Re: [Qemu-devel] ARM softmmu breakpoint misbehavior

[Peter Maydell]

On 2 September 2015 at 20:08, Sergey Fedorov <address@hidden> wrote:
> With the following patch the test is okay, but I am not sure that this
> is a clean solution. Anyway, we can't do such a simple hack for
> breakpoints. Seems that this is a systematic problem which can affect
> all architectures.

I think it won't affect architectures that don't set BP_STOP_BEFORE_ACCESS,
because for those we will execute the load before trying to see if there
is a watchpoint to take, and if there's no CPU watchpoint we'll be able
to continue normally. So ARM, LM32, S390x and Xtensa might be affected.
And of course any architecture which only sets up wps/bps which will
definitely be hit architecturally when QEMU thinks they've been hit
will be fine.

Maybe rather than trying to be clever with the existing wp APIs
we should have support for targets to register "did this really hit?"
callbacks that get called before the core code tries to really
generate the exception.

I don't think I can really look in detail at this problem til next
week at the earliest, though.

thanks
-- PMM