[Bug remote/12146] New: GDB 7.2 breaks compatibility from GDB 6.8 with KGDB

[Bug remote/12146] New: GDB 7.2 breaks compatibility from GDB 6.8 with KGDB

[emmanuel.thierry at kerlabs dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12146

           Summary: GDB 7.2 breaks compatibility from GDB 6.8 with KGDB
           Product: gdb
           Version: 7.2
            Status: NEW
          Severity: normal
          Priority: P2
         Component: remote
        AssignedTo: unassigned@sourceware.org
        ReportedBy: emmanuel.thierry@kerlabs.com


Hello,

I use GDB to remotely debug a 2.6.30 linux kernel with KGDB.
When I try to connect to KGDB with a 7.2 version of GDB, packaged by ubuntu, I
get a : "trace API error : 0x2". When I use a 6.8 version, packaged by debian,
I have no problem.

This problem happens on connection, just after having typed "target remote $IP"
or "target remote $DEVICE". It happens either with KGDB over ethernet (kgdboe
driver) and over console (kgdboc embedded driver).

Best regards

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[Bug remote/12146] GDB 7.2 breaks compatibility from GDB 6.8 with KGDB

[pedro at codesourcery dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12146

Pedro Alves <pedro at codesourcery dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |WAITING
                 CC|                            |pedro at codesourcery dot
                   |                            |com

--- Comment #1 from Pedro Alves <pedro at codesourcery dot com> 2010-10-21 10:23:04 UTC ---
Please report this to ubuntu.  ubuntu's gdb has local patches, hence we can't
support it.  (AFAIK, full kgdb support is not present on FSF's gdb.)

That said, if you reproduce the problem with a pristine FSF gdb build, pasting
a "set remote debug 1" log would perhaps help identifying what might have gone
wrong.

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[Bug remote/12146] GDB 7.2 breaks compatibility from GDB 6.8 with KGDB

[emmanuel.thierry at kerlabs dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12146

--- Comment #2 from Emmanuel Thierry <emmanuel.thierry at kerlabs dot com> 2010-10-21 12:17:47 UTC ---
Ok, seams obvious it's better to test with the original source. ;)
I have built gdb 7.2 from the official mirror [
http://ftp.gnu.org/gnu/gdb/gdb-7.2.tar.gz ]. I get the same result :

(gdb) target remote /dev/ttyS0
Remote debugging using /dev/ttyS0
kgdb_breakpoint (new_kgdb_io_ops=0xffffffff80765530) at kernel/kgdb.c:1721
1721        wmb(); /* Sync point after breakpoint */
trace API error 0x2.
(gdb) set remote debug 1
Undefined set remote command: "debug 1".  Try "help set remote".

As you can see, I have no "set remote debug" command. Is there something to
enable in configure ?

Best regards

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[Bug remote/12146] GDB 7.2 breaks compatibility from GDB 6.8 with KGDB

[pedro at codesourcery dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12146

--- Comment #3 from Pedro Alves <pedro at codesourcery dot com> 2010-10-21 13:12:00 UTC ---
Sorry, I make that braino often :-).  It's "set debug remote 1".  And you'll
need to issue it before "target remote" so we can trace the connection.

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[Bug remote/12146] GDB 7.2 breaks compatibility from GDB 6.8 with KGDB

[emmanuel.thierry at kerlabs dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12146

--- Comment #4 from Emmanuel Thierry <emmanuel.thierry at kerlabs dot com> 2010-10-21 13:55:57 UTC ---
It works much better with set debug remote :D
Here is the debug output, some commands look they are no longer supported  :

(gdb) set debug remote 1
(gdb) target remote /dev/ttyS0
Remote debugging using /dev/ttyS0
Sending packet: $qSupported:qRelocInsn+#9a...Ack
Packet received: 
Packet qSupported (supported-packets) is NOT supported
Sending packet: $Hg0#df...Ack
Packet received: OK
Sending packet: $?#3f...Ack
Packet received: S05
Sending packet: $Hc-1#09...Ack
Packet received: OK
Sending packet: $qC#b4...Ack
Packet received: QC00000000000005f8
Sending packet: $qAttached#8f...Ack
Packet received: 
Packet qAttached (query-attached) is NOT supported
Sending packet: $qOffsets#4b...Ack
Packet received: 
Sending packet: $g#67...Ack
Packet received:
420000000000000030557680ffffffffd76b000000000000009002010088ffff4600000000000000e0898580ffffffffc0409c7c0088ffff785ecd7a0088ffff02f4c27d0000000000000000000000000e0000000000000080f4c27d0088ffff402b3e7f0088ffffedffffff00000000c0c63d7f0088ffff00477480ffffffffe0dc2680ffffffff920200001000000018000000
kgdb_breakpoint (new_kgdb_io_ops=0xffffffff80765530) at kernel/kgdb.c:1721
1721        wmb(); /* Sync point after breakpoint */
Sending packet: $qSymbol::#5b...Ack
Packet received: 
Packet qSymbol (symbol-lookup) is NOT supported
Sending packet: $qTStatus#49...Ack
Packet received: E22
trace API error 0x2.

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[Bug remote/12146] GDB 7.2 breaks compatibility from GDB 6.8 with KGDB

[pedro at codesourcery dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12146

Pedro Alves <pedro at codesourcery dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |RESOLVED
         Resolution|                            |INVALID

--- Comment #5 from Pedro Alves <pedro at codesourcery dot com> 2010-10-21 14:07:13 UTC ---
> Packet qSymbol (symbol-lookup) is NOT supported
> Sending packet: $qTStatus#49...Ack
> Packet received: E22
> trace API error 0x2.

Okay, that explains things. This is a kernel bug.  I think I saw this being
fixed recently...  Here it is:

http://kerneltrap.org/mailarchive/linux-kernel/2010/7/22/4596723

You'll need to have that patch in your kernel (or get a newer one that has that
already fixed).

Cheers!

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[Bug remote/12146] GDB 7.2 breaks compatibility from GDB 6.8 with KGDB

[emmanuel.thierry at kerlabs dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12146

--- Comment #6 from Emmanuel Thierry <emmanuel.thierry at kerlabs dot com> 2010-10-21 14:37:19 UTC ---
Ok, thanks, I'll try it. :)

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[Bug remote/12146] GDB 7.2 breaks compatibility from GDB 6.8 with KGDB

[jan.kratochvil at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12146

Jan Kratochvil <jan.kratochvil at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jan.kratochvil at redhat
                   |                            |dot com

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