Can't attach using 2 Machine Debugging
Can't attach using 2 Machine Debugging
- Subject: Can't attach using 2 Machine Debugging
- From: Michael Cashwell <email@hidden>
- Date: Thu, 14 Nov 2002 19:22:41 -0500
Greeting,
I've been having fits trying to get gdb to work in a 2 machine setup so
I can interactively debug my KNE. I've read all the docs I can find
(tn2063 and Hello Debugger [revved on 1Nov!]) but am still getting
nowhere.
I'm running "6.2 Darwin Kernel Version 6.2: Tue Nov 5 22:00:03 PST
2002; root:xnu/xnu-344.12.2.obj~1/RELEASE_PPC" on both a Tibook (dev)
and a Pismo G3 (target). I've done the incantations to get the
permanent arp entry and using file sharing copied the .sym file from
kextload -s to the dev system and have set the boot-args to
"debug=0xe". On the dev system I have:
[Mikes-Tibook:~] cashwell% sudo arp -s 10.0.0.10 0:3:93:3:4b:92
[Mikes-Tibook:~] cashwell% arp -a
? (10.0.0.10) at 0:3:93:3:4b:92 permanent
? (224.0.0.251) at 1:0:5e:0:0:fb permanent
? (239.255.255.253) at 1:0:5e:7f:ff:fd permanent
I then trigger the panic on the target. It spews text on the screen
ending with the correct MAC and IP addresses and claims to be waiting
for a remote debugger connection. Nothing else ever happens on the
target's display.
I then do the normal:
[Mikes-Tibook:~] cashwell% gdb /mach_kernel
...
(gdb) add-symbol-file com.company.kext.myshim.sym
add symbol table from file "com. company.kext.myshim.sym" at
(y or n) y
Reading symbols from /Users/cashwell/com.company.kext.myshim.sym...done.
(gdb) target remote-kdp
(gdb) attach 10.0.0.10
and then get 10 repetitions of error messages:
kdp_reply_wait: error from kdp_receive: receive timeout exceeded
kdp_transaction (remote_connect): transation timed out
kdp_transaction (remote_connect): re-sending transaction
and
kdp_transaction (remote_connect): host not responding; will retry
unable to connect to host "10.0.0.10": receive timeout exceeded
If I try it with a non-existent IP address it ends slightly differently:
kdp_transmit_fd: sendto returns -1: Host is down (64)
unable to connect to host "10.0.0.44": RR_IP_ERROR
so it looks like the permanent route is having some effect.
This is the first time I've needed to do 2 machine debugging for a very
long time and I did just update to 10.2.2. Can anyone confirm that it
still works?
I saw a worrisome comment in an Apple doc for the meaning of the
boot-arg flags. It says debug flag 0x10 is to "Make ddb (kdb) the
default debugger (requires a custom kernel)."
I don't have that flag set as the docs say to use 0xe. Yet the gdb
command the docs say to use is "target remote-kdb".
Which is right?
One last datum, my target machine does have 2 ethernet interfaces
active (one wired and one Airport). I need the latter so an app running
on another platform can trigger the panic. But I'm using the wired
interface for debugging (or trying to). Could having both enabled be
messing things up even thought the panic spew lists the addresses of
the wired interface?
Wondering if it was the Pismo's Ethernet hardware I tried another
TiBook as the target machine but it acted identically.
Any ideas would be appreciated.
Thanks,
Mike
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