Re: [Qemu-devel] [PATCH v2] virtio-blk: add default serial id

[Dave Young]

On 10/05/2012 04:14 PM, Stefan Hajnoczi wrote:

> On Sun, Sep 23, 2012 at 10:37:09AM +0800, Dave Young wrote:
>> For the serial number decreasing issue, I think there's only these two ways 
>> to
>> select, there's no ideal way to resolve this issue.
>> My use case for this is for the kdump kernel to find proper disks,
>> after 1st kernel crashing 2nd kernel need find right disk to dump vmcore.
>> In this case v1 and v2 aproaches are both find to me.
>>
>> From my point of view, patch v1 is better though, I think unpluging 100000 is
>> not a sane use case. It's not likely to happen.
> 
> I'm not sure auto-assigning serial numbers is a good idea.  The guest can use
> the serial number in /etc/fstab or other places where it expects the serial
> number to be persistent.
> 
> Your patch does not provide persistent serial numbers, so a change to the QEMU
> invocation could result in different serial numbers.  The guest will get
> confused or perhaps refuse to boot.


Yes, it introduce confusion, but in this way at least the serial number
can be persistent across guest reboot. Traditionally ide disks use this
way as well, such as QEMU_HARDISK_00001, I think guest should not use
this in /etc/fstab.

> 
> I'd prefer if we don't expose a temporary serial number at all in order to
> avoid issues like this.
> 
> Stefan



-- 
Thanks
Dave