[PATCH] x86: find nr_irqs_gsi with mp_ioapic_routing

[PATCH] x86: find nr_irqs_gsi with mp_ioapic_routing

[Yinghai Lu]

Impact: find right nr_irqs_gsi on some systems.

one system has gap between gsi.
[    0.000000] ACPI: IOAPIC (id[0x04] address[0xfec00000] gsi_base[0])
[    0.000000] IOAPIC[0]: apic_id 4, version 0, address 0xfec00000, GSI 0-23
[    0.000000] ACPI: IOAPIC (id[0x05] address[0xfeafd000] gsi_base[48])
[    0.000000] IOAPIC[1]: apic_id 5, version 0, address 0xfeafd000, GSI 48-54
[    0.000000] ACPI: IOAPIC (id[0x06] address[0xfeafc000] gsi_base[56])
[    0.000000] IOAPIC[2]: apic_id 6, version 0, address 0xfeafc000, GSI 56-62
...
[    0.000000] nr_irqs_gsi: 38

so nr_irqs_gsi is not right. some irq for MSI will overwrite with io_apic.

need to get that with acpi_probe_gsi when acpi io_apic is used

Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 arch/x86/include/asm/mpspec.h |    5 +++++
 arch/x86/kernel/acpi/boot.c   |   23 +++++++++++++++++++++++
 arch/x86/kernel/io_apic.c     |   20 +++++++++++++++-----
 3 files changed, 43 insertions(+), 5 deletions(-)

Index: linux-2.6/arch/x86/include/asm/mpspec.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/mpspec.h
+++ linux-2.6/arch/x86/include/asm/mpspec.h
@@ -73,6 +73,7 @@ extern void mp_override_legacy_irq(u8 bu
 				   u32 gsi);
 extern void mp_config_acpi_legacy_irqs(void);
 extern int mp_register_gsi(u32 gsi, int edge_level, int active_high_low);
+extern int acpi_probe_gsi(void);
 #ifdef CONFIG_X86_IO_APIC
 extern int mp_config_acpi_gsi(unsigned char number, unsigned int devfn, u8 pin,
 				u32 gsi, int triggering, int polarity);
@@ -83,6 +84,10 @@ mp_config_acpi_gsi(unsigned char number,
 {
 	return 0;
 }
+static inline int acpi_probe_gsi(void)
+{
+	return 0;
+}
 #endif
 #endif /* CONFIG_ACPI */
 
Index: linux-2.6/arch/x86/kernel/acpi/boot.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/acpi/boot.c
+++ linux-2.6/arch/x86/kernel/acpi/boot.c
@@ -944,6 +944,29 @@ void __init mp_register_ioapic(int id, u
 	nr_ioapics++;
 }
 
+int __init acpi_probe_gsi(void)
+{
+	int idx;
+	int gsi;
+	int max_gsi = 0;
+
+	if (acpi_disabled)
+		return 0;
+
+	if (!acpi_ioapic)
+		return 0;
+
+	max_gsi = 0;
+	for (idx = 0; idx < nr_ioapics; idx++) {
+		gsi = mp_ioapic_routing[idx].gsi_end;
+
+		if (gsi > max_gsi)
+			max_gsi = gsi;
+	}
+
+	return max_gsi + 1;
+}
+
 static void assign_to_mp_irq(struct mpc_intsrc *m,
 				    struct mpc_intsrc *mp_irq)
 {
Index: linux-2.6/arch/x86/kernel/io_apic.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/io_apic.c
+++ linux-2.6/arch/x86/kernel/io_apic.c
@@ -3810,14 +3810,24 @@ int __init io_apic_get_redir_entries (in
 
 void __init probe_nr_irqs_gsi(void)
 {
-	int idx;
 	int nr = 0;
 
