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    SubjectRe: [PATCH RFC] virtio-spec: flexible configuration layout
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    On Wed, 2011-11-09 at 12:18 +0200, Michael S. Tsirkin wrote:
    > On Wed, Nov 09, 2011 at 11:55:02AM +0200, Sasha Levin wrote:
    > > On Tue, 2011-11-08 at 23:40 +0200, Michael S. Tsirkin wrote:
    > > > Here's a spec change documenting what my C patch does
    > > > (almost - I tweaked the layout a bit, but the idea is the same).
    > > > Some more cleanups are needed but I thought I'd send it
    > > > for early flames/comments.
    > > >
    > > > The idea is simple: we split functionally unrelated
    > > > register groups to independent structures, and let
    > > > the device place is anywhere using a capability
    > > > in PCI configuration space.
    > >
    > > I'm also wondering it it's ok to move virtio configuration out of virtio
    > > space and into PCI space for archs that don't have PCI (such as ARM).
    >
    > A bit of confusion here: no register is moved from memory into
    > configuration space. Configuration space only gains a list of
    > pointers into memory/pio space.

    The definition of the way the virtio configuration space looks is moved
    into PCI configuration space, it was constant before.

    > > Would it mean they get stuck with legacy configuration (and no new
    > > features)? Or is there an alternative for them?
    >
    > The change only affects the layout of virtio PCI. Arches that don't
    > have PCI don't use virtio PCI, presumably?
    >
    > BTW, the spec only covers x86 ATM, this needs to be fixed.

    From what I see there is a WIP by Pawel Moll <pawel.moll@arm.com> to add
    virtio platform drivers which get virtio working on ARM for example, and
    by Peter Maydell <peter.maydell@linaro.org> to modify the spec to
    support MMIO access (besides PCI).

    Maybe worth seeing if it works for them...

    --

    Sasha.



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