New 745x errata

Giuliano Pochini pochini at
Fri Nov 14 21:40:53 EST 2003

On 13-Nov-2003 Adrian Cox wrote:
> Since October there are new errata on Motorola's website for the 745x
> family processors. The following patch against linuxppc-2.4-devel
> contains workarounds to two problems:
> 1) The BTIC doesn't work reliably: it can cause execution of corrupted
> instructions. (This is listed in the errata for the 7450 and 7457, but
> not for the 7455. I'll only believe that the 7455 escaped this bug if I
> hear confirmation out of Motorola.)

Did you try to ask them about it ?

> 2) dcbt to protected addresses can cause spurious bus cycles. This could
> potentially be exploited from userspace to lock up hardware.

Hm, a 1-cycle window this is very small.  Anyway, if dc* instructions are
used inside the kernel, we could keep them disabled in userspace only.


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