289d1054e9
After commit 07fe997, lguest tool has already moved from
Documentation/virtual/lguest/ to tools/lguest/.
Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
126 lines
4.3 KiB
Plaintext
126 lines
4.3 KiB
Plaintext
__
|
|
(___()'`; Rusty's Remarkably Unreliable Guide to Lguest
|
|
/, /` - or, A Young Coder's Illustrated Hypervisor
|
|
\\"--\\ http://lguest.ozlabs.org
|
|
|
|
Lguest is designed to be a minimal 32-bit x86 hypervisor for the Linux kernel,
|
|
for Linux developers and users to experiment with virtualization with the
|
|
minimum of complexity. Nonetheless, it should have sufficient features to
|
|
make it useful for specific tasks, and, of course, you are encouraged to fork
|
|
and enhance it (see drivers/lguest/README).
|
|
|
|
Features:
|
|
|
|
- Kernel module which runs in a normal kernel.
|
|
- Simple I/O model for communication.
|
|
- Simple program to create new guests.
|
|
- Logo contains cute puppies: http://lguest.ozlabs.org
|
|
|
|
Developer features:
|
|
|
|
- Fun to hack on.
|
|
- No ABI: being tied to a specific kernel anyway, you can change anything.
|
|
- Many opportunities for improvement or feature implementation.
|
|
|
|
Running Lguest:
|
|
|
|
- The easiest way to run lguest is to use same kernel as guest and host.
|
|
You can configure them differently, but usually it's easiest not to.
|
|
|
|
You will need to configure your kernel with the following options:
|
|
|
|
"Processor type and features":
|
|
"Paravirtualized guest support" = Y
|
|
"Lguest guest support" = Y
|
|
"High Memory Support" = off/4GB
|
|
"Alignment value to which kernel should be aligned" = 0x100000
|
|
(CONFIG_PARAVIRT=y, CONFIG_LGUEST_GUEST=y, CONFIG_HIGHMEM64G=n and
|
|
CONFIG_PHYSICAL_ALIGN=0x100000)
|
|
|
|
"Device Drivers":
|
|
"Block devices"
|
|
"Virtio block driver" = M/Y
|
|
"Network device support"
|
|
"Universal TUN/TAP device driver support" = M/Y
|
|
"Virtio network driver" = M/Y
|
|
(CONFIG_VIRTIO_BLK=m, CONFIG_VIRTIO_NET=m and CONFIG_TUN=m)
|
|
|
|
"Virtualization"
|
|
"Linux hypervisor example code" = M/Y
|
|
(CONFIG_LGUEST=m)
|
|
|
|
- A tool called "lguest" is available in this directory: type "make"
|
|
to build it. If you didn't build your kernel in-tree, use "make
|
|
O=<builddir>".
|
|
|
|
- Create or find a root disk image. There are several useful ones
|
|
around, such as the xm-test tiny root image at
|
|
http://xm-test.xensource.com/ramdisks/initrd-1.1-i386.img
|
|
|
|
For more serious work, I usually use a distribution ISO image and
|
|
install it under qemu, then make multiple copies:
|
|
|
|
dd if=/dev/zero of=rootfile bs=1M count=2048
|
|
qemu -cdrom image.iso -hda rootfile -net user -net nic -boot d
|
|
|
|
Make sure that you install a getty on /dev/hvc0 if you want to log in on the
|
|
console!
|
|
|
|
- "modprobe lg" if you built it as a module.
|
|
|
|
- Run an lguest as root:
|
|
|
|
tools/lguest/lguest 64 vmlinux --tunnet=192.168.19.1 \
|
|
--block=rootfile root=/dev/vda
|
|
|
|
Explanation:
|
|
64: the amount of memory to use, in MB.
|
|
|
|
vmlinux: the kernel image found in the top of your build directory. You
|
|
can also use a standard bzImage.
|
|
|
|
--tunnet=192.168.19.1: configures a "tap" device for networking with this
|
|
IP address.
|
|
|
|
--block=rootfile: a file or block device which becomes /dev/vda
|
|
inside the guest.
|
|
|
|
root=/dev/vda: this (and anything else on the command line) are
|
|
kernel boot parameters.
|
|
|
|
- Configuring networking. I usually have the host masquerade, using
|
|
"iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE" and "echo 1 >
|
|
/proc/sys/net/ipv4/ip_forward". In this example, I would configure
|
|
eth0 inside the guest at 192.168.19.2.
|
|
|
|
Another method is to bridge the tap device to an external interface
|
|
using --tunnet=bridge:<bridgename>, and perhaps run dhcp on the guest
|
|
to obtain an IP address. The bridge needs to be configured first:
|
|
this option simply adds the tap interface to it.
|
|
|
|
A simple example on my system:
|
|
|
|
ifconfig eth0 0.0.0.0
|
|
brctl addbr lg0
|
|
ifconfig lg0 up
|
|
brctl addif lg0 eth0
|
|
dhclient lg0
|
|
|
|
Then use --tunnet=bridge:lg0 when launching the guest.
|
|
|
|
See:
|
|
|
|
http://www.linuxfoundation.org/collaborate/workgroups/networking/bridge
|
|
|
|
for general information on how to get bridging to work.
|
|
|
|
- Random number generation. Using the --rng option will provide a
|
|
/dev/hwrng in the guest that will read from the host's /dev/random.
|
|
Use this option in conjunction with rng-tools (see ../hw_random.txt)
|
|
to provide entropy to the guest kernel's /dev/random.
|
|
|
|
There is a helpful mailing list at http://ozlabs.org/mailman/listinfo/lguest
|
|
|
|
Good luck!
|
|
Rusty Russell rusty@rustcorp.com.au.
|