Dear All / Spiro,<br><br> I tried setting up KGDB on my machine but somehow I am not
finding my luck for past few months. <br> Sprio. in his earlier mail had said about his success of setting up KGDB, Can you please share your notes of
how to set up KGDB. If possibe please share the screen shots. Let me
feel happy about the gdb prompt.<br>
<br>Following is my set up.<br><br>I have two x86 single core machines. C1 and C2.<br>C1 = target<br>C2 = Host<br><br>On Target I have built a custom kernel 2.6.34 with KGDB enabled. Here is the snapshot of my .config<br>
CONFIG_MAGIC_SYSRQ=y<br>CONFIG_DEBUG_INFO=y<br>CONFIG_HAVE_ARCH_KGDB=y<br>CONFIG_KGDB=y<br>CONFIG_KGDB_SERIAL_CONSOLE=y<br><br>My vmlinux is around 65MB.<br><br><b>Scenario 1:</b><br><br>I
connected a null modem cable from C1 to C2. Tested the cable by
redirecting the kernel boot logs from C1 to C2 thru the cable and cable
is fine.<br>
I connected C1 to a LCD monitor (console=tty0) through a VGA cable so
that I used tty0 to view normal kernel booting logs and null modem cable
to work with debugger<br><br>My grub.conf is <br><br>title Fedora (2.6.34)<br> root (hd0,1)<br>
kernel /vmlinuz-2.6.34 ro
root=UUID=4a51e22e-ec12-469f-80ff-17afe3e6f15f rd_NO_LUKS rd_NO_LVM
rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYTABLE=us
<br> console=tty0 kgdbwait <code>kgdb8250=ttyS0,115200</code><br><br> initrd /initramfs-2.6.34.img<br>
<br>
<b>The result was, on booting up the kernel kgdb was not waiting. </b><br>
<br>
<b>Scenario 2. <br>
<br>
</b>I connected a null modem cable from C1 to C2. Tested the cable by
redirecting the kernel boot logs from C1 to C2 thru the cable and cable is fine.<br>
I connected C1 to a LCD monitor (console=tty0) through a VGA cable so
that I tty0 to view normal kernel booting logs and null modem cable to
work with debugger<br>
<br>
My grub.conf is <br>
<br>
title Fedora (2.6.34)<br>
root (hd0,1)<br>
kernel /vmlinuz-2.6.34 ro
root=UUID=4a51e22e-ec12-469f-80ff-17afe3e6f15f rd_NO_LUKS rd_NO_LVM
rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYTABLE=us
<br>
console=tty0 kgdbwait <code>kgdboc=ttyS0,115200<br>
</code> initrd /initramfs-2.6.34.img<br>
<br>
<b>The result is, on booting up the kernel kgdb is waiting for the input
( This log was seen on my LCD monitor) but Alt-SysRq-g did not work
here to switch to the debugger<br>
</b><br>
<b>Scenario 3:</b><br>
<br>
I connected a null modem cable from C1 to C2. Tested the cable by
redirecting the kernel boot logs from C1 to C2 thru the cable and cable is fine.<br>
<br>
My grub.conf is <br>
<br>
title Fedora (2.6.34)<br>
root (hd0,1)<br>
kernel /vmlinuz-2.6.34 ro
root=UUID=4a51e22e-ec12-469f-80ff-17afe3e6f15f rd_NO_LUKS rd_NO_LVM
rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYTABLE=us
<br>
console=ttyS0,115200n8 kgdbwait <code>kgdboc=ttyS0,115200 kgdbcon<br>
</code> initrd /initramfs-2.6.34.img<br>
<br>
<b>
The result is, on booting up the kernel kgdb is waiting for the input (
This log was seen on my minicom console) but Alt-SysRq-g did not work
and it threw some garbage. </b><br>
<br>
On the host side I executed the following commands. <br>
<br>
<pre><font size="4"># gdb ./vmlinux
(gdb) set remotebaud 115200
(gdb) target remote /dev/ttyS0<br></font><font size="4"><br>Some of the documents say that after executing the last command I should see the gdb prompt from where I can set breakpoints, single stepping, but didn't show up for me :(<br>
<br><br><b>Note:</b> If it really matters. I was working on my host machine through a putty session. <br><br>Request you or anyone to bail me out from the clutches of this precarious problem.<br><br><br>Thanks,<br>Prabhu<br>
</font></pre>