[Intel-gfx] [RFC 00/15] Selectable platform support

[Tvrtko Ursulin]

On 08/02/2018 13:26, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2018-02-08 13:05:51)
>> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>>
>> For Joonas basically. :)
>>
>> Rough goal - add Kconfig options to turn off supported platforms and count on
>> compiler DCE to make the driver smaller.
>>
>> Tested as so much that it boots and renders on Skylake with all platforms/gens
>> older than Gen8 turned off.
>>
>>     text    data     bss     dec     hex filename
>> 1502847   54223    2888 1559958  17cd96 i915.ko.original
>> 1375647   51939    2888 1430474  15d3ca i915.ko.gen8+
>>
>> So only ~124kiB saving. Or ~8.5%. Perhaps once GCC LTO support lands it would be
>> better than this?
> 
> Did you get to the point where the compiler was complaining about unused
> functions?

No, but on a random check it seems that it is removing some. For 
instance i965_emit_bb_start and i830_emit_bb_start are not in my build.

Doesn't mean I haven't made some other mistake which is preventing more 
savings.

>> Starts with smaller patches to show the idea step by step on Gen2, then proceeds
>> in larger chunks, to finish with some invasive Coccinelle works to enable the
>> last few kilo-bytes of savings.
> 
> So, if we want to support this, how do we test it?
> 
> Do a per-platform build and check modinfo for pci ids?
> 
> Limit the CI builds to be per-platform and check they work?

Extensively. :) Which will probably be a problem. PCI ids is not enough, 
I think it would actually need functional testing so a growth of number 
of builds we would need to test.

Regards,

Tvrtko