[RFC PATCH] getcpu_cache system call: caching current CPU number (x86)

[josh@joshtriplett.org]

On Mon, Jul 20, 2015 at 10:41:09AM -0700, Andy Lutomirski wrote:
> On Mon, Jul 20, 2015 at 8:32 AM, Florian Weimer <fweimer@redhat.com> wrote:
> > On 07/20/2015 05:31 PM, Andy Lutomirski wrote:
> >> On Jul 20, 2015 1:35 AM, "Florian Weimer" <fweimer@redhat.com> wrote:
> >>>
> >>> On 07/18/2015 01:33 AM, Andy Lutomirski wrote:
> >>>
> >>>> I think the API should be "set gsbase to x + y*(cpu number)".  On
> >>>> x86_64, userspace just allocates a big swath of virtual space and
> >>>> populates it as needed.
> >>>
> >>> This will break WINE and similar applications which use %gs today.
> >>
> >> Presumably WINE could just opt not to use this facility, just like
> >> WINE will have to opt out of whatever the enterprise people who want
> >> WRGSBASE were thinking of doing with it.
> >
> > How is this possible if it's process-global attribute and glibc or some
> > library in the process starts using it?
> >
> 
> glibc will have to expose a way to turn it off, I guess. (ELF flag?)

Or a way to turn it on.

- Josh Triplett