Messages in this thread |  | | From | "H. Peter Anvin" <> | Subject | Re: Microsecond accuracy | Date | 7 Dec 2000 07:33:23 -0800 |
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Followup to: <Pine.LNX.4.21.0012071411170.970-100000@penguin.homenet> By author: Tigran Aivazian <tigran@veritas.com> In newsgroup: linux.dev.kernel > > while we are on this subject, please let me emphasize that you should > _not_ be using cpuid instruction to detect the presence of TSC but should > parse the /proc/cpuinfo file. There are many valid reasons why Linux's > idea of TSC presence may not be the same as hardware's (cpuid > instruction) idea. >
Unfortunately the most important instance of the in-kernel flag -- the global one in the somewhat misnamed boot_cpu_data.x86_features -- isn't actually readable in the /proc/cpuinfo file. It is perfectly possible (e.g. the "notsc" option) for ALL the CPUs to report this capability, but the global capability to still be off.
I would like to have exported the global capabilities into /proc/cpuinfo, but I'm worried about breaking software (the "flags" versus "features" issue was bad enough -- unfortunately, in cases like this, there probably is no "good" solution.)
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