On Thu, Dec 16, 2004 at 10:33:54PM +0000, Charles M. Hannum wrote:
> On Thursday 16 December 2004 22:14, Manuel Bouyer wrote:
> > Hi,
> > while trying to get current/xen working again I found something that
> > I don't understannd in the x86 spllower() function:
> >
> >         struct cpu_info *ci = curcpu();
> >         u_int32_t imask;
> >         u_long psl;
> >
> >         __insn_barrier();
> >
> >         imask = IUNMASK(ci, nlevel);
> >         psl = read_psl();
> >         disable_intr();
> >         if (ci->ci_ipending & imask) {
> >                 Xspllower(nlevel);
> >                 /* Xspllower does enable_intr() */
> >         } else {
> >                 ci->ci_ilevel = nlevel;
> >                 write_psl(psl);
> >         }
> >
> > What will do enable_intr() when Xspllower() is not called ?
> 
> The interrupt flag is in the "PSL", and therefore will get restored to its 
> initial value by the write_psl().

OK, thanks. Well, this won't work for xen, where disabling/enabling interrupts
is done by writing a memory shared with the hyperviror.
Does read_psl()/write_psl() do something else than just cli/sti here ?
Could this be changed to cli()/sti() (which are macro doing the right
thing on port-xen) ?

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