tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 * Devices are described by a simplified ID, a status byte, and some "config"
20 * bytes which describe this device's configuration. This is placed by the
21 * Launcher just above the top of physical memory:
22 */
23struct lguest_device_desc {
24 /* The device type: console, network, disk etc. Type 0 terminates. */
25 __u8 type;
26 /* The number of virtqueues (first in config array) */
27 __u8 num_vq;
28 /* The number of bytes of feature bits. Multiply by 2: one for host
29 * features and one for guest acknowledgements. */
30 __u8 feature_len;
31 /* The number of bytes of the config array after virtqueues. */
32 __u8 config_len;
33 /* A status byte, written by the Guest. */
34 __u8 status;
35 __u8 config[0];
36};
37
38/*D:135 This is how we expect the device configuration field for a virtqueue
39 * to be laid out in config space. */
40struct lguest_vqconfig {
41 /* The number of entries in the virtio_ring */
42 __u16 num;
43 /* The interrupt we get when something happens. */
44 __u16 irq;
45 /* The page number of the virtio ring for this device. */
46 __u32 pfn;
47};
48/*:*/
49
50/* Write command first word is a request. */
51enum lguest_req
52{
53 LHREQ_INITIALIZE, /* + base, pfnlimit, pgdir, start */
54 LHREQ_GETDMA, /* No longer used */
55 LHREQ_IRQ, /* + irq */
56 LHREQ_BREAK, /* + on/off flag (on blocks until someone does off) */
57};
58#endif /* _LINUX_LGUEST_LAUNCHER */