From 1dc3e3bcbfe335843ec938bfdddb34d10f4dd278 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Tue, 26 Aug 2008 00:19:27 -0500 Subject: lguest: update commentry Signed-off-by: Rusty Russell --- drivers/lguest/lguest_device.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'drivers') diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c index 37344aaee22..a661bbdae3d 100644 --- a/drivers/lguest/lguest_device.c +++ b/drivers/lguest/lguest_device.c @@ -98,6 +98,10 @@ static u32 lg_get_features(struct virtio_device *vdev) return features; } +/* The virtio core takes the features the Host offers, and copies the + * ones supported by the driver into the vdev->features array. Once + * that's all sorted out, this routine is called so we can tell the + * Host which features we understand and accept. */ static void lg_finalize_features(struct virtio_device *vdev) { unsigned int i, bits; @@ -108,6 +112,10 @@ static void lg_finalize_features(struct virtio_device *vdev) /* Give virtio_ring a chance to accept features. */ vring_transport_features(vdev); + /* The vdev->feature array is a Linux bitmask: this isn't the + * same as a the simple array of bits used by lguest devices + * for features. So we do this slow, manual conversion which is + * completely general. */ memset(out_features, 0, desc->feature_len); bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8; for (i = 0; i < bits; i++) { -- cgit v1.2.3