-	for (idx = 0; idx < nr_ioapics; idx++)
-		nr += io_apic_get_redir_entries(idx) + 1;
-
-	if (nr > nr_irqs_gsi)
+	nr = acpi_probe_gsi();
+	if (nr > nr_irqs_gsi) {
 		nr_irqs_gsi = nr;
+	} else {
+		/* for acpi=off or acpi is not compiled in */
+		int idx;
+
+		nr = 0;
+		for (idx = 0; idx < nr_ioapics; idx++)
+			nr += io_apic_get_redir_entries(idx) + 1;
+
+		if (nr > nr_irqs_gsi)
+			nr_irqs_gsi = nr;
+	}
+
+	printk(KERN_DEBUG "nr_irqs_gsi: %d\n", nr_irqs_gsi);
 }
 
 #ifdef CONFIG_SPARSE_IRQ

[PATCH] x86/irq: optimizing nr_irqs

[Yinghai Lu]

Impact: more depend on cards to be used

depend on nr_irq_gsi more, and have a ratio for MSI

Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 arch/x86/kernel/io_apic.c |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

Index: linux-2.6/arch/x86/kernel/io_apic.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/io_apic.c
+++ linux-2.6/arch/x86/kernel/io_apic.c
@@ -3479,9 +3479,9 @@ int arch_setup_msi_irqs(struct pci_dev *
 	sub_handle = 0;
 	list_for_each_entry(msidesc, &dev->msi_list, list) {
 		irq = create_irq_nr(irq_want);
-		irq_want++;
 		if (irq == 0)
 			return -1;
+		irq_want = irq + 1;
 #ifdef CONFIG_INTR_REMAP
 		if (!intr_remapping_enabled)
 			goto no_ir;
@@ -3835,11 +3835,14 @@ int __init arch_probe_nr_irqs(void)
 {
 	int nr;
 
-	nr = ((8 * nr_cpu_ids) > (32 * nr_ioapics) ?
-		(NR_VECTORS + (8 * nr_cpu_ids)) :
-		(NR_VECTORS + (32 * nr_ioapics)));
-
-	if (nr < nr_irqs && nr > nr_irqs_gsi)
+	nr = nr_irqs_gsi + 8 * nr_cpu_ids;
+#if defined(CONFIG_PCI_MSI) || defined(CONFIG_HT_IRQ)
+	/*
+	 * for MSI and HT dyn irq
+	 */
+	nr += nr_irqs_gsi * 16;
+#endif
+	if (nr < (NR_VECTORS * nr_cpu_ids))
 		nr_irqs = nr;
 
 	return 0;

Re: [PATCH] x86: find nr_irqs_gsi with mp_ioapic_routing

[Len Brown]

> Impact: find right nr_irqs_gsi on some systems.
> 
> one system has gap between gsi.
> [    0.000000] ACPI: IOAPIC (id[0x04] address[0xfec00000] gsi_base[0])
> [    0.000000] IOAPIC[0]: apic_id 4, version 0, address 0xfec00000, GSI 0-23
> [    0.000000] ACPI: IOAPIC (id[0x05] address[0xfeafd000] gsi_base[48])
> [    0.000000] IOAPIC[1]: apic_id 5, version 0, address 0xfeafd000, GSI 48-54
> [    0.000000] ACPI: IOAPIC (id[0x06] address[0xfeafc000] gsi_base[56])
> [    0.000000] IOAPIC[2]: apic_id 6, version 0, address 0xfeafc000, GSI 56-62
> ...
> [    0.000000] nr_irqs_gsi: 38

I've never seen gaps in GSIs.
I've never seen IOAPICs with 7 redirection table entries.

