re: bin/53891: sandy bridge i965 SNA bus error

[matthew green <mrg%eterna.com.au@localhost>]

The following reply was made to PR bin/53891; it has been noted by GNATS.

From: matthew green <mrg%eterna.com.au@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, prlw1%cam.ac.uk@localhost
Subject: re: bin/53891: sandy bridge i965 SNA bus error
Date: Fri, 25 Jan 2019 05:29:32 +1100

 >  As mrg enabled backtrace -> log, here is another example - 0x12 is an
 >  interesting address...
 
 pity that libbacktrace's unwinder can't cope beyond signals:
 
 >  [   240.916] (**) Option "XkbRules" "base"
 >  [   240.916] (**) Option "XkbModel" "pc105"
 >  [   240.916] (**) Option "XkbLayout" "us"
 >  [   240.916] (II) XINPUT: Adding extended input device "<default keyboa=
 rd>" (type: KEYBOARD, id 7)
 >  [   245.830] (EE) =
 
 >  [   245.830] (EE) Backtrace:
 >  [   245.836] (EE) 0: /usr/X11R7/bin/X (xorg_backtrace+0x3d) [0x3b37d3]
 >  [   245.836] (EE) 1: /usr/X11R7/bin/X (os_move_fd+0x67) [0x3af9f9]
 >  [   245.836] (EE) 2: /usr/lib/libc.so.12 (__sigtramp_siginfo_2+0x0) [0x=
 7f7ff32a9ac0]
 >  [   245.836] (EE) =
 
 >  [   245.836] (EE) Segmentation fault at address 0x12
 >  [   245.836] (EE) =
 
 >  Fatal server error:
 >  [   245.836] (EE) Caught signal 11 (Segmentation fault). Server abortin=
 g
 
 so all really 0x12 means is that someone tried to access a struct member
 that is at offset 0x12 but using a NULL pointer.  however, as we don't
 have the stack trace beyond the signal, don't know what it was.  ie, my
 enabling of backtrace doesn't help the main problem i hoped for.