Re: [Qemu-devel] when does a target frontend need to use gen_io_start()/gen_io_end() ?

[Pavel Dovgaluk]

> From: Paolo Bonzini [mailto:address@hidden On Behalf Of Paolo Bonzini
> On 12/05/2015 17:32, Peter Maydell wrote:
> > In order for -icount to work, it's important for the target
> > translate.c code to correctly bracket any generated code which
> > can "do I/O" with gen_io_start()/gen_io_end() calls. But
> > does anybody know exactly what the criteria are here for this?
> > It would be nice if we could document this in a comment in
> > gen_icount.h -- I'm happy to write one up if somebody will just
> > tell me what the right answer is :-)
> 
> It's any instruction that can cause an icount read, typically through
> QEMU_CLOCK_VIRTUAL or cpu_get_ticks().

Doesn't this mean that ARM has incorrect implementation of icount?
MMIO is common for this platform, but none of memory accesses are
surrounded with gen_io_start()/gen_io_end().

Pavel Dovgalyuk