Re: [Qemu-ppc] [Qemu-devel] [PATCH v5 27/36] sysbus: add a sysbus_mmio_unmap() helper

[Peter Maydell]

On Thu, 29 Nov 2018 at 04:55, David Gibson <address@hidden> wrote:
>
> On Fri, Nov 16, 2018 at 11:57:20AM +0100, Cédric Le Goater wrote:
> > This will be used to remove the MMIO regions of the POWER9 XIVE
> > interrupt controller when the sPAPR machine is reseted.
> >
> > Signed-off-by: Cédric Le Goater <address@hidden>
>
> Reviewed-by: David Gibson <address@hidden>
>
> Since the code looks sane.
>
> Hoever, I think using memory_region_set_enabled() would be a better
> idea for our purposes than actually adding/deleting the subregion.

The other approach I've used in the past is to use
sysbus_mmio_get_region() and then just map and unmap
that directly, rather than using the sysbus_mmio_map()
convenience function. (Often the kind of device that's
doing complicated things like this will be working in
a setup where it doesn't necessarily want to be mapping
directly into system memory rather than an SoC or similar
container MemoryRegion anyway.)

thanks
-- PMM