Re: 2.2.0pre1 OOPS on boot.

Theodore Y. Ts'o (tytso@mit.edu)
Thu, 31 Dec 1998 16:36:05 -0500


From: torvalds@transmeta.com (Linus Torvalds)
Date: 30 Dec 1998 02:32:43 GMT

It seems that the Cyrix chips do not do "rdtsc", even when they call
themselves 686's.

We may need to have a special case for chips without "rdtsc".

Or simply use a run-time check for rdtsc (this example is from the
/dev/random driver):

if (boot_cpu_data.x86_capability & X86_FEATURE_TSC) {
__u32 high;
__asm__(".byte 0x0f,0x31"
:"=a" (time), "=d" (high));
...

Now, if the Cyrix chips are pulling a Clinton and saying that they have
rdtsc without actually having one, then obviously this won't
work.... (but then, they don't deserve to be supported, so...)

- Ted

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