Malformed response to offset query, qOffsets

[Shamir Rabinovitch <shamir dot rabinovitch at gmail dot com>]

My setup is as follow:

Host Setup
---------------
* Distribution = Ubuntu 12.04 LTS
* Kernel = 3.2.0-31-generic-pae #50-Ubuntu SMP Fri Sep 7 16:39:45 UTC
2012 i686 i686 i386 GNU/Linux
* GDB = GNU gdb (Ubuntu/Linaro 7.4-2012.04-0ubuntu2) 7.4-2012.04

Virtual Box
----------------
* Oracle VM VirtualBox Manager 4.1.12_Ubuntu
* Guest Serial = COM1 IRQ4 PORT 0x3F8
* Host Serial = named pipe
* Command to pipe the serial to PTS on host = socat -d -d /tmp/vbox_serial pty
* Serial PTY on host = /dev/pts/3

Guest Setup
-----------------
* Distribution = Ubuntu 12.04 LTS
* Kernel = 3.6.0-rc3+ #2 SMP Tue Aug 2822:58:29IDT 2012 i686 i686 i386 GNU/Linux
* Serial = ttyS0,9600n8
* Kernel Options:
** CONFIG_HAVE_ARCH_KGDB=y
** CONFIG_KGDB=y
** CONFIG_KGDB_SERIAL_CONSOLE=y


When I attach the debugger I see the GDB is able to communicate with
the guest but after some short exchange between the host GDB and the
guest I get the error.

Any idea why the GDB report this error & how to work this issue?

Many thanks, Shamir

**********************************************************************************

eden@eden-desktop:/tftpboot$ gdb ./vmlinux
GNU gdb (Ubuntu/Linaro 7.4-2012.04-0ubuntu2) 7.4-2012.04
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i686-linux-gnu".
For bug reporting instructions, please see:
<http://bugs.launchpad.net/gdb-linaro/>...
Reading symbols from /tftpboot/vmlinux...done.
(gdb) set debug remote 1
(gdb) set remotebaud 9600
(gdb) target remote /dev/pts/3
Remote debugging using /dev/pts/3
Sending packet:
$qSupported:multiprocess+;xmlRegisters=i386;qRelocInsn+#b5...putpkt:
Junk: IRQ sharing enabled
[    0.848401] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[    0.877932] 00:05: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[    0.878888] Non
Nak
Sending packet:
$qSupported:multiprocess+;xmlRegisters=i386;qRelocInsn+#b5...putpkt:
Junk: volatile memory driver v1.3
[    0.879409] Linux agpgart interface v0.103
[    0.880089] [drm] Initialized drm 1.1.0 20060810
[    0.882360] brd: module loaded
[    0.883790] loop: module lneed, doesn't support DPO or FUA
[   68.238073] scsi 1:0:0:0: CD
Nak
Sending packet:
$qSupported:multiprocess+;xmlRegisters=i386;qRelocInsn+#b5...putpkt:
Junk: ROM            VBOX     CD
Nak
Sending packet:
$qSupported:multiprocess+;xmlRegisters=i386;qRelocInsn+#b5...putpkt:
Junk: ROM           1.0  PQ: 0 ANSI: 5
[   68.285574]  sda: sda1 sda2 < sda5 >
[   68.288798] e1000 0000:00:03.0: eth0: (PCI:33MHz:32
Nak
Packet received: qSupported:multiprocess+;xmlRegisters=i386;qRelocInsn+
Packet qSupported (supported-packets) is supported
Sending packet: $Hg0#df...Packet instead of Ack, ignoring it
Packet instead of Ack, ignoring it
Packet instead of Ack, ignoring it
putpkt: Junk: Loading, please wait...
mount: mounting udev on /dev failed: No such device
W: devtmpfs not available, falling back to tmpfs for /dev

Ack
Packet received: Hg0
Sending packet: $?#3f...Ack
Packet received: ?
Sending packet: $Hc-1#09...Ack
Packet received: Hc-1
Sending packet: $qC#b4...Ack
Packet received: qC
Sending packet: $qAttached#8f...Ack
Packet received: qAttached
Packet qAttached (query-attached) is supported
Sending packet: $qOffsets#4b...Ack
Packet received: qOffsets
Malformed response to offset query, qOffsets