On 18-02-08 22:04, Rene Herman wrote:
On 18-02-08 21:43, H. Peter Anvin wrote:
Rene Herman wrote:
Now with respect to the original pre port 80 "jmp $+2" I/O delay
(which the Pentium obsoleted) I suppose it'll probably be okay even
without fixing that specifically but do note such -- it's a vital
part of the problem.
Sorry, that paragraph didn't parse for me.
I mean that before the linux kernel used a port 0x80 write as an I/O
delay it used a short jump (two in a row actually...) as such and this
was at the time that it actually ran on the old legacy stuff that is of
most concern here.
No, if I'm not mistaken, those two jumps are actually what the udelay()
_Now_, if I'm ...
is going to do anyway as part of delay_loop() at that early stage so
that even before loops_per_jiffy calibration, I believe we should still
be okay.
Yes, it's a bit of a "well, hrrm" thing, but, well... loops_per_jiffy
can be initialised a bit more conservatively then today as well (and as
discussed earlier, possibly per CPU family) but I believe it's actually
sort of fine not too worry much about it...
Rene.
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