1:04 a.m.
Rich,
So, I tried to build the simple supermin app. from your blog. I can confirm that I did get
to the shell when I invoked qemu-kvm.
I used the standard qemu-kvm cmdline (but appended a serial console). This boots fine.
########################################################
[root@moon appliance-test]# qemu-kvm -kernel kernel -append "console=tty0
console=ttyS0,115200" -initrd initrd -hda root -nographic
.
.
.
insmod: error inserting 'ideapad-laptop.ko': -1 Unknown symbol in module
insmod: wait: File exists
febootstrap: insmod sym53c8xx.ko
febootstrap: picked /sys/block/sda/dev as root device
febootstrap: creating /dev/root as block special 8:0
febootstrap: mounting new root on /root
febootstrap: chroot
/proc/uptime: No such file or directory
Welcome to my world
bash: cannot set terminal process group (-1): Inappropriate ioctl for device
bash: no job control in this shell
bash-4.2# [ 1.103034] input: ImExPS/2 Generic Explorer Mouse as
/devices/platform/i8042/serio1/input/input2
[ 1.334183] Refined TSC clocksource calibration: 1995.006 MHz.
bash-4.2#
########################################################
But when I try to 'exit', I notice a kernel panic. And it just seems to hung
there, no
more budging. I had to do 'ctl a + x' to get out of the serial console.
Is this expected?
########################################################
bash-4.2# exit
exit
[ 153.520309] Kernel panic - not syncing: Attempted to kill init!
[ 153.523584] Pid: 1, comm: init Not tainted 2.6.40-4.fc15.x86_64 #1
[ 153.526990] Call Trace:
[ 153.529039] [<ffffffff814ae2cd>] panic+0x91/0x19c
[ 153.531914] [<ffffffff810580a2>] do_exit+0xb9/0x77b
[ 153.534798] [<ffffffff810589e9>] do_group_exit+0x7a/0xa2
[ 153.537835] [<ffffffff81058a28>] sys_exit_group+0x17/0x17
[ 153.540924] [<ffffffff814bd7c2>] system_call_fastpath+0x16/0x1b
########################################################
--
/kashyap
4:01 a.m.
* Kashyap Chamarthy:
So, I tried to build the simple supermin app. from your blog. I can
confirm that I did get to the shell when I invoked qemu-kvm.
I used the standard qemu-kvm cmdline (but appended a serial console). This boots fine.
[...]
But when I try to 'exit', I notice a kernel panic. And it just seems
to hung there, no more budging. I had to do 'ctl a + x' to get out of
the serial console.
Is this expected?
This is normal behavior. The demo system as described by Rich has no
regular init process. The shell has been started via exec, so it is PID
1. PID 1 has a special role on Unix and Linux, the first processs that
is started by the kernel is normally /sbin/init which is responsible for
bringing up the rest of the system. Something must have gone horribly
wrong with the system if this process exits.
And this is what the kernel panic message you posted is all about:
bash-4.2# exit
exit
[ 153.520309] Kernel panic - not syncing: Attempted to kill init!
[ 153.523584] Pid: 1, comm: init Not tainted 2.6.40-4.fc15.x86_64 #1
-Hilko
4:24 a.m.
On Wed, Aug 17, 2011 at 11:34:54AM +0530, Kashyap Chamarthy wrote:
But when I try to 'exit', I notice a kernel panic. And it
just seems
to hung there, no more budging. I had to do 'ctl a + x' to get out
of the serial console.
Is this expected?
As Hilko says, this is normal behaviour when the init process dies:
http://lxr.linux.no/#linux+v3.0.2/kernel/exit.c#L728
In libguestfs, our "init process" is the guestfsd daemon. We
configure the kernel to reboot instead of panicking by adding the
kernel command line option "panic=1".
If you use a real init or systemd then this won't be an issue because
init will issue a reboot system call instead of exiting.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming blog: http://rwmj.wordpress.com
Fedora now supports 80 OCaml packages (the OPEN alternative to F#)
http://cocan.org/getting_started_with_ocaml_on_red_hat_and_fedora
4:30 a.m.
