Re: [PATCH] linux-2.5.43_vsyscall_A0

Andi Kleen
2002-10-20T02:50:43Z

On Sun, Oct 20, 2002 at 03:50:37AM +0200, Rik van Riel wrote:
> On Fri, 18 Oct 2002, Jeff Dike wrote:
>
> > My preferred solution would be for libc to ask the kernel where the
> > vsyscall area is. That's reasonably clean and virtualizable. Andrea
> > doesn't like it because it adds a few instructions to the vsyscall
> > address calculation.
>
> Sounds like the best solution indeed, especially when keeping
> in mind the strange people who want to run with a different
> user:kernel split or statically linked binaries at fun addresses
> so they've got more space for their fortran arrays ;)

x86-64 addresses that (not that it would need it) by putting vsyscalls at
the top of the virtual mapping after the direct mapped area. This part
never moves even with changed __PAGE_OFFSET. The same technique should work
on i386 too.

-Andi