This system looks quite broken even before the probe for nr_irqs_gsi.
Do you have more information on it?

thanks,
-Len
--
Intel Open Source Technology Center

Re: [PATCH] x86: find nr_irqs_gsi with mp_ioapic_routing

[Yinghai Lu]

Len Brown wrote:
> 
> 
>> Impact: find right nr_irqs_gsi on some systems.
>>
>> one system has gap between gsi.
>> [    0.000000] ACPI: IOAPIC (id[0x04] address[0xfec00000] gsi_base[0])
>> [    0.000000] IOAPIC[0]: apic_id 4, version 0, address 0xfec00000, GSI 0-23
>> [    0.000000] ACPI: IOAPIC (id[0x05] address[0xfeafd000] gsi_base[48])
>> [    0.000000] IOAPIC[1]: apic_id 5, version 0, address 0xfeafd000, GSI 48-54
>> [    0.000000] ACPI: IOAPIC (id[0x06] address[0xfeafc000] gsi_base[56])
>> [    0.000000] IOAPIC[2]: apic_id 6, version 0, address 0xfeafc000, GSI 56-62
>> ...
>> [    0.000000] nr_irqs_gsi: 38
> 
> I've never seen gaps in GSIs.
> I've never seen IOAPICs with 7 redirection table entries.
> 
> This system looks quite broken even before the probe for nr_irqs_gsi.
> Do you have more information on it?

it is one AMD based system from Sun.
it has two hypertransport chains.
one: 8132 + ck804
one: io4

when 8 sockets are installed, will get
[    0.000000] ACPI: IOAPIC (id[0x00] address[0xfec00000] gsi_base[0])
[    0.000000] IOAPIC[0]: apic_id 0, version 0, address 0xfec00000, GSI 0-23
[    0.000000] ACPI: IOAPIC (id[0x01] address[0xfdefd000] gsi_base[48])
[    0.000000] IOAPIC[1]: apic_id 1, version 0, address 0xfdefd000, GSI 48-54
[    0.000000] ACPI: IOAPIC (id[0x02] address[0xfdefc000] gsi_base[56])
[    0.000000] IOAPIC[2]: apic_id 2, version 0, address 0xfdefc000, GSI 56-62
[    0.000000] ACPI: IOAPIC (id[0x03] address[0xfeaff000] gsi_base[24])
[    0.000000] IOAPIC[3]: apic_id 3, version 0, address 0xfeaff000, GSI 24-47


when 2 sockets are installed, only HT chains is used. will get
[    0.000000] ACPI: IOAPIC (id[0x04] address[0xfec00000] gsi_base[0])
[    0.000000] IOAPIC[0]: apic_id 4, version 0, address 0xfec00000, GSI 0-23
[    0.000000] ACPI: IOAPIC (id[0x05] address[0xfeafd000] gsi_base[48])
[    0.000000] IOAPIC[1]: apic_id 5, version 0, address 0xfeafd000, GSI 48-54
[    0.000000] ACPI: IOAPIC (id[0x06] address[0xfeafc000] gsi_base[56])
[    0.000000] IOAPIC[2]: apic_id 6, version 0, address 0xfeafc000, GSI 56-62

acpi madt ioapic-entries does include gsi_base field.

amd 8131: has 4 gsi
amd 8132: has 7 gsi, but only 3 can be used.

anyway that system is not broken, and it is quite solid.

this patch seems to be a 2.6.29 material.

YH

Re: [PATCH] x86: find nr_irqs_gsi with mp_ioapic_routing

[Len Brown]

