Well, I'll admit that I've had a really hard time following this whole
discussion.  You could come over and we could actually spend a couple
of hours discussing this if you like.

  Nate


On Thu, Sep 25, 2008 at 1:41 PM,  <[EMAIL PROTECTED]> wrote:
> There are multiple issues here, and I think they're getting mixed together.
> Unfortunately this is complex enough that it's hard to explain in an email.
> I'll try to explain it more fully sometime soon, hopefully with something more
> expressive, although I don't know how much time I'll have before early next
> week. Ideally we'd talk about this in person with a whiteboard, but that's
> obviously not possible.
>
> Gabe
>
> Quoting Steve Reinhardt <[EMAIL PROTECTED]>:
>
>> I think maybe I got misled by the earlier discussion about keeping a pointer
>> to the macroop in the thread context.  Correct me if I'm wrong, but the
>> issue now isn't really about that pointer.  The issue is that when a series
>> of microops from a single macroop reaches the head of the ROB, and one of
>> those interior microops is marked as faulting, do I flush the preceding
>> non-faulting microops from the same macroop before invoking the fault
>> handler or not?
>>
>> If this is the problem, then it only applies to faults and not to
>> interrupts, since as we've discussed you'll never get an interrupt in the
>> middle of a macroop.
>>
>> You're saying that outside of this funky optimization for string moves (and
>> maybe other instructions) then it's OK to always flush the microops.  I
>> agree.
>>
>> Thinking about it a little more, I'd bet it's always OK to flush the
>> microops... looking at the string move case, you really don't care about
>> restarting the macroop that faults (since that macroop represents only the
>> last iteration of the REP)... what you really want to do is retry the entire
>> macroop with the "safe" version of the microcode before you invoke the
>> actual fault handler.
>>
>> So is it that simple?  Or am I missing something?
>>
>> Steve
>>
>
>
>
>
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