. Biederman wrote:

> Restore the local apic to virtual wire mode on reboot.

 Hmm, perhaps you should check for the through-I/O-APIC Virtual Wire mode.
I've seen reports from such systems in the past.  They may not necessarily
handle the through-Local-APIC mode correctly.

  Maciej

Re: [PATCH 3/14] kexec: apic-virtwire-on-shutdown.i386.patch

[Eric W. Biederman]

"Maciej W. Rozycki" <macro@linux-mips.org> writes:

> On Fri, 20 Aug 2004, Eric W. Biederman wrote:
> 
> > Restore the local apic to virtual wire mode on reboot.
> 
>  Hmm, perhaps you should check for the through-I/O-APIC Virtual Wire mode.
> I've seen reports from such systems in the past.  They may not necessarily
> handle the through-Local-APIC mode correctly.

I do that however is done as a separate patch.

The local apic still needs to be put into virtual wire mode in that
case.


Eric

Re: [PATCH 3/14] kexec: apic-virtwire-on-shutdown.i386.patch

[Maciej W. Rozycki]

On Mon, 23 Aug 2004, Eric W. Biederman wrote:

> The local apic still needs to be put into virtual wire mode in that
> case.

 Well, depending on actual wiring you may need to mask LINT0 in this case
to avoid duplicate interrupts.  I think the safest approach would be
remembering the initial values of LVT0 and LVT1 registers of the BSP --
they are just four bytes each, so it would not be a terrible memory waste.

  Maciej

Re: [PATCH 3/14] kexec: apic-virtwire-on-shutdown.i386.patch

[Eric W. Biederman]

"Maciej W. Rozycki" <macro@linux-mips.org> writes:

> On Mon, 23 Aug 2004, Eric W. Biederman wrote:
> 
> > The local apic still needs to be put into virtual wire mode in that
> > case.
> 
>  Well, depending on actual wiring you may need to mask LINT0 in this case
> to avoid duplicate interrupts.  I think the safest approach would be
> remembering the initial values of LVT0 and LVT1 registers of the BSP --
> they are just four bytes each, so it would not be a terrible memory waste.

If I was seeing problems I guess I would worry about it.  As I have
tested on both Opteron's which require the ioapic to be in
virtual wire mode, and on Xeons which require the local apic to be in
virtual wire mode and both work I am not too concerned.

I don't think the configuration you are worrying about where
both the ioapic and the local apic can both be put into virtual
wire mode is valid according to the mp specification.  Although that
is probably a grey area in the specification.

It is more code to save off and then restore the registers,
then simply hard coding a value into them.

It is nice to have hard coded values when you can as then
you don't have to guess how something was configured on this occasion.

As my code is simpler than your suggestion and it works I'm not
a fan of changing it until I see a case where it breaks.

Eric

Re: [PATCH 3/14] kexec: apic-virtwire-on-shutdown.i386.patch

[Maciej W. Rozycki]

On Thu, 25 Aug 2004, Eric W. Biederman wrote:

> I don't think the configuration you are worrying about where
> both the ioapic and the local apic can both be put into virtual
> wire mode is valid according to the mp specification.  Although that
> is probably a grey area in the specification.

 The spec doesn't preclude a configuration where the master i8259A is
wired both to an I/O APIC input and to local APIC inputs.  If this is the
case, it's a sole discretion of the system manufacturer to choose which
route for the "virtual wire" is used.

 I don't insist on doing exact LVT restoration as at this stage it
shouldn't really matter and the firmware should reinitialize the APIC
subsystem completely anyway.  I just wanted to be sure you are aware of
the issue.

  Maciej

Re: [PATCH 3/14] kexec: apic-virtwire-on-shutdown.i386.patch

[Eric W. Biederman]

"Maciej W. Rozycki" <macro@linux-mips.org> writes:

> On Thu, 25 Aug 2004, Eric W. Biederman wrote:
> 
> > I don't think the configuration you are worrying about where
> > both the ioapic and the local apic can both be put into virtual
> > wire mode is valid according to the mp specification.  Although that
> > is probably a grey area in the specification.
> 
>  The spec doesn't preclude a configuration where the master i8259A is
> wired both to an I/O APIC input and to local APIC inputs.  If this is the
> case, it's a sole discretion of the system manufacturer to choose which
> route for the "virtual wire" is used.
> 
>  I don't insist on doing exact LVT restoration as at this stage it
> shouldn't really matter and the firmware should reinitialize the APIC
> subsystem completely anyway.  I just wanted to be sure you are aware of
> the issue.

Thanks. I will keep it in mind.

Actually now that I think about it I believe recent Intel chipsets
Tumwater/Lindenhurst work both ways but they have a bug that can
be triggered unless you are using the IOAPIC in virtual wire
mode.

In practice I still don't think it matters as everything across the
hub interface and PCI-e is message based and I don't think 2 messages
are generated.  Still I will give it some thought.

Eric