Re: [Qemu-devel] [PATCH] Revived GUEST_BASE support for usermode emulation targets [v4]

[Paul Brook <paul@codesourcery.com>]

On Friday 15 May 2009, Riku Voipio wrote:
> On Fri, May 15, 2009 at 03:25:31AM +0100, Paul Brook wrote:
> > On Tuesday 05 May 2009, Riku Voipio wrote:
> > > On Tue, May 05, 2009 at 10:02:41PM +0400, malc wrote:
> > > > Things should work the way they are in your latest patch on x86 and
> > > > should be done the way it's done in the original submission (mov +
> > > > add) for x86_64.
> > >
> > > Ok.. here we go. not on a amd64 machine right now so I will test
> > > that part tomorrow.
> >
> > I'm pretty sure it's still broken for large offsets.
>
> It is indeed broken. Since tcg_out_addi maps on x86_64 to tgen_arithi64
> which doesn't accept 64bit values. But as Martin said, the currrent use for
> this patch is just to add very minimal offsets.

I that case you should be using lea for small offsets. The proper sequence for 
large offsets is movq (allows 64-bit immedaise); add.

The offset is a user configurable option, so IMHO you should be supporting 
large offsets.

Paul