From: "Michael S. Tsirkin" <mst@redhat.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: virtualization@lists.linux-foundation.org
Subject: Re: [PATCH 12/22] virtio_pci: allow duplicate capabilities.
Date: Thu, 21 Mar 2013 17:19:37 +0200 [thread overview]
Message-ID: <20130321151937.GB1454@redhat.com> (raw)
In-Reply-To: <514B1D25.9090206@zytor.com>
On Thu, Mar 21, 2013 at 07:45:57AM -0700, H. Peter Anvin wrote:
> On 03/21/2013 07:43 AM, Michael S. Tsirkin wrote:
> >>
> >> The reason to support this is that a guest written to only handle one or
> >> the other doesn't prevent the hypervisor from offering the other to
> >> guests. We probably want to specify that if the guest doesn't care, it
> >> should use the first one offered by the host.
> >>
> >
> > What are the configurations where having many ways is helpful?
> > Any examples?
> >
>
> In BIOS (e.g. SeaBIOS), using MMIO is very difficult, so your boot ROM
> probably wants to use I/O space even if MMIO is available.
Is this a real concern? Modern cards seem to supply PXE ROMs even
though they have no IO BARs.
> If you are preferring I/O space because it is faster (vmexit), then you
> still want to allow MMIO if the resource is not available.
>
> -hpa
Problem is, BIOS and OS normally assume failure to allocate
any resources means card won't function and disable it.
So it does not seem to be worth it to have such a
device specific failover ability.
> --
> H. Peter Anvin, Intel Open Source Technology Center
> I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2013-03-21 15:19 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-21 8:29 [PATCH 00/22] New virtio PCI layout Rusty Russell
2013-03-21 8:29 ` [PATCH 01/22] virtio_config: introduce size-based accessors Rusty Russell
2013-03-21 8:29 ` [PATCH 02/22] virtio_config: use " Rusty Russell
2013-03-21 8:29 ` [PATCH 03/22] virtio_config: make transports implement accessors Rusty Russell
2013-03-21 9:09 ` Cornelia Huck
2013-03-22 0:31 ` Rusty Russell
2013-03-22 9:13 ` Cornelia Huck
2013-03-22 14:43 ` Sjur Brændeland
2013-03-24 4:24 ` Rusty Russell
2013-04-03 15:58 ` Sjur Brændeland
2013-04-02 17:16 ` Pawel Moll
2013-03-21 8:29 ` [PATCH 04/22] virtio: use u32, not bitmap for struct virtio_device's features Rusty Russell
2013-03-21 10:00 ` Cornelia Huck
2013-03-22 0:48 ` Rusty Russell
2013-03-21 8:29 ` [PATCH 05/22] virtio: add support for 64 bit features Rusty Russell
2013-03-21 10:06 ` Cornelia Huck
2013-03-22 0:50 ` Rusty Russell
2013-03-22 9:15 ` Cornelia Huck
2013-03-22 14:50 ` Sjur Brændeland
2013-03-22 20:12 ` Ohad Ben-Cohen
2013-03-25 8:30 ` Rusty Russell
2013-04-02 17:09 ` Pawel Moll
2013-03-21 8:29 ` [PATCH 06/22] virtio: move vring structure into struct virtqueue Rusty Russell
2013-03-21 8:29 ` [PATCH 07/22] pci: add pci_iomap_range Rusty Russell
2013-03-21 8:29 ` [PATCH 08/22] virtio-pci: define layout for virtio vendor-specific capabilities Rusty Russell
2013-03-21 8:29 ` [PATCH 09/22] virtio_pci: move old defines to legacy, introduce new structure Rusty Russell
2013-03-21 8:29 ` [PATCH 10/22] virtio_pci: use _LEGACY_ defines in virtio_pci_legacy.c Rusty Russell
