On Sat, 9 Nov 2002, Zwane Mwaikambo wrote:
> This is all very confusing, notsc isnn't supposed to work with cpus with
> TSCs?
No.
You have two different cases:
- a kernel compiled for TSC-only. This one simply will not _work_ without
a TSC, since it is statically compiled for the TSC case. Here, "notsc"
simply cannot do anything, so it just prints a message saying that it
doesn't work.
- a "generic" kernel, which can do the TSC decision dynamically, will use
the TSC flag in the CPU features field to decide whether to use the TSC
or not. Here, "notsc" will clear the flag unconditionally, so even if
your CPU claims to have a TSC, it won't get used.
NOTE! We used to do a lot more statically, and on the whole the hard-coded
CONFIG_X86_TSC usage has pretty much disappeared in modern kernels. It's
used mainly by the "get_cycles()" macro, which is not all that commonly
used any more (it used to be used by the scheduler, I think that's gone
too these days).
Linus
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This archive was generated by hypermail 2b29 : Fri Nov 15 2002 - 22:00:18 EST