Re: kgdb 2.3 hangs

On Mon, 2006-01-30 at 12:26 +0530, Amit Kale wrote:
> Tom, Ming,
> 
> module debugging patch uses read memory packets, so it won't have any smp 
> issues.
> 
> Have you passed "nmi_watchdog=1" to kernel through grub.conf file? Please 
> also 
> check the output of dmesg, to confirm that NMI watchdog in deed works. If it 
> doesn't you'll see a message in dmesg output. If nmi_watchdog=1 doesn't work 
> try nmi_watchdog=2. (Yeah, seems like a joke, but that's exactly what it 
> is :-)

yes, i knew this nmi trick, it is funny.

> 
> I see two different issues here.
> 
> 1. You could go ahead after turning off console messages over kgdb. This 
> should be required. I would like to see a dump of packets with this option 
> turned on. We'll get some idea about why this option is causing a problem.

i selected it, compiled, and loaded the new kernel. got this.

----------------------------
This GDB was configured as "i686-pc-linux-gnu"...
(gdb) set remotebaud 57600
(gdb) set debug remote 1
(gdb) set solib-search-path /root/kgdb/module26
(gdb) target remote /dev/ttyS0
Remote debugging using /dev/ttyS0
Sending packet: $Hc-1#09...Ack
Packet received: OK
Sending packet: $qC#b4...Ack
Packet received: QC0000000000008000
Sending packet: $qOffsets#4b...Ack
Packet received:
Sending packet: $?#3f...Ack
Packet received: S05
Sending packet: $Hg8000#77...Ack
Packet received: OK
Sending packet: $g#67...Ack
Packet received:
01000000c01a64c000000000728362c0209f60c0249f60c07b8362c042f762c
08bbf14c08600000060000000680000007b0000007b000000ffff0000ffff0000
breakpoint () at kernel/kgdb.c:1776
1776            atomic_set(&kgdb_setting_breakpoint, 0);
Sending packet: $mc0566328,4#9e...Packet instead of Ack, ignoring it
Packet instead of Ack, ignoring it
Packet instead of Ack, ignoring it
Packet instead of Ack, ignoring it
Packet instead of Ack, ignoring it
Bad checksum, sentsum=0xd1, csum=0x9b, buf=28356c0
Packet instead of Ack, ignoring it
Packet instead of Ack, ignoring it
Bad checksum, sentsum=0xd1, csum=0x9b, buf=28356c0
Packet instead of Ack, ignoring it
Packet instead of Ack, ignoring it
Bad checksum, sentsum=0xd1, csum=0x9b, buf=28356c0
Packet instead of Ack, ignoring it
Packet instead of Ack, ignoring it
Bad checksum, sentsum=0xd1, csum=0x9b, buf=28356c0
Packet instead of Ack, ignoring it
putpkt: Junk: 286356c0#d1
----------------------------

then after a while, saw this. seems that serial link is broken


Sending packet: $mc0566328,4#9e...putpkt: write failed: Input/output
error.

(gdb) c
Continuing.
Sending packet: $Z0,c014bc80,1#38...putpkt: write failed: Input/output
error.
(gdb) c
Continuing.
Sending packet: $Z0,c014bc80,1#38...putpkt: write failed: Input/output
error.


> 
> I have seen a bug report earlier where console message packets got mixed up 
> with regular gdb packets, don't know how. Couldn't reproduce it later. I 
> think we should print a message from kgdb indicating that smp isn't working. 
> Perhaps halt kernel at that point.
> 
> 2. The output you have sent is rather limited. Could you send the _whole_ 
> output. That is right from the point where gdb prints it's initial version 
> no. etc. to the point where debugging fails.
> 
> -Amit
> 
> On Friday 27 Jan 2006 9:12 pm, Ming Zhang wrote:
> > On Fri, 2006-01-27 at 08:31 -0700, Tom Rini wrote:
> > > On Fri, Jan 27, 2006 at 10:12:46AM -0500, Ming Zhang wrote:
> > > > thanks for the hint.
> > > >
> > > > now i deselect the "console message over kgdb" and use this 'set debug
> > > > remote 1', the boot process is good.
> > > >
> > > >
> > > > now is another problem.
> > > >
> > > > it hangs when loading module.
> > >
> > > You need to have a custom compiled GDB with the patches found in CVS,
> > > if you've also got the 'module.patch' patch applied.
> >
> > i run the gdb_mod 2.3 from download page. i assumed that is the one you
> > mentioned.
> >
> > > But I'll admit I haven't tested module autoloading stuff on SMP, but it
> > > should work.
> >
> > though i am using a dual opteron, i already disabled SMP and choose P4
> > for a 32bit compilation.
> >
> > ming
> >
> >
> >
> >
> >
> >
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