Re: [PATCH-2] NMI trap revised (was Re: NMI errors in 2.0.30??)

Martin Mares (
Fri, 9 May 1997 14:46:58 +0200


> I have implemented the memory check.
> S.o. suggested that I should read instead of write. Read two times ...
> ah ... heh ... I remember ... processor caches ... hmmm in the next patch
> I will correct this thing :)
> nghe ... I'm just curious if it works or not (heh ... I have no way to
> test it). I suspect the memory test should be done in a cli()/sti() pair,
> because we do not want be disturbed by NMIs not generated intentionally by
> us.

Hmmm... there are numerous "design flaws" in this solution:

(1) You read even the reserved pages which could contain memory-mapped
ports doing strange things even when being read.

(2) You expect the freshly allocated temporary page to contain no parity

> Hmmm I have seen an enable_NMI or something like that in the pre-2.1.37-5
> patch. It uses the bit 3 of 0x61, but my manual state that bit 3 ena/dis
> I/O Channel Check while bit 2 ena/dis Memory Parity Check. Who is wrong ?
> Me or the pre kernel patch ?

Maybe both :-)

I'll look at it today.
Have a nice fortnight