Re: [Qemu-devel] [PATCH 23/26] target/xtensa: Convert to CPUClass::tlb_fill

[Max Filippov]

On Tue, Apr 30, 2019 at 10:44 AM Richard Henderson
<address@hidden> wrote:
> On 4/30/19 10:32 AM, Max Filippov wrote:
> > On Tue, Apr 30, 2019 at 3:11 AM Peter Maydell <address@hidden> wrote:
> >> ...but now we'll set it to whatever exception_cause_vaddr does,
> >> which is something more complicated based on the state of
> >> env->sregs[PS].
> >>
> >> We'll also end up setting env->sregs[PS] bits and env->pc, which
> >> the old code did not. (In particular since we set the PS_EXCM bit,
> >> the second time we take an exception won't we then end up
> >> setting exception_index to EXC_DOUBLE, not EXC_USER ?)
> >
> > I guess it doesn't matter, because linux-user userspace never handles
> > exceptions. PS, PC and similar must be fixed up by the linux-user
> > exception handler. But I haven't tested it.
>
> It does handle exceptions, in linux-user/xtensa/cpu_loop.c.
> And Peter's right that I should have kept EXC_USER.

PC must also either be preserved or restored from the EPC1
in the cpu_loop for the SYSCALL_CAUSE.

> > Richard, is there a branch with this series available somewhere?
> https://github.com/rth7680/qemu/tree/tcg-tlb-fill

Thanks, I'll try it.

-- 
Thanks.
-- Max