Jerome Glisse has sent a new patch to the other DRI developers that adds a command checker for the ATI R600/700 series graphics processors. The command stream (CS) checker ensures that no commands are attempting to access the GPU in a way that it shouldn't, such as accessing memory out of its resource size, which without the safety mechanism could be exploited by those with malicious intentions. Jerome still has a few items on his TODO list for this R600/700 series command stream checker, but it's now published for review and could potentially be ready in time for the Linux 2.6.34 kernel
This patch is quite large and can be found here
along with his mailing list message
. The command stream checker isn't something for end-users to get excited over, but is just for fending off possible GPU problems (security or simply a troubled command).