[Buildroot] [PATCH] package/glibc: enable lock elision on x86_64 hosts

[Baruch Siach]

Hi Thomas,

On Sun, Jul 19, 2015 at 11:23:14AM +0200, Thomas Petazzoni wrote:
> On Wed, 18 Mar 2015 15:01:09 -0700, Steven Noonan wrote:
> > Signed-off-by: Steven Noonan <steven at uplinklabs.net>
> > ---
> >  package/glibc/glibc.mk | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/package/glibc/glibc.mk b/package/glibc/glibc.mk
> > index 0a37bb3..651711a 100644
> > --- a/package/glibc/glibc.mk
> > +++ b/package/glibc/glibc.mk
> > @@ -90,6 +90,7 @@ define GLIBC_CONFIGURE_CMDS
> >  		--prefix=/usr \
> >  		--enable-shared \
> >  		$(if $(BR2_SOFT_FLOAT),--without-fp,--with-fp) \
> > +		$(if $(BR2_x86_64),--enable-lock-elision,) \
> 
> What happens on x86-64 processors that don't have the HW support needed
> for lock elision ? Does glibc gracefully falls back at runtime to
> "normal" locks ?

According to the code at sysdeps/unix/sysv/linux/x86/elision-conf.c, 
__elision_available is initialized from HAS_RTM which is evaluated at run-time 
(sysdeps/x86_64/multiarch/init-arch.h).

baruch

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