Re: [patch 2.6.15] i386: allow disabling X86_FEATURE_SEP at boot

[Chuck Ebbert <76306.1226@compuserve.com>]

In-Reply-To: <20060127143713.2efc16ed.akpm@osdl.org>

On Fri, 27 Jan 2006 at 14:37:13 -0800, Andrew Morton wrote:

> Chuck Ebbert <76306.1226@compuserve.com> wrote:
> >
> > Allow the x86 "sep" feature to be disabled at bootup.  This
> > forces use of the int80 vsyscall.
> > 
>
> Why is there a need to do this?

Mainly for testing or benchmarking the int80 vsyscall code.

> > --- 2.6.15a.orig/arch/i386/kernel/cpu/common.c
> > +++ 2.6.15a/arch/i386/kernel/cpu/common.c
> > @@ -27,6 +27,7 @@ EXPORT_PER_CPU_SYMBOL(cpu_16bit_stack);
> >  static int cachesize_override __devinitdata = -1;
> >  static int disable_x86_fxsr __devinitdata = 0;
> >  static int disable_x86_serial_nr __devinitdata = 1;
> > +static int disable_x86_sep __devinitdata = 0;
> >  
>
> hm, I guess lots of things in there should be __cpuinit/__cpuinitdata. 

I'll try to do that.

> __devinit is a superset of that, but we're being a little wasteful in the
> case of CONFIG_HOTPLUG&&!CONFIG_HOTPLUG_CPU.

-- 
Chuck

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