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From: Cornelia Huck <cornelia.huck@de.ibm.com>
To: Marcel Apfelbaum <marcel@redhat.com>
Cc: qemu-devel@nongnu.org, mst@redhat.com
Subject: Re: [Qemu-devel] [PATCH V2] hw/virtio-pci: fix virtio behaviour on modern (PCIe) machines
Date: Wed, 20 Jul 2016 11:16:04 +0200	[thread overview]
Message-ID: <20160720111604.1573d0b7.cornelia.huck@de.ibm.com> (raw)
In-Reply-To: <1468953778-15295-1-git-send-email-marcel@redhat.com>

On Tue, 19 Jul 2016 21:42:58 +0300
Marcel Apfelbaum <marcel@redhat.com> wrote:

> Modern machines are expected to be used by newer setups with
> modern guests aiming the use of the latest features.
> 
> Enable modern and disable legacy for virtio devices
> plugged into PCIe ports (Root ports or Downstream ports).
> Using the Virtio 1 mode will remove the limitation
> of the number of devices that can be attached to a machine
> by removing the need for the IO BAR.

Stupid question: Does this limitation show up for legacy and
transitional, but not for modern?

Would it make sense then to default to modern for PCIe and transitional
for non-PCIe?

(The term "virtio-1" mode always confuses me a bit; this may be because
ccw unlike pci does not have modern-only devices - and even if we had,
basically the only difference would be that we'd disallow devices
without the VERSION_1 feature.)

  parent reply	other threads:[~2016-07-20  9:16 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-19 18:42 [Qemu-devel] [PATCH V2] hw/virtio-pci: fix virtio behaviour on modern (PCIe) machines Marcel Apfelbaum
2016-07-19 22:56 ` Michael S. Tsirkin
2016-07-20  8:27   ` Marcel Apfelbaum
2016-07-20  8:41   ` Gerd Hoffmann
2016-07-20  9:01     ` Marcel Apfelbaum
2016-07-20  9:43       ` Gerd Hoffmann
2016-07-20  9:16 ` Cornelia Huck [this message]
2016-07-20  9:37   ` Marcel Apfelbaum
2016-07-20 11:23     ` Cornelia Huck

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