Re: [Xenomai-help] kernel 2.6.32.11 with xenomai 2.5.3 fails to boot on ubuntu lucid system

[Jan Kiszka <jan.kiszka@domain.hid>]

Stefan Kisdaroczi wrote:
> I installed the kernel (2.6.32.15 2.5.4 x86 32bit) which is working on
> my laptop in a kvm machine.
> In the virtual machine the kernel never starts and hangs.

To make sure you are not facing a KVM issue (though they are much rarer
theses days - given you are using a recent KVM version...), please
cross-check if the guest behaves identically when booting without KVM
support (-no-kvm when using qemu-kvm).

> I attached gdb to kvm and according to the cpu registers and system.map
> it hangs in 'doublefault_fn'. As I'm not really familiar with gdb i'm
> thankful if someone has a hint how to proceed. Thanks

Build the kernel with CONFIG_DEBUG_INFO, start "gdb
/linux/src/path/vmlinux", then type "bt" at the gdb prompt when the
guest hangs. This should dump a symbolic backtrace - though likely not
beyond the exception entry. In that case, you could help us by examining
the origin of the exception (parameters to the exception handler, it
specifically receives a full register state).

Also note that there are graphical debuggers, e.g. ddd, that can help
working with gdb without knowing all its commands by heart.

Jan

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