Re: [PATCH] x86: don't compile vsmp_64 for 32bit

From: Jeremy Fitzhardinge
Date: Wed Mar 25 2009 - 19:59:21 EST


Ravikiran G Thirumalai wrote:
The point in this thread was, is_vsmp_box() needs to be meaningful even when
CONFIG_X86_VSMP is not on. This is needed because is_vsmp_box() is used to
determine if the platform has reliable tscs.

Well, as I said, that code is inoperative at present. But aside from that, how well will a non-VSMP kernel work on your hardware, with a normal cacheline, etc. Is the tsc stability really all that important, given that the kernel should notice if the tsc is busted pretty quickly anyway.

unsynchronized_tsc() just returns a guess anyway, and if you don't have X86_FEATURE_CONSTANT_TSC set, then it will return unstable for your hardware anyway, even without the is_vsmp_box() test.

Failing that, you could add yourself to bad_tsc_dmi_table[] and have that mark the tsc as unstable (you have DMI, right?).

J


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