[ipxe-devel] [PATCH 0/4] Implement virtio 1.0 support

[Michael S. Tsirkin]

On Wed, Mar 09, 2016 at 09:39:44PM +0100, Ladi Prosek wrote:
> On Wed, Mar 9, 2016 at 9:25 PM, Michael S. Tsirkin <mst at redhat.com> wrote:
> > Thanks a lot for looking into this!
> > I'll review early next week.
> >
> > On Wed, Mar 09, 2016 at 07:19:59PM +0100, Ladi Prosek wrote:
> >> The goal here is to support booting from modern only (non-transitional)
> >> virtio-net devices.
> >
> > Side-note: it is preferable to use transitional
> > devices through the modern interface, as well.
> 
> That's actually the case in this series, apologies for the inaccurate
> wording. If the VIRTIO_PCI_CAP_COMMON_CFG capability is found, the
> driver uses the modern interface.
> 
> > Some advantages include:
> >         - ability to work without enabling IO space (or even memory space)
> >         - ability to reduce ring size, and generally lower memory consumption
> 
> Gotcha. I made no changes to the ring layout in this series in order
> to keep it simple. My understanding is that minimizing the code size
> here could be more important than optimizing run-time performance (the
> driver ignores pretty much all virtio-net feature flags for example)
> but I'm open to suggestions.

It's not about performance - I believe in the past number of
bootable NICs was limited because we run out of
memory for the rings+packets.

But these optimizations can come later.

> >> The code strives to comply with the virtio 1.0 spec
> >> and is heavily inspired by the Linux kernel implementation.
> >>
> >> One notable divergence from Linux is the explicit differentiation
> >> between port I/O and memory I/O due to the lack of __iomem in iPXE. See
> >> struct virtio_pci_region for details.
> >>
> >>  src/drivers/bus/pciextra.c     |  54 ++++++---
> >>  src/drivers/bus/virtio-pci.c   | 213 ++++++++++++++++++++++++++++++++-
> >>  src/drivers/bus/virtio-ring.c  |  12 +-
> >>  src/drivers/net/virtio-net.c   | 259 +++++++++++++++++++++++++++++++++++++++--
> >>  src/drivers/net/virtio-net.h   |  18 +++
> >>  src/include/ipxe/errfile.h     |   1 +
> >>  src/include/ipxe/pci.h         |   2 +
> >>  src/include/ipxe/virtio-pci.h  | 231 ++++++++++++++++++++++++++++++++++++
> >>  src/include/ipxe/virtio-ring.h |   9 ++
> >>  9 files changed, 769 insertions(+), 30 deletions(-)
> >>
> >> [PATCH 1/4] [pci] Add pci_find_next_capability
> >> [PATCH 2/4] [virtio] Add virtio 1.0 constants and data structures
> >> [PATCH 3/4] [virtio] Add virtio 1.0 PCI support
> >> [PATCH 4/4] [virtio] Add virtio-net 1.0 support