lguest.txt update

o Describe the new split configurations
o Highlight code documentation in drivers/lguest/README
o Point out necessity of having a getty on /dev/hvc0
o Remove gratuitous "m" in example
o Don't discuss I/O model here, stick to user documentation.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2007-10-22 10:56:23 +10:00
parent 141341cdae
commit 9653c4aff9

View File

@ -6,7 +6,7 @@ Lguest is designed to be a minimal 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.
encouraged to fork and enhance it (see drivers/lguest/README).
Features:
@ -23,19 +23,30 @@ Developer features:
Running Lguest:
- Lguest runs the same kernel as guest and host. You can configure
them differently, but usually it's easiest not to.
- 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:
CONFIG_HIGHMEM64G=n ("High Memory Support" "64GB")[1]
CONFIG_TUN=y/m ("Universal TUN/TAP device driver support")
CONFIG_EXPERIMENTAL=y ("Prompt for development and/or incomplete code/drivers")
CONFIG_PARAVIRT=y ("Paravirtualization support (EXPERIMENTAL)")
CONFIG_LGUEST=y/m ("Linux hypervisor example code")
"General setup":
"Prompt for development and/or incomplete code/drivers" = Y
(CONFIG_EXPERIMENTAL=y)
and I recommend:
CONFIG_HZ=100 ("Timer frequency")[2]
"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":
"Network device support"
"Universal TUN/TAP device driver support" = M/Y
(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
@ -51,14 +62,17 @@ Running Lguest:
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:
Documentation/lguest/lguest 64m vmlinux --tunnet=192.168.19.1 --block=rootfile root=/dev/lgba
Documentation/lguest/lguest 64 vmlinux --tunnet=192.168.19.1 --block=rootfile root=/dev/lgba
Explanation:
64m: the amount of memory to use.
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.
@ -99,31 +113,7 @@ Running Lguest:
"--sharenet=<filename>": any two guests using the same file are on
the same network. This file is created if it does not exist.
Lguest I/O model:
There is a helpful mailing list at http://ozlabs.org/mailman/listinfo/lguest
Lguest uses a simplified DMA model plus shared memory for I/O. Guests
can communicate with each other if they share underlying memory
(usually by the lguest program mmaping the same file), but they can
use any non-shared memory to communicate with the lguest process.
Guests can register DMA buffers at any key (must be a valid physical
address) using the LHCALL_BIND_DMA(key, dmabufs, num<<8|irq)
hypercall. "dmabufs" is the physical address of an array of "num"
"struct lguest_dma": each contains a used_len, and an array of
physical addresses and lengths. When a transfer occurs, the
"used_len" field of one of the buffers which has used_len 0 will be
set to the length transferred and the irq will fire.
Using an irq value of 0 unbinds the dma buffers.
To send DMA, the LHCALL_SEND_DMA(key, dma_physaddr) hypercall is used,
and the bytes used is written to the used_len field. This can be 0 if
noone else has bound a DMA buffer to that key or some other error.
DMA buffers bound by the same guest are ignored.
Cheers!
Good luck!
Rusty Russell rusty@rustcorp.com.au.
[1] These are on various places on the TODO list, waiting for you to
get annoyed enough at the limitation to fix it.
[2] Lguest is not yet tickless when idle. See [1].