Alex Deucher wrote:
> On 12/24/05, Dave Jones <davej@...> wrote:
>>On Fri, Dec 23, 2005 at 11:20:34PM +0000, Dave Airlie wrote:
>> > > Anyhow, I was wanting to volunteer my services and my Radeon Xpress 200M for development work on this project. I have some kernel hacking/driver development experience, but that was on a device with open specifications, so I wanted to ask the following questions:
>> > > 1) What do we currently know about these chipsets?
>> > They have no on-board RAM and are PCI Express
>>I'm not entirely sure that's correct. Santa brought me a laptop
>>which gives me the option of using the onboard video ram, system ram,
>>or even both. I've not had chance to play with it much yet though.
> Some of the new XPRESS chips have mixed on-board/system
> configurations. There are supposedly desktop versions with mixed ram
> types as well.
on the xpress chips, it's called sideport. It can apparently do
local/system ram accesses interleaved, though I've no idea how it works
(maybe per-tile access, half the tiles local half not?). The other
possible modes (i.e. uma only, sideport mem only, or sideport + uma but
not interleaved) look simpler.
On the desktop chips (at least for the "old" 3-letter Xxyz chips) it's
called hypermemory. As far as I can tell though those chips can't do
interleaved accesses, and I don't think there's anything different to
the non-hypermemory cards whatsoever (except they have less ram on a
half-as wide bus). At least all r300 based chips should be able to
render to system memory directly already.