linux-kernel - Re: oops in ioapic_write

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Date:	Tue, 03 Aug 2010 02:36:42 -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 02:15 AM, Eric W. Biederman wrote:
> Yinghai Lu <yinghai@...nel.org> writes:
> 
>> 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 ?
> 
> You can't share an edge triggered ISA irq, it isn't really physically
> possible.  So I don't see how this extra complexity will change anything.
> 

Dave's system mptble:

MPTABLE: OEM ID: DELL    
MPTABLE: Product ID: Dell XPS710 
MPTABLE: APIC at: 0xFEE00000
Processor #0 (Bootup-CPU)
Processor #1
Bus #0 is PCI   
Bus #1 is PCI   
Bus #2 is PCI   
Bus #3 is PCI   
Bus #4 is PCI   
Bus #5 is PCI   
Bus #6 is PCI   
Bus #7 is PCI   
Bus #8 is PCI   
Bus #9 is PCI   
Bus #10 is ISA   
I/O APIC #8 Version 17 at 0xFEC00000.
IOAPIC[0]: apic_id 8, version 17, address 0xfec00000, GSI 0-23
Int: type 0, pol 0, trig 0, bus 0a, IRQ 00, APIC ID 8, APIC INT 00
Int: type 0, pol 0, trig 0, bus 0a, IRQ 01, APIC ID 8, APIC INT 01
Int: type 3, pol 1, trig 1, bus 0a, IRQ 00, APIC ID 8, APIC INT 02
Int: type 0, pol 0, trig 0, bus 0a, IRQ 03, APIC ID 8, APIC INT 03
Int: type 0, pol 0, trig 0, bus 0a, IRQ 04, APIC ID 8, APIC INT 04
Int: type 0, pol 0, trig 0, bus 0a, IRQ 05, APIC ID 8, APIC INT 05
Int: type 0, pol 0, trig 0, bus 0a, IRQ 06, APIC ID 8, APIC INT 06
Int: type 0, pol 0, trig 0, bus 0a, IRQ 07, APIC ID 8, APIC INT 07
Int: type 0, pol 0, trig 0, bus 0a, IRQ 08, APIC ID 8, APIC INT 08
Int: type 0, pol 0, trig 0, bus 0a, IRQ 09, APIC ID 8, APIC INT 09
Int: type 0, pol 0, trig 0, bus 0a, IRQ 0a, APIC ID 8, APIC INT 0a
Int: type 0, pol 0, trig 0, bus 0a, IRQ 0b, APIC ID 8, APIC INT 0b
Int: type 0, pol 0, trig 0, bus 0a, IRQ 0c, APIC ID 8, APIC INT 0c
Int: type 0, pol 0, trig 0, bus 0a, IRQ 0e, APIC ID 8, APIC INT 0e
Int: type 0, pol 0, trig 0, bus 0a, IRQ 0f, APIC ID 8, APIC INT 0f
Int: type 0, pol 0, trig 0, bus 00, IRQ 28, APIC ID 8, APIC INT 09
Int: type 0, pol 0, trig 0, bus 00, IRQ 2c, APIC ID 8, APIC INT 0a
Int: type 0, pol 0, trig 0, bus 00, IRQ 2d, APIC ID 8, APIC INT 0a
Int: type 0, pol 0, trig 0, bus 00, IRQ 34, APIC ID 8, APIC INT 0e
Int: type 0, pol 0, trig 0, bus 00, IRQ 38, APIC ID 8, APIC INT 0b
Int: type 0, pol 0, trig 0, bus 00, IRQ 38, APIC ID 8, APIC INT 0b
Int: type 0, pol 0, trig 0, bus 00, IRQ 38, APIC ID 8, APIC INT 0b
Int: type 0, pol 0, trig 0, bus 00, IRQ 34, APIC ID 8, APIC INT 09
Int: type 0, pol 0, trig 0, bus 01, IRQ 00, APIC ID 8, APIC INT 0b
Int: type 0, pol 0, trig 0, bus 01, IRQ 01, APIC ID 8, APIC INT 0a
Int: type 0, pol 0, trig 0, bus 01, IRQ 02, APIC ID 8, APIC INT 09
Int: type 0, pol 0, trig 0, bus 03, IRQ 00, APIC ID 0, APIC INT 10
Int: type 0, pol 0, trig 0, bus 04, IRQ 00, APIC ID 0, APIC INT 10
Int: type 0, pol 0, trig 0, bus 04, IRQ 01, APIC ID 0, APIC INT 11
Int: type 0, pol 0, trig 0, bus 05, IRQ 00, APIC ID 8, APIC INT 0a
Int: type 0, pol 0, trig 0, bus 05, IRQ 01, APIC ID 8, APIC INT 09
Int: type 0, pol 0, trig 0, bus 05, IRQ 03, APIC ID 8, APIC INT 0b
Int: type 0, pol 0, trig 0, bus 06, IRQ 00, APIC ID 8, APIC INT 09
Int: type 0, pol 0, trig 0, bus 07, IRQ 0c, APIC ID 8, APIC INT 09
Int: type 0, pol 0, trig 0, bus 07, IRQ 0e, APIC ID 8, APIC INT 0b
Int: type 0, pol 0, trig 0, bus 07, IRQ 0f, APIC ID 8, APIC INT 0a
Int: type 0, pol 0, trig 0, bus 07, IRQ 10, APIC ID 8, APIC INT 0b
Int: type 0, pol 0, trig 0, bus 07, IRQ 11, APIC ID 8, APIC INT 0a
Int: type 0, pol 0, trig 0, bus 07, IRQ 12, APIC ID 8, APIC INT 09
Int: type 0, pol 0, trig 0, bus 07, IRQ 14, APIC ID 8, APIC INT 0a
Int: type 0, pol 0, trig 0, bus 07, IRQ 15, APIC ID 8, APIC INT 09
Int: type 0, pol 0, trig 0, bus 07, IRQ 17, APIC ID 8, APIC INT 0b
Int: type 0, pol 0, trig 0, bus 07, IRQ 28, APIC ID 8, APIC INT 09
Int: type 0, pol 0, trig 0, bus 08, IRQ 00, APIC ID 8, APIC INT 0a
Int: type 0, pol 0, trig 0, bus 08, IRQ 01, APIC ID 8, APIC INT 09
Int: type 0, pol 0, trig 0, bus 08, IRQ 03, APIC ID 8, APIC INT 0b
Int: type 0, pol 0, trig 0, bus 09, IRQ 00, APIC ID 8, APIC INT 0b
Int: type 0, pol 0, trig 0, bus 09, IRQ 01, APIC ID 8, APIC INT 0a
Int: type 0, pol 0, trig 0, bus 09, IRQ 02, APIC ID 8, APIC INT 09
Lint: type 3, pol 1, trig 1, bus 0a, IRQ 00, APIC ID ff, APIC LINT 00
Lint: type 1, pol 1, trig 1, bus 0a, IRQ 00, APIC ID ff, APIC LINT 01
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