[Cbe-oss-dev] SPE program loading through DMA

[Arnd Bergmann]

On Thursday 30 October 2008, Yury Serdyuk wrote:
> >Note that the proxy DMA facility only works as long as the SPU is executing
> >code in spe_context_run. You have to start the SPU first in order to
> >use it. 
> >
> Nevertheless,  why  can I do DMA transferring well on PS3 without SPU 
> running but not on QS22 ?

It's just coincidence. If all the pages are in memory and the context
has been loaded into the SPU, a proxy DMA may complete even if the
SPU is not currently running, but there is no way you can rely on that.

On QS22, we switch of the master run control bit of the SPU to make sure
that nobody can rely on the undefined behaviour. On the PS3, this bit
is not accessible due to a hypervisor restriction.

	Arnd <><