Incomprehensible app crash on old iPod/iPhone

1
votes

I have a strange app crash:

  • it crashes on iPod 2G (iOS 4.2) and iPhone 3G (iOS 3.1.3) but runs well on iPhone 4, iPad and Simulator
  • it crashes each time in the same line with "EXC_BAD_INSTRUCTION" (some little time after app launching)
  • it crashes at calling system functions: first time at alListenerf(...), then if I comment this line it crashes at mmap(...), and after commenting it at glBindFramebufferOES(...), executing well my code between these functions

I profiled the app with Instruments thinking that the problem is with memory but there is enough free memory on device at the moment of crash. Earlier I met a similar crash on release build related to "level of optimization" setting (crash on "Fast" and "Faster", works on "None") but now it crashes in debug and release builds. Looks like there is a device-specific bug.

Maybe someone has solved the same problem, I should be thankful for help.

1
iphonecrash
Given where this is crashing (memory-constrained devices and lines of code that deal with memory access), it really does sound like a memory problem of some sort. Are you using the Memory Monitor instrument to determine that you are below the hard-kill line on those older devices? Just having free memory on the device doesn't mean that the system won't kill your application if it crosses a certain threshold. - Brad Larson
is glBindFramebufferOES a OpenGL ES function? OpenGL ES is only supported on iPhone 3GS and iPod touch 3G and later. - ughoavgfhw
@ughoavgfhw - That is incorrect. glBindFramebufferOES() is OpenGL ES 1.1, which is supported on all iOS devices, even the older ones. If it was glBindFramebuffer(), that's OpenGL ES 2.0, which is only available on iPhone 3G S and newer devices. - Brad Larson
Brad Larson, please look at Instruments measurements: Memory Monitor->Real memory: 4.59Mb (of my app process), Memory Used: 73Mb, Memory Free: 8.45Mb; Allocations->Live/Overall Bytes: 261Kb. Maybe 73Mb of used memory causes the crash (but I measured another well-running app - 76Mb used)? - brigadir
The Real Memory usage of the application (running on the older device where it crashes) is what's key. As long as that's below 30 MB (the hard ceiling for older devices), you should be good. Total memory used in the entire system shouldn't matter that much, as long as there is some free memory. Are these figures from the time at which the application crashes on the older device? - Brad Larson

1 Answers

1
votes

Make sure you're generating instructions for both arm6 and arm7 processors. The older phones don't understand the newer arm7 instruction set.