still data corruption with 5.1-R on Intel Pentium 4

[Anthony Ginepro]

> There have been threads about data corruption in RAM on P4 and other
> i386 machines on this list.  I also observed the problem, on my laptop
> with 5.0-R.  It seemed to go away with 5.1-R, on the laptop.
> 
> Recently I upgraded my home PC which is a P4 2.0A from 4.8-R to 5.1-R. 
> No problems at first.
> 
> Until I ran "portsdb -Uu".  I got a couple mysterious SIG4 and SIG11.
> Just to be sure I rebooted and tried again, same result.  I rebooted
> another time, this time with ACPI disabled, and tried again, still the
> same.
> 
> Then I rebuilt my kernel with options DISABLE_PSE and DISABLE_PG_G, as
> suggested by Terry in the old threads: Bingo, everything is fine now, no
> more SIG4 or SIG11 during portsdb -Uu.
> 
> It seems the workarounds that we have in 5.1-R are not effective enough.
> What do you think?

I'm having some SIG4 too when doing the massive operation "portsdb -Uu".

I don't mind too much because it's usually only two make process which die
however I would like to know if DISABLE_PSE and DISABLE_PG_G impacts 
performance or not and if it's specific to BSD.

I tried lately rebuilding world and kernel with CPU_TYPE=p3 in order to be
sure it was not due to gcc over-optimizing for p4, we will see.

Anthony.