> >> Impact: find right nr_irqs_gsi on some systems.
> >>
> >> one system has gap between gsi.
> >> [    0.000000] ACPI: IOAPIC (id[0x04] address[0xfec00000] gsi_base[0])
> >> [    0.000000] IOAPIC[0]: apic_id 4, version 0, address 0xfec00000, GSI 0-23
> >> [    0.000000] ACPI: IOAPIC (id[0x05] address[0xfeafd000] gsi_base[48])
> >> [    0.000000] IOAPIC[1]: apic_id 5, version 0, address 0xfeafd000, GSI 48-54
> >> [    0.000000] ACPI: IOAPIC (id[0x06] address[0xfeafc000] gsi_base[56])
> >> [    0.000000] IOAPIC[2]: apic_id 6, version 0, address 0xfeafc000, GSI 56-62
> >> ...
> >> [    0.000000] nr_irqs_gsi: 38
> > 
> > I've never seen gaps in GSIs.
> > I've never seen IOAPICs with 7 redirection table entries.
> > 
> > This system looks quite broken even before the probe for nr_irqs_gsi.
> > Do you have more information on it?
> 
> it is one AMD based system from Sun.
> it has two hypertransport chains.
> one: 8132 + ck804
> one: io4
> 
> when 8 sockets are installed, will get
> [    0.000000] ACPI: IOAPIC (id[0x00] address[0xfec00000] gsi_base[0])
> [    0.000000] IOAPIC[0]: apic_id 0, version 0, address 0xfec00000, GSI 0-23
> [    0.000000] ACPI: IOAPIC (id[0x01] address[0xfdefd000] gsi_base[48])
> [    0.000000] IOAPIC[1]: apic_id 1, version 0, address 0xfdefd000, GSI 48-54
> [    0.000000] ACPI: IOAPIC (id[0x02] address[0xfdefc000] gsi_base[56])
> [    0.000000] IOAPIC[2]: apic_id 2, version 0, address 0xfdefc000, GSI 56-62
> [    0.000000] ACPI: IOAPIC (id[0x03] address[0xfeaff000] gsi_base[24])
> [    0.000000] IOAPIC[3]: apic_id 3, version 0, address 0xfeaff000, GSI 24-47
> 
> 
> when 2 sockets are installed, only HT chains is used. will get
> [    0.000000] ACPI: IOAPIC (id[0x04] address[0xfec00000] gsi_base[0])
> [    0.000000] IOAPIC[0]: apic_id 4, version 0, address 0xfec00000, GSI 0-23
> [    0.000000] ACPI: IOAPIC (id[0x05] address[0xfeafd000] gsi_base[48])
> [    0.000000] IOAPIC[1]: apic_id 5, version 0, address 0xfeafd000, GSI 48-54
> [    0.000000] ACPI: IOAPIC (id[0x06] address[0xfeafc000] gsi_base[56])
> [    0.000000] IOAPIC[2]: apic_id 6, version 0, address 0xfeafc000, GSI 56-62
> 
> acpi madt ioapic-entries does include gsi_base field.
> 
> amd 8131: has 4 gsi
> amd 8132: has 7 gsi, but only 3 can be used.
> 
> anyway that system is not broken, and it is quite solid.

I don't know if it violates the ACPI spec to have gaps in the GSI's,
but it does violate my expectations when I read the spec -- so i guess
that "unexpected" or "unconventional" may be a better word than "broken".

At the same time, "unexpected" and "unconventional" BIOS implementations
cause things like "broken" OS -- thus the need for your patch:-)

> this patch seems to be a 2.6.29 material.

I agree.

thanks,
Len Brown, Intel Open Source Technology Center

[PATCH] x86: use NR_IRQS_LEGACY to replace 16

[Yinghai Lu]

Impact: cleanup

also could kill platform_legacy_irq

Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 arch/x86/include/asm/hw_irq.h |    4 +---
 arch/x86/kernel/io_apic.c     |    8 ++++----
 2 files changed, 5 insertions(+), 7 deletions(-)

Index: linux-2.6/arch/x86/include/asm/hw_irq.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/hw_irq.h
+++ linux-2.6/arch/x86/include/asm/hw_irq.h
@@ -25,8 +25,6 @@
 #include <asm/irq.h>
 #include <asm/sections.h>
 
-#define platform_legacy_irq(irq)	((irq) < 16)
-
 /* Interrupt handlers registered during init_IRQ */
 extern void apic_timer_interrupt(void);
 extern void error_interrupt(void);
@@ -60,7 +58,7 @@ extern void make_8259A_irq(unsigned int
 extern void init_8259A(int aeoi);
 
