[Vm-dev] Fwd: [Pharo-dev] Pharo 7 Repeatable crash: XIO: fatal IO error 14 (Bad address) on X server ":0"

Martin McClure martin at hand2mouse.com
Mon Feb 26 01:11:43 UTC 2018

On 02/24/2018 01:15 PM, Eliot Miranda wrote:
> Hi Martin,
> On Thu, Feb 22, 2018 at 10:45 AM, Martin McClure
> <martin at hand2mouse.com <mailto:martin at hand2mouse.com>> wrote:
>     Anyone here interested in this crash? Is there a newer VM I should
>     test with?
> Certainly try the most up-to-date Vm you can find.  But this looks
> like some linux-specific, 32-bit specific bug, because no one else is
> reporting crashes like this.  So what I would recommend is that you
> run from the command line under gdb and hence that you would be able
> to get a stack trace, and maybe even dig a little further.  Such a
> crash should be due to something obvious, a null pointer, or a buffer
> overrun.  And running under gdb should allow you to narrow in on the
> bug quite quickly.  If the pharo vm is compiled with symbols then use
> the vm itself, otherwise build your own; you'll need symbols.  If and
> when the bug is easy to reproduce you can switch to the debug vm
> (again you'll have to build it yourself; but builds these days are
> easy; checkout, cd, run a build script) and get more information.
Thanks for the hints.

I can reproduce the problem on the latest VM

The readily-reproducible problem isn't caught by GDB, the VM just exits
out from under GDB after printing

  XIO:  fatal IO error 14 (Bad address) on X server ":0"

But once I did get a segv instead of the usual error and exit. Stack is
below. I don't know when I'll have time to build a debug VM, and don't
know whether it would help given that the reproducible problem isn't
caught by GDB.

Any more hints on how to diagnose?



Reading symbols from ./pharo...done.
(gdb) run ~/apps/Pharo7Builds/2018-02-21/scratch.image
Starting program:
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
[New Thread 0xf7883b40 (LWP 7472)]

Thread 1 "pharo" received signal SIGSEGV, Segmentation fault.
0xf7e7df4f in __memcpy_sse2_unaligned () from /lib32/libc.so.6
(gdb) where
#0  0xf7e7df4f in __memcpy_sse2_unaligned () from /lib32/libc.so.6
#1  0xf7985e01 in NoSwap () from /usr/lib32/libX11.so.6
#2  0xf79867e6 in PutSubImage () from /usr/lib32/libX11.so.6
#3  0xf7985f65 in PutSubImage () from /usr/lib32/libX11.so.6
#4  0xf7986d7a in XPutImage () from /usr/lib32/libX11.so.6
#5  0xf7fc7a40 in stXPutImage (h=<optimized out>, w=0x48c, dst_y=0x0,
dst_x=0x0, src_y=0x0, src_x=0x0, image=0x81ed0a0,
    gc=0x81ea5d8, window=<optimized out>, display=<optimized out>)
#6  display_ioShowDisplay (dispBitsIndex=0xc200010, width=0x490,
height=0x71d, depth=0x20, affectedL=0x0, affectedR=0x48c,
    affectedT=0x0, affectedB=<optimized out>)
#7  0xf7fc312c in redrawDisplay (b=<optimized out>, t=0x0, r=0x48c,
l=<optimized out>)
#8  handleEvent (evt=evt at entry=0xffff415c)
#9  0xf7fc3ffd in handleEvents ()
#10 0xf7fc4a24 in xHandler (fd=fd at entry=0x3, data=0x0,
flags=flags at entry=0x2)
#11 0x080d23cf in aioPoll (microSeconds=microSeconds at entry=0x0)
#12 0x0805efbf in ioProcessEvents () at
#13 0x080958c5 in checkForEventsMayContextSwitch
(mayContextSwitch=<optimized out>)
#14 0x08096f9a in activateCoggedNewMethod
(inInterpreter=inInterpreter at entry=0x0)
#15 0x08097170 in executeNewMethod () at
#16 0x08098b84 in ceSendsupertonumArgs (selector=0x8f8a988,
superNormalBar=0x1, rcvr=0x957d638, numArgs=0x0)
#17 0x082002dc in ?? ()
#18 0x0829d7a4 in ?? ()

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