On Wed, Aug 17, 2011 at 10:24:10AM +0100, Richard W.M. Jones wrote:
In libguestfs, our "init process" is the guestfsd daemon.
We
configure the kernel to reboot instead of panicking by adding the
kernel command line option "panic=1".
I should say, we configure the kernel to reboot (panic=1), and qemu to
shutdown on reboot (qemu-kvm -no-reboot).
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines. Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v
6:20 a.m.
On 08/17/2011 03:00 PM, Richard W.M. Jones wrote:
On Wed, Aug 17, 2011 at 10:24:10AM +0100, Richard W.M. Jones wrote:
> In libguestfs, our "init process" is the guestfsd daemon. We
> configure the kernel to reboot instead of panicking by adding the
> kernel command line option "panic=1".
I should say, we configure the kernel to reboot (panic=1), and qemu to
shutdown on reboot (qemu-kvm -no-reboot).
Rich.
Ok, so , If I have to build appliance which has a bunch of %post, %preun, %postun, %pre
operations in it's RPM SPEC file, I need to pull all of those into a custom init
script(like the one for libguestfs[1]), so that the guest kernel can detect this(run it as
PID 1) and sanely bring up the rest of the system ?
And then I need to invoke 'febootstrap-supermin-helper' like below to build the
appliance.
# febootstrap-supermin-helper -f ext2 supermin.d x86_64 kernel initrd appliance.
Where appliance is the file system. As of now, other file systems like ext3/ext4(maybe
btrfs in future) are not yet available ?
Question: After I build and boot the appliance, how about networking inside it? Any
pointers to that?
Thank Rich and Hilko. I need to wrap my head a little bit more around this and try a few
more things.
Ref:
[1] http://git.annexia.org/?p=libguestfs.git;a=blob;f=appliance/init;hb=HEAD
--
/kashyap
7:02 a.m.
On Wed, Aug 17, 2011 at 04:50:17PM +0530, Kashyap Chamarthy wrote:
Ok, so , If I have to build appliance which has a bunch of %post,
%preun, %postun, %pre operations in it's RPM SPEC file, I need to
pull all of those into a custom init script(like the one for
libguestfs[1]), so that the guest kernel can detect this(run it as
PID 1) and sanely bring up the rest of the system ?
Yes, you're gonna need an /init file anyway.
Another unfortunate thing about Fedora is that the base RPMs like
"filesystem-*.rpm" don't contain all the base files. If you look at
the source for mock, anaconda and so on, you'll see some code to
create the base system. For example:
https://fedorahosted.org/mock/browser/py/mock/backend.py#L385
Naturally this duplicated code is slightly different in each program
where it appears.
So your /init file should probably create some basic filesystem and
device nodes as in the mock example above, then include any bits from
the %pre/%post scripts that look important, and then jump to whichever
init system you want (eg. /sbin/init which in newer Fedora is a link
to systemd).
And then I need to invoke 'febootstrap-supermin-helper' like
below to build the appliance.
# febootstrap-supermin-helper -f ext2 supermin.d x86_64 kernel initrd appliance.
Where appliance is the file system. As of now, other file systems
like ext3/ext4(maybe btrfs in future) are not yet available ?
It would be very simple to modify febootstrap to support ext3 and/or
ext4. (btrfs would definitely NOT be a simple change). In libguestfs
the appliance is added read-only with a disposable overlay on top.
Thus journals (a data integrity feature) don't make any sense for us.
http://git.annexia.org/?p=libguestfs.git;a=blob;f=src/launch.c;h=e58add54...
Question: After I build and boot the appliance, how about networking
inside it? Any pointers to that?
You just need to pass the right parameters to qemu. Assuming you are
using a real init system, the network will be brought up automatically
inside the guest when it detects the virtual hardware.
http://git.annexia.org/?p=libguestfs.git;a=blob;f=src/launch.c;h=e58add54...
Note also that you can overlay any extra files (eg. config files,
programs) that you need in the appliance by dropping cpio files into
the supermin.d directory. Again, take a look at how libguestfs does it:
http://git.annexia.org/?p=libguestfs.git;a=tree;f=appliance;hb=HEAD
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines. Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v
8:43 a.m.