 /* IOAPIC */
-#define IO_APIC_IRQ(x) (((x) >= 16) || ((1<<(x)) & io_apic_irqs))
+#define IO_APIC_IRQ(x) (((x) >= NR_IRQS_LEGACY) || ((1<<(x)) & io_apic_irqs))
 extern unsigned long io_apic_irqs;
 
 extern void init_VISWS_APIC_irqs(void);
Index: linux-2.6/arch/x86/kernel/io_apic.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/io_apic.c
+++ linux-2.6/arch/x86/kernel/io_apic.c
@@ -3168,6 +3168,7 @@ static int __init ioapic_init_sysfs(void
 
 device_initcall(ioapic_init_sysfs);
 
+static int nr_irqs_gsi = NR_IRQS_LEGACY;
 /*
  * Dynamic irq allocate and deallocation
  */
@@ -3182,11 +3183,11 @@ unsigned int create_irq_nr(unsigned int
 	struct irq_desc *desc_new = NULL;
 
 	irq = 0;
+	if (irq_want < nr_irqs_gsi)
+		irq_want = nr_irqs_gsi;
+
 	spin_lock_irqsave(&vector_lock, flags);
 	for (new = irq_want; new < nr_irqs; new++) {
-		if (platform_legacy_irq(new))
-			continue;
-
 		desc_new = irq_to_desc_alloc_cpu(new, cpu);
 		if (!desc_new) {
 			printk(KERN_INFO "can not get irq_desc for %d\n", new);
@@ -3211,7 +3212,6 @@ unsigned int create_irq_nr(unsigned int
 	return irq;
 }
 
-static int nr_irqs_gsi = NR_IRQS_LEGACY;
 int create_irq(void)
 {
 	unsigned int irq_want;

[PATCH] x86/irq: optimizing nr_irqs -v2

[Yinghai Lu]

Impact: more depend on cards to be used

depend on nr_irq_gsi more, and have a ratio for MSI

v2: make nr_irqs shoule less than NR_VECTORS * nr_cpu_ids
   aka if only one cpu, we only can support nr_irqs = NR_VECTORS

Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 arch/x86/kernel/io_apic.c |   16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

Index: linux-2.6/arch/x86/kernel/io_apic.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/io_apic.c
+++ linux-2.6/arch/x86/kernel/io_apic.c
@@ -3482,9 +3482,9 @@ int arch_setup_msi_irqs(struct pci_dev *
 	sub_handle = 0;
 	list_for_each_entry(msidesc, &dev->msi_list, list) {
 		irq = create_irq_nr(irq_want);
-		irq_want++;
 		if (irq == 0)
 			return -1;
+		irq_want = irq + 1;
 #ifdef CONFIG_INTR_REMAP
 		if (!intr_remapping_enabled)
 			goto no_ir;
@@ -3838,11 +3838,17 @@ int __init arch_probe_nr_irqs(void)
 {
 	int nr;
 
-	nr = ((8 * nr_cpu_ids) > (32 * nr_ioapics) ?
-		(NR_VECTORS + (8 * nr_cpu_ids)) :
-		(NR_VECTORS + (32 * nr_ioapics)));
+	if (nr_irqs > (NR_VECTORS * nr_cpu_ids))
+		nr_irqs = NR_VECTORS * nr_cpu_ids;
 
-	if (nr < nr_irqs && nr > nr_irqs_gsi)
+	nr = nr_irqs_gsi + 8 * nr_cpu_ids;
+#if defined(CONFIG_PCI_MSI) || defined(CONFIG_HT_IRQ)
+	/*
+	 * for MSI and HT dyn irq
+	 */
+	nr += nr_irqs_gsi * 16;
+#endif
+	if (nr < nr_irqs)
 		nr_irqs = nr;
 
 	return 0;

