Re: [RFC Patch 6/9] Use virtual debug registers in process/threadhandling code

From: Roland McGrath
Date: Fri Oct 17 2008 - 20:09:22 EST

> There's a problem with moving the switch_to_thread_hw_breakpoint() call
> before current is updated. [...]

I got this. I'm just saying let's look for ways to do this better.

Hmm. The 64-bit version of __switch_to does the current change much
earlier, before __switch_to_xtra and math_state_restore. I wonder if the
32-bit version could change to match. I can't see what in __switch_to_xtra
would care either way, though I may be overlooking something. Ingo?

If this does not change, then __switch_to_xtra can pass prev,next to
switch_hw_breakpoint. You can always do some slightly different
bookkeeping in there to know that prev->next is the switch happening,
so if there is a hit when current still == prev you can filter it out.

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