Re: the >1Tb block issue

[Michael Tokarev <mjt@tls.msk.ru>]

18.05.2010 21:38, Avi Kivity wrote:

>> [Qemu-devel] [PATCH +stable] block: don't attempt to merge overlapping
>> requests
>>
>> quick tests shows it works correctly so far.
>> At least it went further than before, not
>> stopping at the "usual" sector 3145727872.
>>
>> Hmm. Ide has no queue, hence no mergeing,
>> that's why it does not occur with ide,
>> right? :)
>
> Yes.

I tried multiple times to reproduce it with if=scsi
(queue_depth=16 for the sym53c8xx driver).  I can't.
JFYI.. ;)

(And this kinda explains why the bug does not occur
when run under strace; which also indicates that it
isn't necessary easy to trigger it, too).

>> Interesting...
>
> Yes. Why would Linux post overlapping requests? makes 0xffffffff00000000
> sense.

It's mkfs.  Not sure why, but yes, maybe it's a guest
bug after all.  Note that I'm running 64bit kernel on
the guest (2.6.32.9-amd64).

Note also that it's not as on the original bugreport -
there, the sector# is apparently different:
http://sourceforge.net/tracker/?func=detail&aid=2933400&group_id=180599&atid=893831

> There may be a guest bug in here too. Christoph?

/mjt