2013-03-21 8:29 ` [PATCH 11/22] virtio_pci: don't use the legacy driver if we find the new PCI capabilities Rusty Russell
2013-03-21 8:29 ` [PATCH 12/22] virtio_pci: allow duplicate capabilities Rusty Russell
2013-03-21 10:28 ` Michael S. Tsirkin
2013-03-21 14:26 ` H. Peter Anvin
2013-03-21 14:43 ` Michael S. Tsirkin
2013-03-21 14:45 ` H. Peter Anvin
2013-03-21 15:19 ` Michael S. Tsirkin [this message]
2013-03-21 15:26 ` H. Peter Anvin
2013-03-21 15:58 ` Michael S. Tsirkin
2013-03-21 16:04 ` H. Peter Anvin
2013-03-21 16:11 ` Michael S. Tsirkin
2013-03-21 16:15 ` H. Peter Anvin
2013-03-21 16:26 ` Michael S. Tsirkin
2013-03-21 16:32 ` H. Peter Anvin
2013-03-21 17:07 ` Michael S. Tsirkin
2013-03-21 17:09 ` H. Peter Anvin
2013-03-21 17:13 ` Michael S. Tsirkin
2013-03-21 17:49 ` Michael S. Tsirkin
2013-03-21 17:54 ` H. Peter Anvin
2013-03-21 18:01 ` Michael S. Tsirkin
2013-03-22 0:57 ` Rusty Russell
2013-03-22 3:17 ` H. Peter Anvin
2013-03-24 13:14 ` Michael S. Tsirkin
2013-03-24 23:23 ` H. Peter Anvin
2013-03-25 6:53 ` Michael S. Tsirkin
2013-03-25 6:54 ` H. Peter Anvin
2013-03-25 10:03 ` Rusty Russell
2013-03-21 8:29 ` [PATCH 13/22] virtio_pci: new, capability-aware driver Rusty Russell
2013-03-21 10:24 ` Michael S. Tsirkin
2013-03-22 1:02 ` Rusty Russell
2013-03-24 13:08 ` Michael S. Tsirkin
2013-03-21 8:29 ` [PATCH 14/22] virtio_pci: layout changes as per hpa's suggestions Rusty Russell
2013-03-21 8:29 ` [PATCH 15/22] virtio_pci: use little endian for config space Rusty Russell
2013-03-21 8:29 ` [PATCH 16/22] virtio_pci: use separate notification offsets for each vq Rusty Russell
2013-03-21 10:13 ` Michael S. Tsirkin
2013-03-21 10:35 ` Michael S. Tsirkin
2013-03-22 2:52 ` Rusty Russell
2013-03-24 14:38 ` Michael S. Tsirkin
2013-03-24 20:19 ` Michael S. Tsirkin
2013-03-24 23:27 ` H. Peter Anvin
2013-03-25 7:05 ` Michael S. Tsirkin
2013-03-25 10:00 ` Rusty Russell
2013-03-26 19:39 ` Michael S. Tsirkin
2013-03-27 0:07 ` Rusty Russell
2013-03-27 0:22 ` H. Peter Anvin
2013-03-27 2:31 ` H. Peter Anvin
2013-03-27 11:26 ` Michael S. Tsirkin
2013-03-27 14:21 ` H. Peter Anvin
2013-03-27 11:25 ` Michael S. Tsirkin
2013-03-28 4:50 ` H. Peter Anvin
2013-03-30 3:19 ` Rusty Russell
2013-04-02 22:51 ` H. Peter Anvin
2013-04-03 6:10 ` Rusty Russell
2013-04-03 11:22 ` Michael S. Tsirkin
2013-04-03 14:10 ` H. Peter Anvin
2013-04-03 14:35 ` Michael S. Tsirkin
2013-04-03 14:35 ` H. Peter Anvin
2013-04-03 17:02 ` Michael S. Tsirkin
2013-04-04 5:48 ` Rusty Russell
2013-04-04 8:25 ` Michael S. Tsirkin
2013-04-05 1:25 ` Rusty Russell
2013-03-21 8:29 ` [PATCH 17/22] virtio_pci_legacy: cleanup struct virtio_pci_vq_info Rusty Russell
2013-03-21 8:29 ` [PATCH 18/22] virtio_pci: share structure between legacy and modern Rusty Russell
2013-03-21 8:29 ` [PATCH 19/22] virtio_pci: share interrupt/notify handlers " Rusty Russell
2013-03-21 8:29 ` [PATCH 20/22] virtio_pci: share virtqueue setup/teardown between modern and legacy driver Rusty Russell
2013-03-21 8:29 ` [PATCH 21/22] virtio_pci: simplify common helpers Rusty Russell
2013-03-21 8:29 ` [PATCH 22/22] virtio_pci: fix finalize_features in modern driver Rusty Russell
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