Re: [Kgdb-bugreport] [PATCH][3/3] Update CVS KGDB's wrt connect / detach

[Tom Rini <trini@kernel.crashing.org>]

On Thu, Feb 26, 2004 at 05:57:27PM -0800, George Anzinger wrote:
> Tom Rini wrote:
> >- Connect to a waiting kernel, continue/^C/disconnect/reconnect.
> >- Connect to a running kernel, continue/^C/disconnect/reconnect.
> >- Once connected and running, ^C/hit breakpoint and
> >  disconnect/reconnect.
> >- Once connected, set a breakpoint, kill gdb and hit the breakpoint and
> >  reconnect.
> >- Once connected and running, kill gdb and reconnect.
> >
> >The last two aren't as "fast" as I might like, but they're the "gdb went
> >away in an ungraceful manner" situations, so I think it's OK.  In the
> >first (breakpoint hit, no gdb) I end up having to issue a few continues
> >to get moving again, but it's a one-time event.  
> 
> What are you referring to as "continues".  How is this different from 
> connect to a waiting kernel?   Usually this would be the end of the 
> session.  If you are going to continue from here something needs to be done 
> with the breakpoint that gdb does not know about.  If kgdb can remove them, 
> well fine, except your stopped on one.  If you remove it, there could be 
> some confusion as to why you are in the debugger.  This would be a fine 
> time for a note to the user from kgdb.  It is too bad that the interface 
> does not admit to such a thing.

OK, I've rechecked the senarios, and the only time gdb/kgdb seems a bit
confused is when gdb sets a bpt / dies / bpt is triggered.  It looks
like this (on gdb reattaching to the now stuck host, gdb 6.0):
Remote debugging using /dev/ttyS0
Sending packet: $qPassSignals:0e;10;14;17;1a;1b;1c;21;24;25;4c;#df...Ack
Packet received: 
Packet qPassSignals (pass-signals) is NOT supported
Sending packet: $Hc-1#09...Ack
Packet received: OK
Sending packet: $qC#b4...Ack
Packet received: QC00000000000000d0
Sending packet: $qOffsets#4b...Ack
Packet received: 
Sending packet: $?#3f...Ack

<- At this point, kgdb calls remove_all_break() ->

Packet received: S05
Sending packet: $Hgd0#43...Ack
Packet received: OK
Sending packet: $g#67...Ack
Packet received: 27000000ff0100007b000000c0feffbf703f55d6bc3f55d6c0feffbfd4fdffbf8a4815c08202000060000000680000007b0069d77b000000ffff0000ffff0000
0xc015488a in sys_mkdir (Sending packet: $m27,8#3a...Ack
Packet received: E22
Sending packet: $m27,8#3a...Ack
Packet received: E22
Sending packet: $m27,1#33...Ack
Packet received: E22
Sending packet: $m27,1#33...Ack
Packet received: E22
Sending packet: $m27,1#33...Ack
Packet received: E22
Sending packet: $m27,1#33...Ack
Packet received: E22
pathname=0x27 <Address 0x27 out of bounds>, 
    mode=-1073742144) at fs/namei.c:1533
1533		tmp = getname(pathname);
Sending packet: $qSymbol::#5b...Ack
Packet received: 
Packet qSymbol (symbol-lookup) is NOT supported

<- continue ->

Continuing.
Sending packet: $Hsd0#4f...Ack
Packet received: 
Sending packet: $Hc0#db...Ack
Packet received: OK
Sending packet: $c#63...Ack
Packet received: T0bthread:00000000000000d0;
[New Thread 208]
Sending packet: $g#67...Ack
Packet received: 27000000ff0100007b000000c0feffbf703f55d6bd3f55d6c0feffbfd4fdffbf8b4815c08602010060000000680000007b0069d77b000000ffff0000ffff0000

Program received signal SIGSEGV, Segmentation fault.
0xc015488b in sys_mkdir (Sending packet: $m27,8#3a...Ack
Packet received: E22
Sending packet: $m27,8#3a...Ack
Packet received: E22
Sending packet: $m27,1#33...Ack
Packet received: E22
Sending packet: $m27,1#33...Ack
Packet received: E22
Sending packet: $m27,1#33...Ack
Packet received: E22
Sending packet: $m27,1#33...Ack
Packet received: E22
pathname=0x27 <Address 0x27 out of bounds>, 
    mode=-1073742144) at fs/namei.c:1533
1533		tmp = getname(pathname);

<- continue ->

Continuing.
Sending packet: $C0b#d5...Ack
Packet received: 
Can't send signals to this remote system.  SIGSEGV not sent.
Sending packet: $c#63...Ack
Packet received: T05thread:00000000000000d0;
Sending packet: $g#67...Ack
Packet received: 27000000ff0100007b000000c0feffbf703f55d6bd3f55d6c0feffbfd4fdffbf8b4815c08602010060000000680000007b0069d77b000000ffff0000ffff0000

Program received signal SIGTRAP, Trace/breakpoint trap.
0xc015488b in sys_mkdir (Sending packet: $m27,8#3a...Ack
Packet received: E22
Sending packet: $m27,8#3a...Ack
Packet received: E22
Sending packet: $m27,1#33...Ack
Packet received: E22
Sending packet: $m27,1#33...Ack
Packet received: E22
Sending packet: $m27,1#33...Ack
Packet received: E22
Sending packet: $m27,1#33...Ack
Packet received: E22
pathname=0x27 <Address 0x27 out of bounds>, 
    mode=-1073742144) at fs/namei.c:1533
1533		tmp = getname(pathname);

<- continue ->

Continuing.
Sending packet: $c#63...Ack

<- From here, the system is OK again ->

remote_interrupt called
remote_stop called
Packet received: T05thread:0000000000008000;
[New Thread 32768]
Sending packet: $g#67...Ack
Packet received: 0100000004000000000000000400000068df28c06cdf28c080000000809a28c05afd12c00200000060000000680000007b0010c07b000000ffff0000ffff0000

Program received signal SIGTRAP, Trace/breakpoint trap.
[Switching to Thread 32768]
breakpoint () at kernel/kgdb.c:1088
1088		atomic_set(&kgdb_setting_breakpoint, 0);
Sending packet: $D#44...Ack
Packet received: OK
Ending remote debugging.

-- 
Tom Rini
http://gate.crashing.org/~trini/