Messages in this thread | | | Date | Tue, 22 Jul 1997 08:42:50 -0400 (EDT) | From | "Richard B. Johnson" <> | Subject | Re: Kernel cpu selection + other platforms? |
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On Mon, 21 Jul 1997, Roland Steinbach wrote:
> Mike Jagdis wrote: > > > Why? It is pretty easy to recognise all x86 varieties (other than the > > early 486 clones) at run time and simply Do The Right Thing without > > asking the user daft questions about whether they have microcode > > bug #564 or working frozzle optimizations.
It is very easy to identify the CPU at run time but you can't do anything about what you find. It's too late. To obtain optimum performance, you need the code compiled to take advantage of a particular CPU. For instance, a '486 doesn't give a damn about longword alignment. A pentium does. You can't realign code at run time. It is possible to align buffers at run time, but the overhead could be somewhat extreme. You can't just build a kernel for the latest and greatest CPU because some internally- locked instructions, which you really would like to use, are not supported in a '386, etc., etc.
So with Intel, we have to make a kernel which will run with anything, then rebuild the sources to take advantage of the platform's latest CPU advances.
Cheers, DJ -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Richard B. Johnson Analogic Corporation Email : rjohnson@analogic.com, johnson@analogic.com Penguin : Linux version 2.1.44 on an i586 machine (66.15 BogoMips). Warning : It's hard to stay on the trailing edge of technology. -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
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