gdb 7.5 BFD unknown load command & Unable to find Mach task port

[jb_duffy@…]

Hi

Mountain Lion OS X 10.8.2, XCode 4.5.1, MacBook Pro 2.4 GHz Intel Core i7, 4 GB 1333 MHz DDR3

I have successfully installed MacPorts gcc-mp-4.7. And, gdb 7.5 appears to have installed successfully. I can build a simple Hello World C program but when I try to debug it with gdb I get one possibly two separate errors.

Below is a sample build and debug session:

macbook:test john$ make
gcc-mp-4.7 -Wall -std=c99 -pedantic -g -O0 hello.c -o hello
macbook:test john$ ls -l
total 40
-rw-r--r--  1 john  staff    69 25 Oct 15:20 Makefile
-rwxr-xr-x  1 john  staff  8756 25 Oct 15:22 hello
-rw-r--r--  1 john  staff   110 25 Oct 15:22 hello.c
drwxr-xr-x  3 john  staff   102 25 Oct 15:22 hello.dSYM
macbook:test john$ ggdb hello
GNU gdb (GDB) 7.5
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-apple-darwin12.2.0".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
BFD: /Users/john/test/hello: unknown load command 0x2a
BFD: /Users/john/test/hello: unknown load command 0x28
BFD: /Users/john/test/hello: unknown load command 0x2b
BFD: /Users/john/test/hello: unknown load command 0x2a
BFD: /Users/john/test/hello: unknown load command 0x28
BFD: /Users/john/test/hello: unknown load command 0x2b
Reading symbols from /Users/john/test/hello...Reading symbols from /Users/john/test/hello.dSYM/Contents/Resources/DWARF/hello...done.
done.
(gdb) l 1
1	#include <stdio.h>
2	#include <stdlib.h>
3	
4	int main(void)
5	{
6	  printf("Hello, World!\n");
7	  exit(EXIT_SUCCESS);
8	}
(gdb) b 6
Breakpoint 1 at 0x100000f62: file hello.c, line 6.
(gdb) r
Starting program: /Users/john/test/hello 
Unable to find Mach task port for process-id 77680: (os/kern) failure (0x5).
 (please check gdb is codesigned - see taskgated(8))
(gdb) quit

Any help would be greatly appreciated with the BFD error and guidance on how to solve the code signing issue.

Regards

John

[mf2k (Frank Schima)]

In the future, please Cc the port maintainer(s).

[lpsinger (Leo Singer)]

Cc Me!

[evandrix (Lee Wei Yeong)]

Cc Me!

[ldalessandro@…]

Cc Me!

[maligree@…]

Cc Me!

[maligree@…]

Has anyone had any luck with this? I'm willing to dive into this one to get it work and come up with a clear answer, but I don't want to reinvent the wheel.

[jb_duffy@…]

Replying to maligree@…:

Has anyone had any luck with this? I'm willing to dive into this one to get it work and come up with a clear answer, but I don't want to reinvent the wheel.

I'm not aware of any luck with this. I would help but I don't have the technical skills. I'm very happy to help out testing etc.

[jdswinbank (John Swinbank)]

Cc Me!

[jdswinbank (John Swinbank)]

​http://sourceware.org/gdb/wiki/BuildingOnDarwin explains how to generate a certificate and sign the gdb executable, and, indeed, signing the gdb executable installed by Macports following those instructions solves the issue for me. I'm not sure how easy it would be to automate within the Macports infrastructure, though.

