Re: [Qemu-arm] [Qemu-devel] [PATCH] target/arm: Allow to switch from MON->HYP on AArch32

[Peter Maydell]

On Thu, 10 Jan 2019 at 10:34, Peter Maydell <address@hidden> wrote:
>
> On Thu, 10 Jan 2019 at 06:43, Alexander Graf <address@hidden> wrote:
> >
> >
> >
> > On 10.01.19 00:08, Peter Maydell wrote:
> > > On Wed, 9 Jan 2019 at 17:14, Alexander Graf <address@hidden> wrote:
> > >>
> > >> On 01/09/2019 05:59 PM, Peter Maydell wrote:
> > >>> On Wed, 9 Jan 2019 at 16:52, Peter Maydell <address@hidden> wrote:
> > >>>> On Wed, 9 Jan 2019 at 15:26, Alexander Graf <address@hidden> wrote:
> > >>>>> In U-boot, we switch from S-SVC -> MON -> HYP when we want to enter
> > >>>>> HYP mode. This dance seems to work ok (hence it's there in the code
> > >>>>> base), but breaks with current QEMU.
> > >>> PS: it would be helpful if the commit message said how u-boot
> > >>> is trying to go from Mon to Hyp -- some ways to try to do
> > >>> this are OK, and some are not, so whether it's supposed to
> > >>> work or not depends on what u-boot is actually doing...
> > >>
> > >> I don't fully understand all of it to be honest :). But the code is here:
> > >>
> > >> http://git.denx.de/?p=u-boot.git;a=blob;f=arch/arm/cpu/armv7/nonsec_virt.S
> > >>
> > >> What I managed to understand so far is that it goes to MON using the smc
> > >> #0 call and then changes SPSR so that on return (movs pc) the mode will
> > >> be different.
> > >
> > > Thanks -- yes, that's an exception return so it's the
> > > expected way to go from Mon to Hyp.
> >
> > That was my understanding, yes. Do you still want me to change the
> > commit message to mention that or will you just do it when applying?
>
> I'll add a note when I apply it; thanks.

Now applied to target-arm.next with a rewritten commit message; thanks.

-- PMM