[Mesa-dev] Megaradeon

[Emil Velikov]

On 16/05/14 03:03, Michel Dänzer wrote:
> On 15.05.2014 21:13, Emil Velikov wrote:
> 
>>> On 15.05.2014 10:58, Marek Olšák wrote:
>>>> Hi everybody,
>>>>
>>>> Some distros seem to care about the size of Mesa, so I came up with
>>>> this little patch.
>>>>
>>>> It puts r600g and radeonsi into r300_dri.so. The result is one shared
>>>> library which contains all three drivers. Also, all driver loaders in
>>>> Mesa should now always load the r300 driver instead of r600 and
>>>> radeonsi.
>>>>
>>>> The radeon winsys is created first, which then creates the correct
>>>> screen (r300, r600, or radeonsi) according to the PCI ID.
>>>>
>>>> The libGL loader has actually been ignoring the driver name from the X
>>>> server for quite some time, so nothing needs to be done for this
>>>> outside of Mesa.
>>>>
>>>> This is for *_dri.so only, the other targets are still separate and
>>>> probably broken with this patch. (VDPAU, XvMC, egl-gallium, OpenCL?)
>>>>
>>>> What's missing:
>>>> - do the same for the other targets/APIs
>>>> - remove r600 and radeonsi targets and clean up the build system
>>>>
>>>> Original files without debugging symbols:
>>>>   5.9MB r300_dri.so
>>>>   6.5MB r600_dri.so
>>>>   5.7MB radeonsi_dri.so
>>>> Megaradeon:
>>>>   7.0MB r300_dri.so (all 3 drivers)
>>>>
>>>> If somebody who cares about the size of Mesa wants to finish this up,
>>>> the patch is attached. This is only a proof that it's not really
>>>> difficult. What remains is mostly just build system work.
>>>
>>> FWIW, I think it would be cleaner to use a new name instead of reusing
>>> any existing name.
>>>
>>>
>> FWIW currently only radeon drivers are split in such a way - freedreno and
>> nouveau have been using such separation at winsys level as far back as I can
>> remember.
> 
> r300 and r600 didn't share much if any code when they were classic Mesa
> drivers.
> 
One does not need to share code to use the approach :) Although it makes sense
more sense if they do.

> 
>> Any thoughts about backwards compatibility - old loader (libGL, libEGL etc.)
>> and new r300_dri? Example: X/ddx requests r600_dri, whereas it does not exist.
>>
>> If the above is not a concern, then a nicer approach would be to rename the
>> classic radeon to r100/radeon-vieux, and use radeon for the gallium driver
>> (idea borrowed from nouveau). Otherwise we will need to create hardlink for
>> each gallium driver.
> 
> Xorg has a loader as well, so I think there's no sane way around keeping
> the existing names as links.
> 
Kind of deliberately mentioned the option as I've already tried it and it
seems to work nicely with nouveau + swrast. AFAIK the classic megadriver uses
the same approach.


On 15/05/14 14:55, Marek Olšák wrote:
> Yeah, hardlinks might be needed to keep old libGL working.

and

On 15/05/14 14:02, Christian König wrote:
> The whole approach sounds like a good idea to me.
>
> Renaming the old driver would probably work (with a little confusion on the
> users side of course), but our marketing recently suggested a different name.
> We should discuss that internally at AMD first.
>
> Christian.

IMHO those two slightly diverge. One might want to establish if backwards
compatibility is an issue and then take a look at the possible names.

I would personally opt for compatibility.

Emil