Cyrix Patches

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Since getting my Cyrix 6x86, I have been working on a set of patches to improve support for it. I am pleased to present you with the same.

THIS IS ALPHA-TEST CODE: I have only tested it on my computer. (My 2.1.4 floppy driver crashes things, so I couldn't make boot disks for the others.)

Who might find this interesting:

People with a 6x86,
People with another, non-Intel chip (to check the detection code)

This patch:

• Detects the 6x86
• Sets up its cpuid support so Linux can detect it
• Turns on suspend-on-hlt mode so it doesn't incinerate itself
• Uses a single VSPM page to do the kernel identity mapping
• DOES NOT fix the Cyrix Bogomips problem (It doesn't happen to me! Email me if it happens to you.)
• DOES NOT support any Cyrix chips other than the 6x86 (Hmmm, no real intention to fix this. Email me why I should.)

Installation notes:

Once you have cyrix.patch, try

• patch -d /usr/src/linux -p1 < cyrix.patch.
  
• Run make config, make menuconfig or make xconfig and turn on Cyrix 6x86 support, under "General Setup". Note that you must have Pentium or PPro selected as your processor type for this option to appear.
• Make the kernel as you normally would.
• BACK UP ANYTHING VALUABLE.*
• Reboot with the new kernel.
• Email the results (what happened, not vmlinux) to plewycky@oise.utoronto.ca.

Ok, I haven't actually lost anything because of this patch, but I came pretty close. Besides, what if your drive fails next week? When was the last time you backed up?

Thanks for reading all this & trying out the patch.

PS. (How the detection works.) The detection works by making sure the chip is a Cyrix, or at least not Intel, by doing a divide and checking the flags. Only on Cyrix are the flags not altered. Then it goes and mucks with ports 0x22 and 0x23, which are reserved for the motherboard, so even if we improperly detected a Cyrix, we should be able to get away with playing with them.

UPDATE!

I've done some more work on my Cyrix 6x86 patches. They are now available in two incarnations, 2.0.22/23 and 2.1.5. Apart from that, I didn't change much, although you can now deallocate VSPM pages if you want to. I also modified the configure option, so you don't have to have Pentium or PPro set anymore.

NOTE: If you have my previous patch installed, remove it via patch -R before adding this in!

Please see my previous post (or email me) for the release notes. The two uuencoded files are cyrix.patch.gz, for 2.1.5, and cyrixold.patch.gz, for 2.0.23.

Thanks.

PS: One other thing... Was there another Cyrix patch? I didn't use to read the mailing list, so I would have missed it, but it looks as if there's another thread discussing it. Could somebody please clue me in?