Just a quick revisit of native linux kvm tool(nlkt). There were quite a few improvements upstream. So, I git pulled the latest, built kernel; built the binary executable. The nlkt binary is now renamed to ‘lkvm’ (thanks Pekka, it’ll improve searchability a lot)
Some enhancements I noticed from my testing:
– 9pfs enhancements
– Writable support for qcow2 disk-images
– sandbox support — this seems to be mostly a wrapper around ‘run’ command
After building, I posted latest kvm tool binary lkvm, kernel bzImage, linux .config and init binaries over here . Also, a couple of simple test results with latest git.
To try out a slightly long way, clone the nlkt git tree, (also ensure to have the correct directives enabled in the linux config. I posted mine above) ; build the kernel and kvm tool.
Build:
# cd linux-kvm # make -j5 # cd tools/kvm # make
To give a quick try with the binaries I posted above, first let’s setup default rootfs by running the setup command. Note that we also need to have a guest directory with init and init_stage2 binaries. Where the init mounts the host file system as read-only, runs the init_stage2 to setup a tty console and call the shell executable /bin/sh
-------------------------------------------- [kashyap@tesla nlkt-jan11]$ #./lkvm setup default -------------------------------------------- [kashyap@tesla nlkt-jan11]$ pwd /var/tmp/nlkt-jan11 -------------------------------------------- [kashyap@tesla nlkt-jan11]$ tree . ├── bzImage ├── guest │ ├── init │ └── init_stage2 └── lkvm 1 directory, 4 files [kashyap@tesla nlkt-jan11]$
Once we boot into our default rootfs setup, let’s boot into the kernel
[kashyap@tesla nlkt-jan11]$ ./lkvm run -d default # lkvm run -k ./bzImage -m 448 -c 4 --name default . . . Starting '/bin/sh'... sh-4.2#
We can also notice the host file system being mounted read-only in the guest:
-------- sh-4.2# pwd / -------- sh-4.2# ls bin etc host lib64 root sys usr virt dev home lib proc sbin tmp var -------- sh-4.2# ls host/ ; cd host bin dev home lib64 media opt root sbin sys usr boot etc lib lost+found mnt proc run srv tmp var -------- sh-4.2# touch foo touch: cannot touch `foo': Read-only file system sh-4.2# --------
Now, let’s try the sandbox, which will run a command as part of the init and then exits gracefully . In this case, it’s a simple ls command.
-------- [kashyap@tesla nlkt-jan11]$ ./lkvm sandbox -k ./bzImage -- ls # lkvm run -k ./bzImage -m 448 -c 4 --name guest-9990 . . . Mounting... Starting '/bin/sh'... bin etc host lib64 root sys usr virt dev home lib proc sbin tmp var [ 2.052463] Unregister pv shared memory for cpu 1 [ 2.052546] Unregister pv shared memory for cpu 0 [ 2.052578] Unregister pv shared memory for cpu 3 [ 2.055887] Unregister pv shared memory for cpu 2 [ 2.057093] Restarting system. [ 2.057407] machine restart # KVM session ended normally. [kashyap@tesla nlkt-jan11]$ --------
NOTE: I just cleared some of the stdout for brevity.
UPDATE: Pekka Enberg reminded me in a comment below that I missed to note two more additional user-visible features — PPC64 architecture support ; Serial console emulation is much more faster. (I totally agree there.)
Kashyap Chamarthy 