From: Paolo Bonzini <pbonzini@redhat.com>
To: Paul Durrant <Paul.Durrant@citrix.com>,
Martin Cerveny <M.Cerveny@computer.org>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
George Dunlap <George.Dunlap@citrix.com>
Subject: Re: Overlaped PIO with multiple ioreq_server (Xen4.6.1)
Date: Mon, 9 May 2016 14:55:45 +0200 [thread overview]
Message-ID: <573088D1.3080400@redhat.com> (raw)
In-Reply-To: <a4c52d618821405c8bdab370828e3e0e@AMSPEX02CL03.citrite.net>
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), 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.
Paolo
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next prev parent reply other threads:[~2016-05-09 12:55 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-27 19:38 Overlaped PIO with multiple ioreq_server (Xen4.6.1) Martin Cerveny
2016-04-28 8:50 ` George Dunlap
2016-04-28 9:46 ` Paul Durrant
2016-04-28 11:16 ` Martin Cerveny
2016-04-28 11:25 ` Paul Durrant
2016-05-09 12:55 ` Paolo Bonzini [this message]
2016-05-09 12:59 ` Paul Durrant
2016-05-09 16:02 ` Paul Durrant
2016-05-09 16:14 ` Paul Durrant
2016-05-09 16:18 ` Paolo Bonzini
2016-05-09 16:19 ` Paul Durrant
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