Re: raw disks no longer work in latest kvm (kvm-88 was fine)

[Avi Kivity <avi@redhat.com>]

On 05/23/2010 05:07 PM, Antoine Martin wrote:
> On 05/23/2010 06:57 PM, Avi Kivity wrote:
>> On 05/23/2010 11:53 AM, Antoine Martin wrote:
>>> I'm not: 64-bit host and 64-bit guest.
>>> Just to be sure, I've tested that patch and still no joy:
>>>   /dev/vdc: read failed after 0 of 512 at 0: Input/output error
>>>   /dev/vdc: read failed after 0 of 512 at 0: Input/output error
>>>   /dev/vdc: read failed after 0 of 2048 at 0: Input/output error
>>> pread is still broken on this big raw disk.
>>>
>>
>> Can you summarize your environment and reproducer again?  The thread 
>> is so long it is difficult to understand exactly what you are testing.
>>
> Sure thing:
>
> Description of the problem:
> A guest tries to mount a large raw partition (1.5TB /dev/sda9 in my 
> case), this fails with pread enabled, works with it disabled.

Did you mean: preadv?

>
> What has been tested:
> Host has had 2.6.31.x and now 2.6.34 - with no improvement.
> Guest has had numerous kernel versions and patches applied for testing 
> (from 2.6.31.x to 2.6.34) - none made any difference. (although the 
> recent patch stopped the large partition from getting corrupted by the 
> merged requests bug.. yay!)
> It was once thought that glibc needed to be rebuilt against newer 
> kernel headers, done that too, and rebuilt qemu-kvm afterwards. (was 
> 2.6.28 then 2.6.31 and now 2.6.33)
>
> What has been reported: straces, kernel error messages as above.
> Here is the qemu command line (sanitized - removed the virtual disks 
> which work fine and network config):
> qemu -clock dynticks -m 256 -L ./ -kernel ./bzImage-2.6.34-aio -append 
> "root=/dev/vda" -nographic -drive file=/dev/sda9,if=virtio,cache=none
>
> Let me know if you need any other details. I can also arrange ssh 
> access to the system if needed.

And: 64-bit host kernel, 64-bit host userspace, yes?

Does aio=native help?  How about if=ide?

-- 
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