[Libguestfs] Using guestfs to debug kernel

[Teto]

Thanks for the detailed answer. I will try the second one.
>Hope that is of some help.
That really helps :)

Matt

2013/12/3 Richard W.M. Jones <rjones at redhat.com>:
> On Tue, Dec 03, 2013 at 06:05:24PM +0100, Teto wrote:
>> Hi,
>>
>> I would like to use libguestfs to help me setup a VM that I run later
>> with qemu to debug my linux kernel (via qemu -kernel <mykernel>
>> -append ...).
>> One problem I face for instance is that my VM lacks the modules
>> matching my kernel version. So what would you consider as the best
>> option here to load the modules for the kernel ?
>> Should I upload the modules from the host to the VM /lib/modules (need
>> to tar this fodler and upload it via tar_in ?!) ? Or can I access my
>> /lib/modules over the network via a specific initramfs ?
>>
>> I am quite open to any suggestion, I've already got the libguestfs
>> python binding working.
>
> A couple of ideas:
>
> (1) Keep /lib/modules on a separate virtual disk (mounted in the guest
> using /etc/fstab or an early init script), so you only have to rebuild
> that disk when your kernel changes.  You can use guestfish or
> virt-make-fs to rebuild the virtual disk (relatively) quickly.
>
>   virt-make-fs /lib/modules/`uname -r` modules.img
>
> takes 11.2 seconds (warmed up) on my machine.
>
> (2) Use 9p to export the /lib/modules directory from the host into the
> guest.  http://wiki.qemu.org/Documentation/9psetup has instructions
> how to do this.  This way you don't need to build any modules disk at
> all, but you will need to compile 9p into your test kernel and have an
> init script that mounts the 9p disk quite early in the boot process
> (before any modules are needed).
>
> Hope that is of some help.
>
> Rich.
>
> --
> Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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