FYI: Merge in progress...S2735

Eric W. Biederman ebiederman at
Fri Oct 22 21:46:00 CEST 2004

YhLu <YhLu at> writes:

> Eric,
> About S2735, in auto.c
> How to change 
> #include "cpu/p6/apic_timer.c"
> Amd version is
> #include "cpu/amd/model_fxx/apic_timer.c"
> I can not find other apic_timer.c in src/cpu

This is a good question.  

The simple answer is that an apic timer based delay was
an extremely clever hack on the Opteron.  Possibly too clever.

Intel cpus to my knowledge to not have a fixed front side bus.
And even where they effectively do I don't know how if that
even relates to the speed at which the apic timer runs.

So for the moment I have reverted the e7501 to it's historical
tsc, timer2 and inb(0x80) based delays.  

I am willing to revist this.  But if we change this I want
it to be because we are doing something better.

In practice even the Opteron code should change and have the
apic_timer code included in the cpu/socket directory.

Timers are one of those things we have always needed but there
does not seem to be a good method of making them work.


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