Re: MMU faults while trying to install 1.5

["Frank Wille" <frank%phoenix.owl.de@localhost>]

Ignatios Souvatzis wrote:

> > article in the Amiga Format magazine. This mentioned some kind of bug
> > in the 68060. They also had a program called NoBypass which apparently
> > fixed this bug. Now I'm able to run the 68060 at almost full speed.
> > Could NetBSD be affected in my case by the same bug ? The assembler
> > program can be found on AmiNet in the 68060fix.lha archive.
> 
> Hm. I'll check what this about.

The bug will only occur after a very stupid combination of read
and write instructions, while reading the same memory address
twice, AFAIR. No assembler programmer and most good compilers will
never create such a sequence, so it's not very likely that this is
the reason of John's MMU problems, IMHO.

I had this bug though, one year ago, while porting Quake for
AmigaOS/68k with the vbcc compiler. It happened on both, 060 Rev.1
and 060 Rev.5 CPUs (CSPPC in both cases), although Motorola stated
that only Rev.1 CPUs could be affected. Changing bit 5 in the PCR
fixed it.

--
   _  Frank Wille (frank%phoenix.owl.de@localhost)
_ //  http://home.owl.de/~frank/
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