> -----Original Message----- > From: Xen-devel [mailto:xen-devel-boun...@lists.xen.org] On Behalf Of > Paul Durrant > Sent: 09 May 2016 14:00 > To: Paolo Bonzini; Martin Cerveny > Cc: xen-de...@lists.xensource.com; George Dunlap > Subject: Re: [Xen-devel] Overlaped PIO with multiple ioreq_server > (Xen4.6.1) > > > -----Original Message----- > > From: Paolo Bonzini [mailto:pbonz...@redhat.com] > > Sent: 09 May 2016 13:56 > > To: Paul Durrant; Martin Cerveny > > Cc: George Dunlap; xen-de...@lists.xensource.com > > Subject: Re: [Xen-devel] Overlaped PIO with multiple ioreq_server > > (Xen4.6.1) > > > > > > > > On 28/04/2016 13:25, Paul Durrant wrote: > > >> Maybe you are lucky, qemu is registered before your own demu > > >> emulator. > > > > > > I guess I was lucky. > > > > Yeah, QEMU has been doing that since 2013 (commit 3bb28b7, "memory: > > Provide separate handling of unassigned io ports accesses", 2013-09-05). > > > > >> I used for testing your "demu" 2 years ago, now extending Citrix > > >> "vgpu", all was fine up to xen 4.5.2 (with qemu 2.0.2) but > > >> problem begin when I switched to 4.6.1 (with qemu 2.2.1), but it > > >> maybe lucky timing in registration. > > > > > > I think Xen should really be spotting range overlaps like this, but > > > the QEMU<->Xen interface will clearly need to be fixed to avoid the > > > over-claiming of I/O ports like this. > > > > If the handling of unassigned I/O ports is sane in Xen (in QEMU they > > return all ones and discard writes), > > Yes, it does exactly that. > > > it would be okay to make the > > background 0-65535 range conditional on !xen_enabled(). See > > memory_map_init() in QEMU's exec.c file. > > > > Cool. Thanks for the tip. Will have a look at that now. >
Looks like creation of the background range is required. (Well, when I simply #if 0-ed out creating it QEMU crashed on invocation). So, I guess I need to be able to spot, from the memory listener callback in Xen, when a background range is being added so it can be ignored. Same actually goes for memory as well as I/O, since Xen will handle access to unimplemented MMIO ranges in a similar fashion. Paul > Cheers, > > Paul > > > Paolo > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
