On Sat, Jun 9, 2012 at 8:01 PM, Adam Lee [off-list ref] wrote:

On Sat, Jun 09, 2012 at 04:19:15PM +0600, Aft nix wrote:

quoted

Thank you for the tips. qemu is booting the kernel now. But it stops
with a kernel panic.

quoted

From qemu console,

[ ? ?2.209887] EXT3-fs (sda): mounted filesystem with writeback data mode
[ ? ?2.210566] VFS: Mounted root (ext3 filesystem) readonly on device 8:0.
[ ? ?2.211393] Freeing unused kernel memory: 456k freed
[ ? ?2.242325] Write protecting the kernel text: 6240k
[ ? ?2.242614] Write protecting the kernel read-only data: 1820k
[ ? ?2.248007] Kernel panic - not syncing: No init found. ?Try passing
init= option to kernel. See Linux Documentation/init.txt for guidance.
[ ? ?2.248492] Pid: 1, comm: swapper/0 Not tainted 3.4.0+ #3
[ ? ?2.248596] Call Trace:
[ ? ?2.249743] ?[<c160db4f>] panic+0x81/0x17e
[ ? ?2.249843] ?[<c10012d5>] init_post+0x75/0xb0
[ ? ?2.249942] ?[<c183a61a>] kernel_init+0x1e0/0x1ea
[ ? ?2.250028] ?[<c183a3df>] ? parse_early_options+0x35/0x35
[ ? ?2.250237] ?[<c183a43a>] ? repair_env_string+0x5b/0x5b
[ ? ?2.250326] ?[<c1616cd6>] kernel_thread_helper+0x6/0xd
...
My understanding is i have to put the init binary in my root fs. But
i'm clueless about how to do that?

You need a full system, kernel is just the core.

I suggest you using Debian stable images for QEMU at
http://people.debian.org/~aurel32/qemu
(ref: http://wiki.debian.org/QEMU)

Or, use busybox to build rootfs like what I am doing:
https://github.com/adam8157/kernel-studio

Hi Adam

Thanks for the reply. Googling revealed other ways of debugging. I was
not aware that KGDB was merged with linux in 2.6.26. I was under the
impression that Linux does not allow kernel debugger in kernel source
tree. If i compile a kernel with KGDB , and if i'm not developing for
"other" archs like ppc/arm then there is little gain in qemu's gdb
stub. Instead i can fire up a full distro in Virtualbox, configure a
virtual serial console and "socat" from the host.

This link : http://www.linuxforu.com/2011/03/kgdb-with-virtualbox-debug-live-kernel/

I'm trying to follow this link instead.

I'm not experienced in this field, so my reasoning might be wrong. If
it is, please comment on my approach.

Cheers.

--
Regards,
Adam Lee
--------------------------------
E-mail: adam8157 at gmail.com
Website: http://adam8157.info
--------------------------------

-- 
-aft