On 08/17/2011 05:32 PM, Richard W.M. Jones wrote:
On Wed, Aug 17, 2011 at 04:50:17PM +0530, Kashyap Chamarthy wrote:
> Ok, so , If I have to build appliance which has a bunch of %post,
> %preun, %postun, %pre operations in it's RPM SPEC file, I need to
> pull all of those into a custom init script(like the one for
> libguestfs[1]), so that the guest kernel can detect this(run it as
> PID 1) and sanely bring up the rest of the system ?
Yes, you're gonna need an /init file anyway.
Another unfortunate thing about Fedora is that the base RPMs like
"filesystem-*.rpm" don't contain all the base files. If you look at
the source for mock, anaconda and so on, you'll see some code to
create the base system. For example:
https://fedorahosted.org/mock/browser/py/mock/backend.py#L385
Naturally this duplicated code is slightly different in each program
where it appears.
So your /init file should probably create some basic filesystem and
device nodes as in the mock example above, then include any bits from
the %pre/%post scripts that look important, and then jump to whichever
init system you want (eg. /sbin/init which in newer Fedora is a link
to systemd).
Thanks Rich, for this great detail. I haven't played much with mock, apart from
building a
couple of packages(I understand that everything is done in 'chroot'). I need to
take a
closer look at mock source and play around more a little bit.
> And then I need to invoke 'febootstrap-supermin-helper' like below to build
the appliance.
>
> # febootstrap-supermin-helper -f ext2 supermin.d x86_64 kernel initrd appliance.
>
> Where appliance is the file system. As of now, other file systems
> like ext3/ext4(maybe btrfs in future) are not yet available ?
It would be very simple to modify febootstrap to support ext3 and/or
ext4. (btrfs would definitely NOT be a simple change). In libguestfs
the appliance is added read-only with a disposable overlay on top.
Thus journals (a data integrity feature) don't make any sense for us.
If it's trivial to add newest ext* fs, that's nice. For projects we'd like to
build
appliances, there will be decent I/O ( maybe the newest available journaling FS may
help..)
http://git.annexia.org/?p=libguestfs.git;a=blob;f=src/launch.c;h=e58add54...
> Question: After I build and boot the appliance, how about networking
> inside it? Any pointers to that?
You just need to pass the right parameters to qemu. Assuming you are
using a real init system, the network will be brought up automatically
inside the guest when it detects the virtual hardware.
Ah, that makes sense, so using all the regular networking parameters to qemu would do the
trick
http://git.annexia.org/?p=libguestfs.git;a=blob;f=src/launch.c;h=e58add54...
Note also that you can overlay any extra files (eg. config files,
programs) that you need in the appliance by dropping cpio files into
the supermin.d directory. Again, take a look at how libguestfs does it:
http://git.annexia.org/?p=libguestfs.git;a=tree;f=appliance;hb=HEAD
Thanks again for all the detail.
Rich.
--
/kashyap
8:57 a.m.
On Wed, Aug 17, 2011 at 07:13:19PM +0530, Kashyap Chamarthy wrote:
On 08/17/2011 05:32 PM, Richard W.M. Jones wrote:
>It would be very simple to modify febootstrap to support ext3 and/or
>ext4. (btrfs would definitely NOT be a simple change). In libguestfs
>the appliance is added read-only with a disposable overlay on top.
>Thus journals (a data integrity feature) don't make any sense for us.
If it's trivial to add newest ext* fs, that's nice. For projects
we'd like to build appliances, there will be decent I/O ( maybe the
newest available journaling FS may help..)
I'm a bit busy now, but patches welcome. Basically it involves
changing the command line argument processing a bit, and passing the
'-t {ext2,ext3,ext4}' flag through to mke2fs. And testing that it
still works. See the febootstrap.git helper/ subdirectory,
particularly 'main.c' and 'ext2.c'.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines. Supports shell scripting,
bindings from many languages. http://libguestfs.org
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7 comments
3 participants
participants (3)
-
Hilko Bengen -
Kashyap Chamarthy -
Richard W.M. Jones