Linux Kernel  3.7.1
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lguest_launcher.h
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1 #ifndef _LINUX_LGUEST_LAUNCHER
2 #define _LINUX_LGUEST_LAUNCHER
3 /* Everything the "lguest" userspace program needs to know. */
4 #include <linux/types.h>
5 
6 /*D:010
7  * Drivers
8  *
9  * The Guest needs devices to do anything useful. Since we don't let it touch
10  * real devices (think of the damage it could do!) we provide virtual devices.
11  * We could emulate a PCI bus with various devices on it, but that is a fairly
12  * complex burden for the Host and suboptimal for the Guest, so we have our own
13  * simple lguest bus and we use "virtio" drivers. These drivers need a set of
14  * routines from us which will actually do the virtual I/O, but they handle all
15  * the net/block/console stuff themselves. This means that if we want to add
16  * a new device, we simply need to write a new virtio driver and create support
17  * for it in the Launcher: this code won't need to change.
18  *
19  * Virtio devices are also used by kvm, so we can simply reuse their optimized
20  * device drivers. And one day when everyone uses virtio, my plan will be
21  * complete. Bwahahahah!
22  *
23  * Devices are described by a simplified ID, a status byte, and some "config"
24  * bytes which describe this device's configuration. This is placed by the
25  * Launcher just above the top of physical memory:
26  */
28  /* The device type: console, network, disk etc. Type 0 terminates. */
30  /* The number of virtqueues (first in config array) */
32  /*
33  * The number of bytes of feature bits. Multiply by 2: one for host
34  * features and one for Guest acknowledgements.
35  */
37  /* The number of bytes of the config array after virtqueues. */
39  /* A status byte, written by the Guest. */
42 };
43 
44 /*D:135
45  * This is how we expect the device configuration field for a virtqueue
46  * to be laid out in config space.
47  */
49  /* The number of entries in the virtio_ring */
51  /* The interrupt we get when something happens. */
53  /* The page number of the virtio ring for this device. */
55 };
56 /*:*/
57 
58 /* Write command first word is a request. */
60 {
61  LHREQ_INITIALIZE, /* + base, pfnlimit, start */
62  LHREQ_GETDMA, /* No longer used */
63  LHREQ_IRQ, /* + irq */
64  LHREQ_BREAK, /* No longer used */
65  LHREQ_EVENTFD, /* + address, fd. */
66 };
67 
68 /*
69  * The alignment to use between consumer and producer parts of vring.
70  * x86 pagesize for historical reasons.
71  */
72 #define LGUEST_VRING_ALIGN 4096
73 #endif /* _LINUX_LGUEST_LAUNCHER */