Re: [PATCH] x86: find nr_irqs_gsi with mp_ioapic_routing

[Ingo Molnar]

* Yinghai Lu <yinghai@kernel.org> wrote:

> 
> Impact: find right nr_irqs_gsi on some systems.
> 
> one system has gap between gsi.
> [    0.000000] ACPI: IOAPIC (id[0x04] address[0xfec00000] gsi_base[0])
> [    0.000000] IOAPIC[0]: apic_id 4, version 0, address 0xfec00000, GSI 0-23
> [    0.000000] ACPI: IOAPIC (id[0x05] address[0xfeafd000] gsi_base[48])
> [    0.000000] IOAPIC[1]: apic_id 5, version 0, address 0xfeafd000, GSI 48-54
> [    0.000000] ACPI: IOAPIC (id[0x06] address[0xfeafc000] gsi_base[56])
> [    0.000000] IOAPIC[2]: apic_id 6, version 0, address 0xfeafc000, GSI 56-62
> ...
> [    0.000000] nr_irqs_gsi: 38
> 
> so nr_irqs_gsi is not right. some irq for MSI will overwrite with io_apic.
> 
> need to get that with acpi_probe_gsi when acpi io_apic is used
> 
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> 
> ---
>  arch/x86/include/asm/mpspec.h |    5 +++++
>  arch/x86/kernel/acpi/boot.c   |   23 +++++++++++++++++++++++
>  arch/x86/kernel/io_apic.c     |   20 +++++++++++++++-----
>  3 files changed, 43 insertions(+), 5 deletions(-)

Applied to tip/x86/apic, thanks Yinghai!

Could you please send one against linus/master too please? (there's conflicts)

	Ingo

Re: [PATCH] x86/irq: optimizing nr_irqs -v2

[Ingo Molnar]

* Yinghai Lu <yinghai@kernel.org> wrote:

> 
> Impact: more depend on cards to be used
> 
> depend on nr_irq_gsi more, and have a ratio for MSI
> 
> v2: make nr_irqs shoule less than NR_VECTORS * nr_cpu_ids
>    aka if only one cpu, we only can support nr_irqs = NR_VECTORS
> 
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> 
> ---
>  arch/x86/kernel/io_apic.c |   16 +++++++++++-----
>  1 file changed, 11 insertions(+), 5 deletions(-)

Applied to tip/x86/apic, thanks Yinghai!

	Ingo

Re: [PATCH] x86: use NR_IRQS_LEGACY to replace 16

[Ingo Molnar]

* Yinghai Lu <yinghai@kernel.org> wrote:

> 
> Impact: cleanup
> 
> also could kill platform_legacy_irq
> 
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> 
> ---
>  arch/x86/include/asm/hw_irq.h |    4 +---
>  arch/x86/kernel/io_apic.c     |    8 ++++----
>  2 files changed, 5 insertions(+), 7 deletions(-)

Applied to tip/x86/apic, thanks Yinghai!

	Ingo

[PATCH] x86: find nr_irqs_gsi with mp_ioapic_routing v3

[Yinghai Lu]

Impact: find right nr_irqs_gsi on some systems.

one system has gap between gsi.
[    0.000000] ACPI: IOAPIC (id[0x04] address[0xfec00000] gsi_base[0])
[    0.000000] IOAPIC[0]: apic_id 4, version 0, address 0xfec00000, GSI 0-23
[    0.000000] ACPI: IOAPIC (id[0x05] address[0xfeafd000] gsi_base[48])
[    0.000000] IOAPIC[1]: apic_id 5, version 0, address 0xfeafd000, GSI 48-54
[    0.000000] ACPI: IOAPIC (id[0x06] address[0xfeafc000] gsi_base[56])
[    0.000000] IOAPIC[2]: apic_id 6, version 0, address 0xfeafc000, GSI 56-62
...
[    0.000000] nr_irqs_gsi: 38

so nr_irqs_gsi is not right. some irq for MSI will overwrite with io_apic.

