I am making a setup for kernel debugging over Null modem serial cable , i am trying to make it work on x86 arch machine.I have a straight serial DB9 cable(Having both female ports) which i converted into NULL MODEM CABLE bye doing below rework:
Pin of port #1....goes to....Pin of port #2
2 RxD <-------------> TxD 3
3 TxD <-------------> RxD 2
5 GND <-------------> GND 5
Please check pin connections ones and let me know if i am doing wrong.
I have connected NULL MODEM serial (both female port) cable between two machines via USB to serial coverter cable.I have check the connection between two machine through MINICOM and its works fine.Till this point i didnt face any issue , now lets come to the next point.
1) Download stable kernel 3.4.9 (kernel having inbuilt KGDB support)
2) run make menuconfig command and did the below changes to enable KGDB
a) CONFIG_HAVE_ARCH_KGDB=y
b) CONFIG_KGDB=y
c) CONFIG_KGDB_SERIAL_CONSOLE=y
3) compiled the kernel image successfully
4) make modules
5) make modules_install
6) make install
7) update grub
Below is the grub update detail from grub.cfg file in which i have added following rule for the kernel to wait for the GDB connection establish :
kgdbwait kgdb8250=ttyUSB0,115200,kgdboc=ttyUSB0,115200
menuentry 'Ubuntu, with Linux 3.4.9' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
set gfxpayload=$linux_gfx_mode
insmod part_msdos
insmod ext2
set root='(/dev/sda,msdos1)'
search --no-floppy --fs-uuid --set=root 6ef7b91e-7416-4908-97ba-bfb212081a68
linux /boot/vmlinuz-3.4.9 root=/dev/sda1 ro quiet splash vt.handoff=7 kgdbwait kgdb8250=ttyUSB0,115200,kgdboc=ttyUSB0,115200
}
Booted my machine with the above kernel but i am getting kernel panic not the below message which we expected to get
waiting for gdb connection ........
Please suggest me the right procedure for make this set up work , i am very new to Linux.
Thanks in advance
Thanks
Vivek
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