Re: [Qemu-devel] [PATCH v2 0/9] target-arm: EL3 trap support

[Greg Bellows]

On Thu, Apr 23, 2015 at 5:10 AM, Peter Maydell <address@hidden> wrote:

On 23 April 2015 at 04:37, Edgar E. Iglesias <address@hidden> wrote:
> I had a comment on the trapping of WFX, I recall not checking for
> has_work was causing a lot of exception round-trips when running
> XEN. To the point were things almost stopped working.

For traps on WFE, or traps on WFI? If the former, we should
probably implement that as "never trap" since we don't actually
go into a 'low power state' for WFE (execution will always
continue even if there's no pending WFE event).

-- PMM

​I did notice that issuing a wfi without trapping causes QEMU to hang.  I had to make sure to not test the non-trapping case in EL1.  I didn't investigate too deeply, but I figured that there was nothing to wake it up.

The WFx stuff was a good test case for the trap to ELn, but if it is troublesome I can pull the patch until we arrive at a reasonable solution.  The FP stuff now also tests this.