linux-kernel - Re: [PATCH] x86/ACPI: Fix regression caused by 16ee7b3dcc56

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Date:	Fri, 10 Apr 2015 08:19:44 +0200
From:	Jim Bos <jim876@...all.nl>
To:	Jiang Liu <jiang.liu@...ux.intel.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-pm@...r.kernel.org
Subject: Re: [PATCH] x86/ACPI: Fix regression caused by 16ee7b3dcc56

On 04/10/2015 03:56 AM, Jiang Liu wrote:
> On 2015/4/10 0:41, Jim Bos wrote:
>> On 04/09/2015 12:15 PM, Jiang Liu wrote:
>>> On 2015/4/8 23:51, Jim Bos wrote:
>>>> On 04/08/2015 07:26 AM, Jiang Liu wrote:
>>>>> On 2015/4/8 0:49, Jim Bos wrote:
>>>>>> On 04/07/2015 04:34 PM, Jiang Liu wrote:
> <snip>
>>> Hi Jim,
>>> 	I'm really confused. I can't even explain why my previous
>>> patch fixes the issue on AMD geode board now:(
>>>
>>> For the Dell laptop, seems you have:
>>> 1) build a kernel with Local APIC and IOAPIC enabled
>>> 2) lapic is disabled by BIOS, so there's no ACPI MADT(APIC)
>>> table at all.
>>> That means the laptop is working with 8259 PICs only.
>>> There's little change between 3.16 and 4.0 related to 8259.
>>>
>>> For the AMD geode board, I still think original code is right.
>>> I can't explain why the patch fix the issue.
>>>
>>> So could you please help to:
>>> 1) Try to enable lapic on Dell laptop in BIOS
>>> 2) Dump acpi tables and dmesg on AMD board
>>>
>>> If that still doesn't help, I will try to send you some
>>> debug patches to gather more info.
>>> Thanks!
>>> Gerry
>>>> _
>>>> Jim
>>>>
>>>
>>
>> Gerry,
>>
>> As you mentioned your patch shouldn't make a difference, run some more
>> tests, as it turns out:
>> - geode system  broken on 3.16+ up to and including 3.19, however, on
>> plain 4.0-rc6 it works!  Root cause appears to be there isn't an ACPI
>> interrupt assigned in non-working kernels.
>> - other system I got my hands on: Pentium(R) CPU G3220, broken on 3.19.0
>> when boot parameter 'nosmp' is specified, again no acpi entry in
>> /proc/interrupts,  working fine on 4.0-rc6
>>
>> So obviously between 3.19 and 4.0-rc6 something got fixed here!
> Hi Jim,
> Yes, the bugfix patch should be:
> commit 1ea76fbadd66("x86/irq: Fix regression caused by commit b568b8601f05")
> 
>> The Dell laptop remains the only problem then on 4.0-rc6, there IS an
>> acpi interrupt  (but firing once apparently).
>> There isn't an option in BIOS to enable LAPIC, however, when specifying
>> 'lapic' as boot parameter I got interesting result, still not working
>> and /proc/interrups still shows XT-PIC.  Doing a diff between dmesg on
>> 3.19 and 4.0-rc6 this pops out:
>>
>> -Local APIC disabled by BIOS -- you can enable it with "lapic"
>> -APIC: disable apic facility
>> -APIC: switched to apic NOOP
>> +Local APIC disabled by BIOS -- reenabling.
>> +Found and enabled local APIC!
>>
>> +Enabling APIC mode:  Flat.  Using 0 I/O APICs
> What's the last know working kernel for Dell laptop?
> Does it work as expected with v3.19 kernel?
> Do you means this message is from plain v4.0-rc6 kernel?
> Thanks!
> Gerry
> 
>>
>> Jim
>>
> 
Last know working version on the Dell laptop is 3.16 and yes this message"

>> -Local APIC disabled by BIOS -- you can enable it with "lapic"
>> -APIC: disable apic facility
>> -APIC: switched to apic NOOP
>> +Local APIC disabled by BIOS -- reenabling.
>> +Found and enabled local APIC!

is from the v4.0-rc6 message. Full dmesg attached.

Jim.



Download attachment "dmesg-lapic_specified.gz" of type "application/x-gzip" (9807 bytes)