On 06/29/11 16:14, Apelete Seketeli wrote:

Hello,

I am working on a custom kernel, and I would like to add the necessary
support to enable it to boot with qemu.

When you say "debug inside qemu", do you run
gdb qemu
or
gdb vmlinux

In order to achieve that I am
trying to debug it inside qemu by attaching a gdb to it.

you do this by adding -S -s to the qemu boot parameters.
the from the gdb shell, target remote :1234.
 > I still can't

figure where the boot process is getting stuck with step-by-step
execution, but it seems that the last function called is "delay_loop"
from arch/x86/lib/delay.c.

Have you run the backtrace (bt) command from the gdb shell? That should 
tell you what function is calling the __delay.

That function contains some assembly code, does someone know what it
is supposed to do ?

Probably wait a specific amount of time. Since a compiler optimizes C 
you can't write an accurate delay in C. The compiler wont optimize the 
inline assembly.

Beside, do you have any advice on the way I should proceed to get the
necessary information to port the kernel ?

You should find an existing board and tweak it to get started, or post 
the backtrace output.

Thanks.

Have you had any luck with a google search along the lines of "qemu gdb 
kernel"?