Messages in this thread |  | | | Date | Mon, 10 Nov 1997 10:07:56 +0000 (GMT/BST) | | From | Mike Jagdis <> | | Subject | Re: Cyrix patch : Proposal? |
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On Thu, 6 Nov 1997, Brian Gerst wrote:
> If the patch were stripped down to just do the cpu detection, and leave > the configuration up to set6x86 (except for enabling cpuid), would you > object to that?
There seems little point. The extra code required to set up CPU features is not particularly great. Furthermore changing performance settings later when you have user processes up and running means that other initializations which require repeatability, such as udelay, are silently broken. The effects of such damage tends to be obscure and insidious. Personally I prefer the overhead up front where we can get it out of the way rather than the risk of weird things happening to _some_ of the people _some_ of the time.
Incidentally, the reason why all those wierd features are config options is simply for testing. Ultimately the options should be removed completely and the code should just do what is right for the processor in use.
VSPM can actually be done outside the kernel - but you would have to have set up traditional page tables to get far enough to do it. The circumstances under which VSPM would show a gain simply because of TLB effects are probably not easily tested with any of the common performance measuring tools around. You do however save a few pages of memory which would otherwise have gone to kernel page tables :-). Since only the 6x86-none-MX has VSPM it probably _should_ be optional, if it is included at all.
Mike
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