nfsd4.1: common slot allocation size calculation

[safe/jmp/linux-2.6] / include / linux / lguest_launcher.h

diff --git a/include/linux/lguest_launcher.h b/include/linux/lguest_launcher.h
index c41fd48..495203f 100644 (file)
--- a/include/linux/lguest_launcher.h
+++ b/include/linux/lguest_launcher.h
@@ -10,7 +10,15 @@
  * real devices (think of the damage it could do!) we provide virtual devices.
  * We could emulate a PCI bus with various devices on it, but that is a fairly
  * complex burden for the Host and suboptimal for the Guest, so we have our own
- * "lguest" bus and simple drivers.
+ * simple lguest bus and we use "virtio" drivers.  These drivers need a set of
+ * routines from us which will actually do the virtual I/O, but they handle all
+ * the net/block/console stuff themselves.  This means that if we want to add
+ * a new device, we simply need to write a new virtio driver and create support
+ * for it in the Launcher: this code won't need to change.
+ *
+ * Virtio devices are also used by kvm, so we can simply reuse their optimized
+ * device drivers.  And one day when everyone uses virtio, my plan will be
+ * complete.  Bwahahahah!
  *
  * Devices are described by a simplified ID, a status byte, and some "config"
  * bytes which describe this device's configuration.  This is placed by the
@@ -19,15 +27,24 @@
 struct lguest_device_desc {
        /* The device type: console, network, disk etc.  Type 0 terminates. */
        __u8 type;
-       /* The number of bytes of the config array. */
+       /* The number of virtqueues (first in config array) */
+       __u8 num_vq;
+       /*
+        * The number of bytes of feature bits.  Multiply by 2: one for host
+        * features and one for Guest acknowledgements.
+        */
+       __u8 feature_len;
+       /* The number of bytes of the config array after virtqueues. */
        __u8 config_len;
        /* A status byte, written by the Guest. */
        __u8 status;
        __u8 config[0];
 };
 
-/*D:135 This is how we expect the device configuration field for a virtqueue
- * (type VIRTIO_CONFIG_F_VIRTQUEUE) to be laid out: */
+/*D:135
+ * This is how we expect the device configuration field for a virtqueue
+ * to be laid out in config space.
+ */
 struct lguest_vqconfig {
        /* The number of entries in the virtio_ring */
        __u16 num;
@@ -41,9 +58,16 @@ struct lguest_vqconfig {
 /* Write command first word is a request. */
 enum lguest_req
 {
-       LHREQ_INITIALIZE, /* + base, pfnlimit, pgdir, start */
+       LHREQ_INITIALIZE, /* + base, pfnlimit, start */
        LHREQ_GETDMA, /* No longer used */
        LHREQ_IRQ, /* + irq */
-       LHREQ_BREAK, /* + on/off flag (on blocks until someone does off) */
+       LHREQ_BREAK, /* No longer used */
+       LHREQ_EVENTFD, /* + address, fd. */
 };
+
+/*
+ * The alignment to use between consumer and producer parts of vring.
+ * x86 pagesize for historical reasons.
+ */
+#define LGUEST_VRING_ALIGN     4096
 #endif /* _LINUX_LGUEST_LAUNCHER */