Re: [Qemu-devel] 1.1.1 -> 1.1.2 migrate /managedsave issue

[Juan Quintela]

Doug Goldstein <address@hidden> wrote:
> On Sun, Nov 4, 2012 at 3:51 PM, Anthony Liguori <address@hidden> wrote:
>>>
>>> Seems reasonable.  Doug, please verify to see if it's the same issue or
>>> another one.
>>>
>>> Juan, how can we fix this?  It's clear that the option ROM size has to
>>> be fixed and not change whenever the blob is updated.  This will fix it
>>> for future releases.  But what to do about the ones in the field?
>>
>> This is not a problem upstream because we don't alter the ROMs.  If we
>> did, we would keep the old ROMs around and set the romfile property in
>> the compatible machine.
>>
>> This is what distros that are shipping ROMs outside of QEMU ought to
>> do.  It's a bug to unconditionally change the ROMs (in a guest visible
>> way) without adding compatibility support.
>>
>> Regards,
>>
>> Anthony Liguori
>>
>
> Anthony,
>
> Gerd updated seabios on August 7th and before that on April 17. The
> default VGA ROM size also changed in recent releases. There are no old
> versions of the ROMs included once these updates are performed so a
> user building a new version from source will hit this problem. Juan
> Quintela even mentioned that he has been bit by this issue and had to
> use gdb to track it down as did Philipp that responded earlier in the
> thread. The patch is a simple fprintf() which would have saved at
> least 3 users the effort of tracking down an issue with gdb. So I urge
> you to reconsider.

I hit this problem.  But it was a bug, the problem was to detect it.

The problem was doing migration to an old version, we now "round" the
RAM amount to a multiple of 8k.  If your old ram memory was mulitple of
4k, you get this prolbem with migration.

And it only prints "migration failed".  Printing a message telling that:
memory size of %foo is %d and expected %d would have make error trivial
to found.

Later, Juan.

PD.  Problem was really a bit more complex than this, this is a
     simplification.