Messages in this thread | | | Date | Thu, 08 May 2008 09:48:11 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] x86: introduce a new Linux defined feature flag for PAT support |
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Thomas Gleixner wrote: >> The 'if this happens on the secondary CPU' sounds a bit like this is >> directly checking the secondary CPU flag but cpu_has_pat translates into >> boot_cpu_has(X86_FEATURE_PAT), refers always to the boot cpu.
No, it doesn't. Although it is badly named, it refers to the common capability set of all online CPUs.
> Right and thats fine because of: > > /* > * On SMP, boot_cpu_data holds the common feature set between > * all CPUs; so make sure that we indicate which features are > * common between the CPUs. The first time this routine gets > * executed, c == &boot_cpu_data. > */ > if (c != &boot_cpu_data) { > /* AND the already accumulated flags with these */ > for (i = 0 ; i < NCAPINTS ; i++) > boot_cpu_data.x86_capability[i] &= c->x86_capability[i]; > }
... because of this code. :)
-hpa
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