On Saturday 19 March 2005 05:05, Attila Kinali wrote: > On Fri, 18 Mar 2005 14:39:04 -0500 > > Daniel Phillips <[EMAIL PROTECTED]> wrote: > > On Friday 18 March 2005 05:16, Attila Kinali wrote: > > > On Thu, 17 Mar 2005 21:53:04 -0500 > > > IMHO there needs to be at least a check whether the > > > send commands can do anything harmfull. I also see > > > now that Timothy is right, a bit of hw support for this > > > kind of stuff will help. > > > > What exactly do you propose to check for? > > Anything that might lead to unexpected, hardware or > software damaging behaviour. Like overwriting state registers, > changing frequency/resolution settings... > Anything you do not want to be changed by some program that > might be running on your machine.
None of the commands you mentioned will be available via command DMA, they will be performed via PIO. As Timothy has said, let's just not introduce any indirect DMA command that can crash the card. > > > > - PIO is only available to privileged tasks, normally only > > > > the kernel driver. > > > > > > How is this differentiation going to provide security ? > > > If i can DMA to any memory location on the card, then i > > > can also overwrite the PIO registers with indirect DMA. > > > Or do i miss something ? > > > > The PIO registers aren't in card memory, they are on the FPGA. > > Hmm? Looks like i missunderstand the term PIO. Can you clarify > it for me please ? "Programmed IO". The CPU transfers data to/from a peripheral device by writing/reading an IO register (which can be an IO space port or a memory mapped port). As opposed to DMA, "Direct Memory Access", where a peripheral bypasses the CPU and accesses memory directly. Regards, Daniel _______________________________________________ Open-graphics mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
