Re: Base GDB tracing 32bit applications on amd64 kernel (with 64bit debugger) part 1)

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Sat, Jul 20, 2019 at 09:40:38AM +0200, Maxime Villard wrote:
> Le 17/07/2019 à 11:08, Manuel Bouyer a écrit :
> > On Wed, Jul 17, 2019 at 11:00:04AM +0200, Martin Husemann wrote:
> > > >   - Xen is causing some problems here (as usual...). See process_write_regs(),
> > > >     we are resetting the ss/cs registers to the default values. Yet in
> > > >     cpu_setmcontext32 we suddenly don't care about resetting ss/cs to the
> > > >     default values. It's not clear to me which side is incorrect.
> > > 
> > > Cc'ing Manuel - can you check this, please?
> > 
> > I'm probably missing something. there's no Xen-specific code in
> > process_write_regs()
> 
> ? There is a #ifdef XENPV in this very function.
> 
> The point was: there is an asymmetry between process_write_regs() and
> cpu_setmcontext32(), because the former resets ss/cs, and the latter
> does not. One side has to be incorrect, but it's not clear which.

But process_write_regs() is for 64bit processes, while cpu_setmcontext32()
is for 32bits, isn't it ?
netbsd32_process_write_regs() doens't reset ss/cs registers; and because
we are in 32bit mode I guess this is correct.
And there's no #ifdef XEN* in netbsd32_machdep.c

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
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