concerning libva-1.7.2-1 backport

[James Cowgill]

On 05/09/16 17:52, Nicholas D Steeves wrote:
> On Mon, Sep 05, 2016 at 04:58:41PM +0100, James Cowgill wrote:
>> Hi,
>>
>> On 05/09/16 16:39, Nicholas Steeves wrote:
>>> On 5 September 2016 at 11:03, James Cowgill <jcowgill at debian.org> wrote:
>>>> On 05/09/16 15:41, Nicholas D Steeves wrote:
>>>>> Hi Sebastian,
>>>>>
>>>>> When backporting libva-1.7.2-1 today, it builds against and depends on
>>>>> libdrm-2.4.58-2 instead of 2.4.70-1~bpo8+1.  Intel-vaapi-driver
>>>>> correctly builds and depends on libdrm-2.4.70-1~bpo8+1.  Is it really
>>>>> ok?  Shouldn't the two build against and require the same libdrm
>>>>> version? eg, intel-vaapi-driver/debian/control: libdrm-dev (>= 2.4.60)
>>>>
>>>> libdrm 2.4.70 gets pulled in when intel-vaapi-driver is built because
>>>> intel-vaapi-driver depends on intel-gpu-tools from backports, which in
>>>> turn depends on a newer libdrm.
>>>>
>>>> I think I said this to you before: this is not a problem because the
>>>> versions of libdrm at runtime will always be the same everywhere and
>>>> intel-vaapi-driver does not seem to do anything different (as far as I'm
>>>> aware) if built against a more recent version of libdrm.
>>>>
>>>> James
>>>>
>>>
>>> Hi James,
>>>
>>> I understand how the intel-vaapi-driver dependencies work, and which packages end up installed at runtime.  My concern is specifically:
>>>
>>> A.
>>> 1. build libva (built with old_libdrm)
>>> 2. build intel-vaapi-driver (built with new_libdrm and with (libva built with old_libdrm))
>>> 3. install intel-vaapi-driver (install new_libdrm and (libva built with old_libdrm))
>>>
>>> vs
>>>
>>> B.
>>> 1. build libva (built with with newdrm)
>>> 2. build intel-vaapi-driver (built with new_libdrm and with (libva built with new_libdrm))
>>> 3. install intel-vaapi-driver (install new_libdrm and (libva built with new_libdrm))
>>>
>>> Are (A) and (B) really equivalent?  I understand that the installed package versions are the same, but
>> A2 != B2 makes me think that they're not equivalent.  That's what I'm
>> wondering :-)
>>
>> From your breakdown, A and B are equivalent iff:
>>  libva built with old_libdrm
>>   and
>>  libva built with new_libdrm
>> are equivalent.
>>
>> I believe this is true on the basis that libav doesn't do anything
>> special if built against a newer libdrm. The final libav binaries should
>> pretty much be identical.
>>
>> James
>>
> 
> Hi James,
> 
> Sweet! :-)  Thank you for taking the time to clear up this point.  Can we depend on upstream updating libav/configure.ac if ever this changes?

I think you'll have to ask libav upstream about that, but I hope the
answer is yes!

James

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