lguest: update commentry

[linux-2.6-omap-h63xx.git] / drivers / lguest / lguest_device.c

diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index 37344aaee22f3ab44910a18576489466c0b8c30d..a661bbdae3d62f657fc801eceb80d9afefc3e4bf 100644 (file)
--- 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++) {