[Qemu-devel] Failed to use gdb with qemu 15.1 (with and without kvm support)

[Francis Moreau]

Hello,

I'm trying to debug a 64 bits kernel (3.2) using qemu (with and
without KVM support). The host is also 64 bits. Version of gdb I'm
using is 7.1.

To do that I simply start qemu like the following:

 $ qemu-system-x86_64 -kernel bzImage -append "root=/dev/sda1
console=ttyS0 3" -serial stdio -S -s

and in another term, I start gdb like this:

 $ gdb vmlinux
 $ target remote locahost:1234
 $ b prepare_namespace
 $ continue
 Continuing.
 Remote 'g' packet reply is too long: af75919effffffff0.............

So it fails when gdb stops on the breakpoint with the above message.

If I try to dump the backtrace I got:

 $ bt
 Target is executing.
 $ info thread
 * 1 Thread 1 (CPU#0 [running])  (running)

But the VM seems to be stopped because if I'm asking the status to qemu:

 $ info status
 VM status: paused

I also tried qemu with KVM support but I get one more problem: gdb is
ignoring my breakpoint.

Could anybody help me to make gdb work ?

Thanks.
-- 
Francis