lkml.org 
[lkml]   [2008]   [May]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] x86: introduce a new Linux defined feature flag for PAT support
    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


    \
     
     \ /
      Last update: 2008-05-08 18:51    [W:2.204 / U:0.316 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site