Marvell and Mai Logic working towards PPC970 support?

[olegil]

Dang, I hate it when that happens. I bet someone worked REAL heard getting an angry cat into a bag...

I'm allergic to cats, so I'm _not_ gonna try to get it back in there.

Oh, you meant metaphorically? ;-)

[olegil]

Uhm, but a blade isn't a box, it's a board.

Forking out 2k USD for a motherboard with chips on it and having to fork out ANOTHER 4.5k USD just to get a box to put it in isn't THAT fun, really ;-)

If you have the box, PPC970 blades sounds excellent, though ;-)

[olegil]

The principles aren't the same either.
Marvell: supports PCI-X, need external glue logic to get AGP
Articia: supports AGP, well duh.

AGP uses only 32 bit and 66MHz clock which is single, dual, quad or octal pumped for higher bitrate.
PCI-X uses 64 bit and 133MHz clock to achieve higher bitrate. At the very least you'll end up with higher latency because of the MPx/60x/DDR to PCI-X to AGP conversion in two steps.

Please tell me how "connecting some pins together" and "converting from 32 bit 66MHz x 1/2/4/8 to 64 bit 133MHz x 1" will be the same? ;-)

[olegil]

64bit? You sure about that?
Please try to point it out in the specification:

http://www.mai.com/products/BRA660R2.0.pdf

I'm waiting.
Apart from this, Ben is right. If you have 32bit, 66MHz PCI, you just need a few control signals to have 1xAGP. 2xAGP requires double-pumping that clock yet again (effectively 32 bit, 133MHz). So if you have 133MHz and 64bit, like the Marvell controller, you could use external glue logic to tie it up to a 4xAGP device, but you would SURELY add latency compared to the solution with 2xAGP plugged right into the controller. This is because of the half buswidth but double clock rate conversion you need.