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    SubjectRe: Cyrix patch : Proposal?

    A very good post. I would assume that you approve of minor patching so
    that cpuinfo displays the correct information?

    On Wed, 5 Nov 1997, Andre Derrick Balsa wrote:

    > Hello,
    >
    > Teunis, I would *not* want to see the (fixed) 2.1.39 Cyrix patch go into
    > the kernel source, as it stands now.
    >
    > I have a simple technical reason, and a more "philosophical" reason for
    > this.
    >
    > Technical: no performance gains
    > ==========
    >
    > The main performance improvement that can be had by adapting Linux
    > operation to a 6x86 processor is the correct setup of the ARR registers.
    > This can bring a 30-50% CPU/video memory bandwidth improvement.
    >
    > The 2.1.39 patch does *not* set the ARRs, because this would imply the
    > detection of the linear frame buffer address, which changes from system
    > to system.
    >
    > The other performance features bring a *measured* performance
    > improvement of less than 0.5%. This is insignificant IMHO.
    >
    > Philosophical: kernel pollution vs. user-space utility
    > ==============
    >
    > Everything (nearly) the patch does can be done in user-space using the
    > set6x86 GPLed utility written by Koen Gadeyne. You don't have to
    > recompile your kernel everytime a 6x86 feature needs to be tested or
    > changed. And set6x86 allows setting the ARRs.
    >
    > The only thing set6x86 cannot do is implement the 6x86 VSPM feature,
    > which only works in some 6x86 revisions, has been dropped in the new
    > 6x86MX and does not provide any measurable performance improvement.
    >
    > So I would prefer to keep the kernel source as clean as possible,
    > without adding every possible trick or gadget (this also applies to
    > other tricks and gadgets that unfortunately have gone into the kernel
    > source, sometimes causing strange side-effects).
    >
    > In some cases a patch is needed, but the 2.1.39 Cyrix patch is not.
    >
    > OTOH it's an excellent patch and I thank Mike Jagdis (the original
    > author) for it. It's a clean patch and the accompanying documentation is
    > of the highest quality (quite exceptional when it comes to kernel
    > patches).
    >
    > I will give you another example of something that should be set using a
    > user-space utility: IDE driver parameters. We have hdparm thankfully,
    > but imagine what would have happened if M. Lord had decided to make all
    > the hdparm options kernel compilation option? I guess he made a good
    > decision, and I propose we follow his example when it comes to the cyrix
    > 2.1.39 patch.
    >
    > Cheers,
    >
    > ========================================================
    > Andrew D. Balsa
    > Please remove the .nospam suffix in the Reply-to address
    > My true email address is andrewbalsa@usa.net
    > ========================================================
    >


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