All the other cool drivers support it, and we could on gen4+ as well.
Can't we sufficiently approximate it on gen2/3 with the 4x4 tap texture filter?
No, we can't issue that many texture lookups from within the fragment shader. Multi-pass accumulation buffer... Dream on.
Daniel was referring to MAPFILTER_4x4_ and 3DSTATE_FILTER_COEFFICIENTS_4X4. Seems like it will be easiest to prototype on gen3 once again.
Gen2 DevMGM has a 4x4 filter too, but with slightly different instructions.