need to get that with acpi_probe_gsi when acpi io_apic is used

v2: Ingo pointed out inline acpi_probe_gsi() should be with !CONFIG_ACPI

v3: against current upstream for 2.6.29, because it is 2.6.29 material

Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 arch/x86/include/asm/mpspec.h |    6 ++++++
 arch/x86/kernel/acpi/boot.c   |   23 +++++++++++++++++++++++
 arch/x86/kernel/io_apic.c     |   20 +++++++++++++++-----
 3 files changed, 44 insertions(+), 5 deletions(-)

Index: linux-2.6/arch/x86/include/asm/mpspec.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/mpspec.h
+++ linux-2.6/arch/x86/include/asm/mpspec.h
@@ -60,6 +60,7 @@ extern void mp_override_legacy_irq(u8 bu
 				   u32 gsi);
 extern void mp_config_acpi_legacy_irqs(void);
 extern int mp_register_gsi(u32 gsi, int edge_level, int active_high_low);
+extern int acpi_probe_gsi(void);
 #ifdef CONFIG_X86_IO_APIC
 extern int mp_config_acpi_gsi(unsigned char number, unsigned int devfn, u8 pin,
 				u32 gsi, int triggering, int polarity);
@@ -71,6 +72,11 @@ mp_config_acpi_gsi(unsigned char number,
 	return 0;
 }
 #endif
+#else /* !CONFIG_ACPI */
+static inline int acpi_probe_gsi(void)
+{
+	return 0;
+}
 #endif /* CONFIG_ACPI */
 
 #define PHYSID_ARRAY_SIZE	BITS_TO_LONGS(MAX_APICS)
Index: linux-2.6/arch/x86/kernel/io_apic.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/io_apic.c
+++ linux-2.6/arch/x86/kernel/io_apic.c
@@ -3841,14 +3841,24 @@ int __init io_apic_get_redir_entries (in
 
 void __init probe_nr_irqs_gsi(void)
 {
-	int idx;
 	int nr = 0;
 
-	for (idx = 0; idx < nr_ioapics; idx++)
-		nr += io_apic_get_redir_entries(idx) + 1;
-
-	if (nr > nr_irqs_gsi)
+	nr = acpi_probe_gsi();
+	if (nr > nr_irqs_gsi) {
 		nr_irqs_gsi = nr;
+	} else {
+		/* for acpi=off or acpi is not compiled in */
+		int idx;
+
+		nr = 0;
+		for (idx = 0; idx < nr_ioapics; idx++)
+			nr += io_apic_get_redir_entries(idx) + 1;
+
+		if (nr > nr_irqs_gsi)
+			nr_irqs_gsi = nr;
+	}
+
+	printk(KERN_DEBUG "nr_irqs_gsi: %d\n", nr_irqs_gsi);
 }
 
 /* --------------------------------------------------------------------------
Index: linux-2.6/arch/x86/kernel/acpi/boot.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/acpi/boot.c
+++ linux-2.6/arch/x86/kernel/acpi/boot.c
@@ -973,6 +973,29 @@ void __init mp_register_ioapic(int id, u
 	nr_ioapics++;
 }
 
+int __init acpi_probe_gsi(void)
+{
+	int idx;
+	int gsi;
+	int max_gsi = 0;
+
+	if (acpi_disabled)
+		return 0;
+
+	if (!acpi_ioapic)
+		return 0;
+
+	max_gsi = 0;
+	for (idx = 0; idx < nr_ioapics; idx++) {
+		gsi = mp_ioapic_routing[idx].gsi_end;
+
+		if (gsi > max_gsi)
+			max_gsi = gsi;
+	}
+
+	return max_gsi + 1;
+}
+
 static void assign_to_mp_irq(struct mp_config_intsrc *m,
 				    struct mp_config_intsrc *mp_irq)
 {