Re: [RFC virtio-next 0/4] Introduce CAIF Virtio and reversed Vrings

From: Rusty Russell <rusty@rustcorp•com.au>
To: "Sjur Brændeland" <sjur@brendeland•net>
Cc: "Michael S. Tsirkin" <mst@redhat•com>,
	netdev@vger•kernel.org, Linus Walleij <linus.walleij@linaro•org>,
	dmitry.tarnyagin@stericsson•com, linux-kernel@vger•kernel.org,
	virtualization@lists•linux-foundation.org, sjur@brendeland•net
Subject: Re: [RFC virtio-next 0/4] Introduce CAIF Virtio and reversed Vrings
Date: Thu, 01 Nov 2012 18:11:35 +1030	[thread overview]
Message-ID: <87wqy54vo0.fsf@rustcorp.com.au> (raw)
In-Reply-To: <1351723614-4145-1-git-send-email-sjur@brendeland.net>

Sjur Brændeland <sjur@brendeland•net> writes:
> Zero-Copy data transport on the modem is primary goal for CAIF Virtio.
> In order to achieve Zero-Copy the direction of the Virtio rings are
> flipped in the RX direction. So we have implemented the Virtio
> access-function similar to what is found in vhost.c.

So, this adds another host-side virtqueue implementation.

Can we combine them together conveniently?  You pulled out more stuff
into vring.h which is a start, but it's a bit overloaded.

Perhaps we should separate the common fields into struct vring, and use
it to build:

        struct vring_guest {
                struct vring vr;
                u16 last_used_idx;
        };

        struct vring_host {
                struct vring vr;
                u16 last_avail_idx;
        };

I haven't looked closely at vhost to see what it wants, but I would
think we could share more code.

Cheers,
Rusty.
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