Re: [Qemu-devel] [PATCH for 1.4] block/vpc: Fix size calculation

[Stefan Weil]

Am 11.02.2013 22:20, schrieb Jeff Cody:
> On Mon, Feb 11, 2013 at 03:14:36PM -0600, Anthony Liguori wrote:
>> Paolo Bonzini <address@hidden> writes:
>>
>>> Il 11/02/2013 21:13, Anthony Liguori ha scritto:
>>>> Applied.  Thanks.
>>>>
>>>> Regards,
>>>>
>>>> Anthony Liguori
>>> I guess this was a mistake, please revert.
>> No, it wasn't.  The patch was reviewed and tested.  What's the problem.
>> It's proposed for 1.4 so it's now or never.
>>
>> I saw some discussion about improving the detection for the different
>> varients of VHD...
>>
>> I don't mind reverting it, but just want to understand what the issue
>> is.
>>
> Hi Anthony,
>
> It was tested, the problem is that this will break existing support
> for Virtual PC VHD files under certain conditions (most likely
> exporting from qemu to VPC, but I don't know if we could guarantee
> that is the only way).
>
>
> Jeff

Hi Jeff,

exporting from QEMU to VPCwill work because QEMU uses
images where real size = CHS size, so those images work
no matter whether the patch was applied or not.

See my separate mail for more reasoning.

I see no way how the patch could break a realistic test scenario,
but I know such scenarios which are broken without the patch.


Stefan