From: Paolo Bonzini <pbonzini@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: libvir-list@redhat.com, qemu list <qemu-devel@nongnu.org>,
Laine Stump <laine@redhat.com>,
marcel.a@redhat.com
Subject: Re: [Qemu-devel] Attaching PCI devices to the PCIe root complex
Date: Wed, 02 Oct 2013 10:53:07 +0200 [thread overview]
Message-ID: <524BDEF3.9090102@redhat.com> (raw)
In-Reply-To: <20130925085928.GA6175@redhat.com>
Il 25/09/2013 10:59, Michael S. Tsirkin ha scritto:
>> > I couldn't find on PCIe spec any mention that "Root Complex Integrated EndPoint"
>> > must be PCIe. But, from spec 1.3.2.3:
>> > - A Root Complex Integrated Endpoint must not require I/O resources claimed through BAR(s).
>> > - A Root Complex Integrated Endpoint must not generate I/O Requests.
>> > - A Root Complex Integrated Endpoint is required to support MSI or MSI-X or both if an
>> > interrupt resource is requested.
> Heh PCI-SIG keeps fighting against legacy interrupts and IO.
> But lots of hardware happily ignores these rules.
> And the reason is simple: software does not enforce them.
I think it's "must not require", not "must not have". So it's the usual
rule that applies to PCIe device, i.e. that they should work even if the
OS doesn't enable the I/O BARs.
Then I have no idea what the I/O BAR in i915 is for, and whether the
device can be used without that BAR.
Paolo
next prev parent reply other threads:[~2013-10-02 8:53 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-24 10:01 [Qemu-devel] Attaching PCI devices to the PCIe root complex Laine Stump
2013-09-25 7:01 ` Michael S. Tsirkin
2013-09-25 8:48 ` Marcel Apfelbaum
2013-09-25 8:59 ` Michael S. Tsirkin
2013-10-02 8:53 ` Paolo Bonzini [this message]
2013-10-02 9:28 ` Michael S. Tsirkin
2013-09-25 9:39 ` Laine Stump
2013-09-25 10:00 ` Michael S. Tsirkin
2013-09-25 10:14 ` Laine Stump
2013-09-25 10:56 ` Michael S. Tsirkin
2013-09-25 10:58 ` Michael S. Tsirkin
2013-09-27 17:06 ` Markus Armbruster
2013-09-28 18:12 ` Michael S. Tsirkin
2013-09-30 9:55 ` Markus Armbruster
2013-09-30 10:44 ` Laine Stump
2013-09-30 10:48 ` Michael S. Tsirkin
2013-09-30 16:01 ` Gerd Hoffmann
2013-09-30 16:06 ` Michael S. Tsirkin
2013-10-01 21:14 ` Michael S. Tsirkin
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