Re: [Qemu-devel] [PATCH v1 8/8] usb/ehci: Put RAM in undefined MMIO regions

[Avi Kivity <avi@redhat.com>]

On 10/25/2012 03:03 PM, Peter Crosthwaite wrote:
> On Thu, Oct 25, 2012 at 10:19 PM, Gerd Hoffmann <kraxel@redhat.com> wrote:
>> On 10/25/12 11:47, Peter Crosthwaite wrote:
>>> Just put RAM regions in the unimplemented spaces in the MMIO region. These
>>> regions have undefined behaviour, but this at least stops QEMU from segfaulting
>>> when the guest bangs on these registers (and sucessfully fakes reading and
>>> writing the registers with no side effects).
>>
>> Should not be needed, memory api should deal with that properly.
> 
> CC Avi,
> 
> Whats going on here is there is a container of size 0x1000 created
> with memory_region_init() and a handful of small subregions are
> populated. the container is then mapped to a 0x1000 size region of the
> system memory. What is supposed to happen when the guest access a
> region in the container for which no subregion has been added? 

It falls back to the parent container.  If there isn't one, something
system-specific happens.  You can override that by initializing your
container with memory_region_init_io(); the callbacks will then receive
any accesses which are not caught by any subregion.



-- 
error compiling committee.c: too many arguments to function