Re: [Qemu-devel] [PATCH v2 11/11] usb/ehci: Put RAM in undefined MMIO regions

[Gerd Hoffmann]

On 10/26/12 07:47, 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).

Make that an io region, have the read() handler return 0xff, write
handler do nothing except maybe logging/tracing the access for debugging
purposes.  That is more correct for unassigned mmio space than backing
by memory.  Adding memory also breaks migration btw.

I somehow still think this should be handled one layer up (i.e. the
parent region) which could do the approximate arch-specific action.

Any chance the access you are seeing is at offset 0x68?

cheers,
  Gerd