Comment 20 for bug 798049

On 06/24/2011 11:08 PM, Anders Kaseorg wrote:
> In comment 13:
>> Yes, we have to upload a new mesa and set versioned breaks.
>
> Assuming that was a reply to comment 12, that wasn’t what I was worried
> about. Even when a new mesa is uploaded with versioned breaks, it will
> still have the problem I described:
>
> “Hmm, it’s still not possible for me to install nvidia-current on x86_64
> but configure it to not be used, because although x86_64-linux-
> gnu_GL.conf can be overridden by the mesa version, there is no mesa
> version of i386-linux-gnu_GL.conf, and nvidia’s i386-linux-gnu_GL.conf
> includes the 64-bit libraries too.”

fglrx and nvidia install a fake alternative in addition to the one for
your architecture, which is meant to override the second alternative
provided by multi-arch mesa (e.g. by i386 mesa if you're using adm64).
This means that you should only configure the alternative for your arch
for now as apt, by default, is not multi-arch enabled yet and therefore
you can't install i386 mesa using apt yet (again with the default settings).

>> I know that removing all non multiarch gl_conf alternatives may not
>> seems exactly a good idea but I've noticed that installing a multiarch
>> alternative beside a non multiarch one would fail because they point
>> to the same files (despite using different links).
>
> My suggestion was not that you should install the multiarch alternative
> beside the non-multiarch alternative pointing to the same files. It was
> “It should only delete the [non-multiarch alternative] belonging to
> itself.” This is what libgl1-mesa-glx.postinst does, and it’s what I
> did in my patch:
>

Yes, I didn't misunderstand what you said. I tested this on a system
with fglrx, nvidia-current and nvidia-173 installed at the same time. So
if, for example, you installed nvidia-current you would remove the old
alternative installed by the old nvidia-current but then the new
alternative would conflict with the old alternative provided by
nvidia-173, and so on. Unfortunately I don't have access to my
workstation to show you the exact error but I'm available to do so next
week when I'm back home, if you're interested.

--
Alberto Milone
Sustaining Engineer (system)
Premium Engagements Team
Canonical OEM Services