From: Rusty Russell <rusty@rustcorp.com.au>
Date: Mon, 22 Oct 2007 01:03:40 +0000 (+1000)
Subject: Virtio helper routines for a descriptor ringbuffer implementation
X-Git-Tag: v2.6.24-rc1~28^2~10
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0a8a69dd77ddbd4513b21363021ecde7e1025502;p=pandora-kernel.git

Virtio helper routines for a descriptor ringbuffer implementation

These helper routines supply most of the virtqueue_ops for hypervisors
which want to use a ring for virtio.  Unlike the previous lguest
implementation:

1) The rings are variable sized (2^n-1 elements).
2) They have an unfortunate limit of 65535 bytes per sg element.
3) The page numbers are always 64 bit (PAE anyone?)
4) They no longer place used[] on a separate page, just a separate
   cacheline.
5) We do a modulo on a variable.  We could be tricky if we cared.
6) Interrupts and notifies are suppressed using flags within the rings.

Users need only get the ring pages and provide a notify hook (KVM
wants the guest to allocate the rings, lguest does it sanely).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dor Laor <dor.laor@qumranet.com>
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