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Re: FOR REVIEW: New x86-64 vsyscall vgetcpu()
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Andi Kleen <ak at suse dot de>
- Cc: Zoltan Menyhart <Zoltan dot Menyhart at bull dot net>, Jes Sorensen <jes at sgi dot com>, Tony Luck <tony dot luck at intel dot com>, discuss at x86-64 dot org, linux-kernel at vger dot kernel dot org, libc-alpha at sourceware dot org, vojtech at suse dot cz, linux-ia64 at vger dot kernel dot org
- Date: Fri, 16 Jun 2006 18:33:15 +0200
- Subject: Re: FOR REVIEW: New x86-64 vsyscall vgetcpu()
- References: <200606140942.31150.ak@suse.de> <200606161737.06132.ak@suse.de> <20060616155804.GN3823@sunsite.mff.cuni.cz> <200606161824.52620.ak@suse.de>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Fri, Jun 16, 2006 at 06:24:52PM +0200, Andi Kleen wrote:
> I wonder why it happened on x86-64 though - i thought there were no negative
> offsets on x86-64 TLS.
It uses negative offsets for __thread vars and positive are reserved for
implementation (i.e. glibc). But as %fs in 64-bit programs is just
msr 0xc0000100 base addition, with no segment limit, neither Xen nor VMWare
can play limit tricks with it.
Jakub