Re: debugging symbols and gdb

[Patrick Welche <prlw1%cam.ac.uk@localhost>]

On Tue, Jan 08, 2019 at 05:51:40PM +0000, Patrick Welche wrote:
> On Fri, Jan 04, 2019 at 10:28:56PM +0700, Robert Elz wrote:
> >     Date:        Fri, 4 Jan 2019 10:43:52 +0000
> >     From:        Patrick Welche <prlw1%cam.ac.uk@localhost>
> >     Message-ID:  <20190104104352.GC611@quark>
> > 
> >   | I can try that as well, but my point is that I have them - file
> >   | shows that they are built in, gdb says it loaded them. That no
> >   | function of Xorg appears named in the backtrace is unlikely.
> > 
> > Purely a guess, as I have no idea how it works ir is supposed to
> > work, but do you have ASLR (sysctl security.pax.aslr.enabled)
> > enabled?
> 
> I have now:
> - set security.pax.aslr.enabled=0 in /etc/sysctl.conf
> - built with MKDEBUG
> - ssh into the laptop, gdb `which X`, attach to /usr/X11R7/bin/X process
> - login via xdm, and finally some symbols:

Same system, and

# gdb `which Xorg` X.core
GNU gdb (GDB) 8.0.1
...
Reading symbols from /usr/X11R7/bin/Xorg...Reading symbols from /usr/libdata/debug//usr/X11R7/bin/Xorg.debug...done.
...
Program terminated with signal SIGBUS, Bus error.
#0  0x00007f7fed6ad3e5 in ?? ()
[Current thread is 1 (process 1)]
(gdb) bt
#0  0x00007f7fed6ad3e5 in ?? ()
#1  0x00007f7ff3599900 in ?? ()
#2  0x0000010100020037 in ?? ()
#3  0x00007f7ff7bd13c0 in ?? ()
#4  0x0000000000000100 in ?? ()
#5  0x0300020001000000 in ?? ()
#6  0x00007f7ff400759a in ?? ()
#7  0x0b000a0009000800 in ?? ()
#8  0x00007f7fffffdeb8 in ?? ()
#9  0x00007f7fffffdeb0 in ?? ()
#10 0x00007f7fffffdea6 in ?? ()
#11 0x1b001a0019001800 in ?? ()
#12 0x1f001e001d001c00 in ?? ()
#13 0x2300220021002000 in ?? ()
#14 0x2700260025002400 in ?? ()
#15 0x2b002a0029002800 in ?? ()
#16 0x00007f7ff355b140 in ?? ()
#17 0x00007f7ff35090e0 in ?? ()
#18 0x0000000d00000011 in ?? ()
#19 0x20003a0039003800 in ?? ()
#20 0x0000000000000000 in ?? ()