I generally don't compile the kernel with any optimizations except
"-O -pipe". I never have a problem - and I don't have any performance
differences that have been noticable.
Tom Veldhouse
[EMAIL PROTECTED]
----- Original Message -----
From: "Mark Powell" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, December 11, 2000 9:24 AM
Subject: Different gcc optimisations cause IP packet CRC problems
> Hi,
> On a PIII 600E, compiling a week old 4.2S kernel with the following
> options:
>
> -O2 -fomit-frame-pointer -mpentium -march=pentium -pipe
>
> Cause the kernel to produce TCP CRC errors when talking to certain IP
> addresses. It generally seemed to get the 2nd octet of the CRC out by one
> i.e. 0xb9f7 became 0xbaf7 etc.
> I originally did this, because I was using this fastish machine to
> remake world for another P166 machine. I forgot to change it back and
> accidentally recompiled it's own kernel with the above settings.
> This problem was fixed by simply changing the gcc optimisation to the
> correct CPU type:
>
> -O2 -fomit-frame-pointer -mpentiumpro -march=pentiumpro -pipe
>
> However, shouldn't the PIII be backwards compatible with any Pentium code?
> Or are there some incorrect assumptions made in the CRC generation code?
> Cheers.
>
> BTW Where in the source is the CRC generated?
>
> Mark Powell - UNIX System Administrator - The University of Salford
> Academic Information Services, Clifford Whitworth Building,
> Salford University, Manchester, M5 4WT, UK.
> Tel: +44 161 295 5936 Fax: +44 161 295 5888 www.pgp.com for PGP key
>
>
>
>
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