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Message-ID: <4C57DACF.1090503@kernel.org>
Date: Tue, 03 Aug 2010 02:01:03 -0700
From: Yinghai Lu <yinghai@...nel.org>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
CC: Dave Airlie <airlied@...il.com>,
LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>
Subject: Re: oops in ioapic_write_entry
On 08/03/2010 01:56 AM, Eric W. Biederman wrote:
> Yinghai Lu <yinghai@...nel.org> writes:
>
>> On 08/03/2010 01:00 AM, Eric W. Biederman wrote:
>>> Yinghai Lu <yinghai@...nel.org> writes:
>>>
>>>>>> Index: linux-2.6/arch/x86/kernel/apic/io_apic.c
>>>>>> ===================================================================
>>>>>> --- linux-2.6.orig/arch/x86/kernel/apic/io_apic.c
>>>>>> +++ linux-2.6/arch/x86/kernel/apic/io_apic.c
>>>>>> @@ -1029,10 +1029,7 @@ static int pin_2_irq(int idx, int apic,
>>>>>> } else {
>>>>>> u32 gsi = mp_gsi_routing[apic].gsi_base + pin;
>>>>>>
>>>>>> - if (gsi >= NR_IRQS_LEGACY)
>>>>>> - irq = gsi;
>>>>>> - else
>>>>>> - irq = gsi_top + gsi;
>>>>>> + irq = gsi_to_irq(gsi);
>>>>>> }
>>>>>>
>>>>>> #ifdef CONFIG_X86_32
>>>>
>>>> what is the point for making irq = gsi_top + gsi when mptable is used instead of acpi?
>>>
>>> Because it is only convention that when mptables are used that the
>>> first apic pins 0-15 are the ISA irqs. This thread witnessed and a
>>> pci irq that came in pin < 16 that was not an ISA irq. The truly rare
>>> and exotic case would be for the ISA irqs to be outside the first 16
>>> ioapic pins but the es7000 did exactly that.
>>
>> nvidia chipset if acpi is enabled, external pci device will use ioapic from 16 to 23.
>>
>> if mptable is used, external pci device will not use pin from 16 to 23..., and lot of devices will share same pin.
>
> Exactly. Pins < 16 are not necessarily ISA irqs, and can be possibly
> shared level triggered PCI irqs. Unfortunately there are strange
> boards like the es7000 where pins > 16 are ISA irqs.
>
> The other thing that is gained by having pin_2_irq always remap pins <
> 16 is we can get away with the numerous hard codes in the arch/x86 and elsewhere
> that assume irq < 16 is an ISA irq.
how about this one ?
---
arch/x86/kernel/apic/io_apic.c | 31 ++++++++++++++++++++++++++++---
1 file changed, 28 insertions(+), 3 deletions(-)
Index: linux-2.6/arch/x86/kernel/apic/io_apic.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic/io_apic.c
+++ linux-2.6/arch/x86/kernel/apic/io_apic.c
@@ -1013,6 +1013,28 @@ static inline int irq_trigger(int idx)
return MPBIOS_trigger(idx);
}
+static int shared_with_legacy(int apic, int pin)
+{
+ int i;
+
+ for (i = 0; i < mp_irq_entries; i++) {
+ int bus = mp_irqs[i].srcbus;
+
+ if (!test_bit(bus, mp_bus_not_pci))
+ continue;
+
+ if (mp_ioapics[apic].apicid != mp_irqs[i].dstapic)
+ continue;
+
+ if (mp_irqs[i].dstirq != pin)
+ continue;
+
+ return mp_irqs[i].srcbusirq;
+ }
+
+ return -1;
+}
+
static int pin_2_irq(int idx, int apic, int pin)
{
int irq;
@@ -1029,10 +1051,13 @@ static int pin_2_irq(int idx, int apic,
} else {
u32 gsi = mp_gsi_routing[apic].gsi_base + pin;
- if (gsi >= NR_IRQS_LEGACY)
+ if (gsi >= NR_IRQS_LEGACY) {
irq = gsi;
- else
- irq = gsi_top + gsi;
+ } else {
+ irq = shared_with_legacy(apic, pin);
+ if (irq < 0)
+ irq = gsi_top + gsi;
+ }
}
#ifdef CONFIG_X86_32
--
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