On Thu, Mar 30, 2006 at 11:49:22AM +0100, Nigel Stephens wrote: > They're variable, but not very variable: the PID->ASID mapping will only > change when the ASIDs roll over and the ASID gets reallocated to a > different process, which will only happen after another 256 processes > have been created. But in that case your watched process will have to be > allocated a new ASID before it can run again. So you could, perhaps, > modify the TLB management code to clear the Watch registers whenever an > ASID belong to a process with watchpoints is recycled, and then > reprogram the Watch registers when such a process is allocated a new > ASID. Alternatively you could maintain pre-process copies of the Watch > registers, and context switch them along with other per-process register > state -- though that is adding context switch overhead to processes > which don't use watchpoints, and might not be popular with the maintainer. That's not quite true; the kernel also uses the ASID as a way to flush a context from the TLB very quickly. Ralf