[dave@…]

Interesting; codesigning doesn't solve the problem for me. My /usr/bin/gdb works, but my /opt/local/bin/ggdb doesn't. The only differences I can see are in the files' extended attributes:

cube:/tmp/bld/modhist/debug dave% codesign --verify --verbose $(which gdb) $(which ggdb)
/usr/bin/gdb: valid on disk
/usr/bin/gdb: satisfies its Designated Requirement
/opt/local/bin/ggdb: valid on disk
/opt/local/bin/ggdb: satisfies its Designated Requirement
cube:/tmp/bld/modhist/debug dave% ls -l@ $(which gdb) $(which ggdb)      
-rwxr-sr-x  1 root  wheel  5206576 Jan 10 10:53 /opt/local/bin/ggdb
-rwxr-xr-x@ 1 root  wheel    11032 Nov 27 14:29 /usr/bin/gdb
	com.apple.cs.CodeDirectory	    112 
	com.apple.cs.CodeRequirements	     80 
	com.apple.cs.CodeSignature	   1346 

However, I don't know how to produce those attributes on ggdb, nor do I know what the correct numbers would be.

[karl.smeltzer@…]

Cc Me!

[thomas.fanghaenel@…]

Same issue here. I have code-signed the executable, but am still getting the "Unable to find Mach task port" error when I try to run the executable in gdb.

bash-3.2$ ~/local/bin/gdb a.out
GNU gdb (GDB) 7.5.50.20130115
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-apple-darwin11.4.2".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /Users/xxx/tmp/a.out...Reading symbols from /Users/xxx/tmp/a.out.dSYM/Contents/Resources/DWARF/a.out...done.
done.
(gdb) break main
Breakpoint 1 at 0x100000f0b: file foo.c, line 5.
(gdb) run
Starting program: /Users/xxx/tmp/a.out 
Unable to find Mach task port for process-id 70913: (os/kern) failure (0x5).
 (please check gdb is codesigned - see taskgated(8))
(gdb) 

Here's the information that I get back from codesign on the executable:

bash-3.2$ codesign -d -v ~/local/bin/gdb
Executable=/Users/xxx/local/bin/gdb
Identifier=org.gnu.gdb
Format=Mach-O thin (x86_64)
CodeDirectory v=20100 size=31400 flags=0x0(none) hashes=1565+2 location=embedded
Signature size=1605
Signed Time=Jan 15, 2013 1:24:47 PM
Info.plist entries=4
Sealed Resources=none
Internal requirements count=1 size=88

The only difference I can see between the default gdb executable and the one I built are, as Dave pointed out, the extra permissions. Any pointers anybody?

[thomas.fanghaenel@…]

Cc Me!

[jdegenhardt@…]

Cc Me!

[ltalirz (Leopold Talirz)]

Cc Me!

[cooljeanius (Eric Gallager)]

If codesigning failed to work, did you try modifiying the launchd plist for taskgated as described in #39349 and port notes gdb? Also does this still happen with gdb 7.6?

[cooljeanius (Eric Gallager)]

Cc Me!

[mf2k (Frank Schima)]

dweber has retired. See #43834.

[stuartwesterman (Stuart Westerman)]

This can be fixed by setting the -p in the taskgated plist:

/System/Library/LaunchDaemons/com.apple.taskgated.plist

            <key>ProgramArguments</key>
            <array>
                    <string>/usr/libexec/taskgated</string>
                    <string>-sp</string>
            </array>

This is not a problem. Please close.

[plinss (Peter Linss)]

Having the same issue with El Capitan and GDB @7.9.1_3+python34 (MacPorts 2.3.4).

I have turned off System Integrity Protection and added the 'p' argument to taskgated as above (and rebooted) and still get: Unable to find Mach task port for process-id 537: (os/kern) failure (0x5).

(please check gdb is codesigned - see taskgated(8))

[malaperle@…]

I was able to make it work on El Capitan by following ​https://sourceware.org/gdb/wiki/BuildingOnDarwin *then* changing the group of ggdb from procmon to admin, so

sudo chgrp admin /opt/local/bin/ggdb

[malaperle@…]

Patch that removes the chgrp to procmon and links to the new instructions

[mf2k (Frank Schima)]

#53744

[raimue (Rainer Müller)]

gdb notes hint at codesigning as of [380ef99dde4cec0516cba66797d478ff0d97239d/macports-ports] (#54217).