[Qemu-devel] Sporadic AHCI boot failures

[Qemu-devel] Sporadic AHCI boot failures

[Jan Kiszka]

Hi,

I'm running a Win7 VM over AHCI, rebooting quite frequently. Depending
on host system load, I'm facing a lot of sporadic boot failures (disk
not found), obviously in SeaBIOS. Could it be that some timeout in the
init code bites us here? AHCI_LINK_TIMEOUT or AHCI_RESET_TIMEOUT? Just a
guess, I haven't debugged this yet.

Jan

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Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux

Re: [Qemu-devel] Sporadic AHCI boot failures

[Alexander Graf]

On 02.05.2012, at 20:14, Jan Kiszka <jan.kiszka@siemens.com> wrote:

> Hi,
> 
> I'm running a Win7 VM over AHCI, rebooting quite frequently. Depending
> on host system load, I'm facing a lot of sporadic boot failures (disk
> not found), obviously in SeaBIOS. Could it be that some timeout in the
> init code bites us here? AHCI_LINK_TIMEOUT or AHCI_RESET_TIMEOUT? Just a
> guess, I haven't debugged this yet.

Hm, I'd be surprised if that's the problem.

Do things work again after system_reset on the monitor? Maybe the reset function is just broken and we finish some asynchronous stuff after reset?


Alex

Re: [Qemu-devel] Sporadic AHCI boot failures

[Jan Kiszka]

On 2012-05-02 18:26, Alexander Graf wrote:
> 
> 
> On 02.05.2012, at 20:14, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> 
>> Hi,
>>
>> I'm running a Win7 VM over AHCI, rebooting quite frequently. Depending
>> on host system load, I'm facing a lot of sporadic boot failures (disk
>> not found), obviously in SeaBIOS. Could it be that some timeout in the
>> init code bites us here? AHCI_LINK_TIMEOUT or AHCI_RESET_TIMEOUT? Just a
>> guess, I haven't debugged this yet.
> 
> Hm, I'd be surprised if that's the problem.
> 
> Do things work again after system_reset on the monitor? Maybe the reset function is just broken and we finish some asynchronous stuff after reset?

The problem both occurs after power on as well as reset. Sometimes it
takes multiple system_reset calls to get the system booting.

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux

Re: [Qemu-devel] Sporadic AHCI boot failures

[Jan Kiszka]

On 2012-05-03 14:17, Jan Kiszka wrote:
> On 2012-05-02 18:26, Alexander Graf wrote:
>>
>>
>> On 02.05.2012, at 20:14, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>>
>>> Hi,
>>>
>>> I'm running a Win7 VM over AHCI, rebooting quite frequently. Depending
>>> on host system load, I'm facing a lot of sporadic boot failures (disk
>>> not found), obviously in SeaBIOS. Could it be that some timeout in the
>>> init code bites us here? AHCI_LINK_TIMEOUT or AHCI_RESET_TIMEOUT? Just a
>>> guess, I haven't debugged this yet.
>>
>> Hm, I'd be surprised if that's the problem.
>>
>> Do things work again after system_reset on the monitor? Maybe the reset function is just broken and we finish some asynchronous stuff after reset?
> 
> The problem both occurs after power on as well as reset. Sometimes it
> takes multiple system_reset calls to get the system booting.

Think I found it: There is bug in the new in-kernel PIT userspace code
that lets Seabios detect some 4..7 MHz CPU. So all the timeouts finish
way too early. This also affects IDE and possible other stuff in the
bios that depends on timeouts.

Digging into this...

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux

Re: [Qemu-devel] Sporadic AHCI boot failures

[Avi Kivity]

On 06/05/2012 10:08 PM, Jan Kiszka wrote:
>>>
>>> Do things work again after system_reset on the monitor? Maybe the reset function is just broken and we finish some asynchronous stuff after reset?
>> 
>> The problem both occurs after power on as well as reset. Sometimes it
>> takes multiple system_reset calls to get the system booting.
> 
> Think I found it: There is bug in the new in-kernel PIT userspace code
> that lets Seabios detect some 4..7 MHz CPU. So all the timeouts finish
> way too early. This also affects IDE and possible other stuff in the
> bios that depends on timeouts.
> 
> Digging into this...
> 

This is probably Yongjie Ren's problem as well.


-- 
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