What s the meaning of exception code EXC I386 GPFLT

Question

What s the meaning of exception code EXC I386 GPFLT   Does its meaning vary according to the situation   In that case  I m referring to exception type EXC BAD ACCESS with exception code EXC I386 GPFLT  The program is developed in Xcode 5 0 1  dealing with cblas zgemm   of the BLAS library  Well  I guess it doesn t matter      Thank you very much

User · Answer

You can often get information from the header files. For example:

$ cd /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk
$ find usr -name \*.h -exec fgrep -l EXC_I386_GPFLT {} \;
usr/include/mach/i386/exception.h
^C
$ more usr/include/mach/i386/exception.h
....
#define EXC_I386_GPFLT          13      /* general protection fault     */

OK, so it's a general protection fault (as its name suggests anyway). Googling "i386 general protection fault" yields many hits, but this looks interesting:

Memory protection is also implemented using the segment descriptors. First, the processor checks whether a value loaded in a segment register references a valid descriptor. Then it checks that every linear address calculated actually lies within the segment. Also, the type of access (read, write, or execute) is checked against the information in the segment descriptor. Whenever one of these checks fails, exception (interrupt) 13 (hex 0D) is raised. This exception is called a General Protection Fault (GPF).

That 13 matches what we saw in the header files, so it looks like the same thing. However from the application programmer's point-of-view, it just means we're referencing memory we shouldn't be, and it's doesn't really matter how it's implemented on the hardware.

User · Answer

If the error is thrown inside a closure that defines self as unowned  you may be limited in what you can access and will get this error code in certain situations  Especially while debugging  If this is the case for you try changing  unowned self  to  weak self

User · Answer

I wondered why this appeared during my unit tests   I have added a method declaration to a protocol which included throws  but the potentially throwing method wasn t even used in that particular test  Enabling Zombies in test sounded like too much trouble   Turns out a  K clean did the trick  I m always flabberghasted when that solves actual problems

User · Answer

I m seeing this error code in rotation crashes on Xcode 12 0 Beta 6  only on the iOS 14 simulator  It doesn t crash on my real device running iOS 13 though  So if you re running beta stuff and seeing rotation crashes in the simulator  maybe you just need to run on a real device with a non-beta iOS version

User · Answer

I could get this error working with UnsafeMutablePointer let ptr   rawptr assumingMemoryBound to  A self     lt -- wrong A self Change it to B Self ptr pointee   B

User · Answer

In my case EXC I386 GPFLT was caused by missing return value in the property getter  Like this  -  CppStructure cppStructure       CppStructure data      data a   self alpha      data b   self beta       return data     this line was missing    Xcode 12 2

User · Answer

I got this error while doing this    NSMutableDictionary  aDictionary   NSMutableDictionary alloc  initWithObjectsAndKeys  lt   nonnull id        gt   nil     with 17 objects and keys   It went away when I reverted to   NSMutableDictionary  aDictionary   NSMutableDictionary alloc  init    aDictionary setObject object1 forKey   Key1      17 times

User · Answer

In my case the error was thrown in Xcode when running an app on the iOS simulator  While I cannot answer the specific question  what the error means   I can say what helped me  maybe it also helps others   The solution for me was to Erase All Content and Settings in the simulator and to Clean Build Folder    in Xcode

User · Answer

I had a similar exception at Swift 4 2  I spent around half an hour trying to find a bug in my code  but the issue has gone after closing Xcode and removing derived data folder  Here is the shortcut   rm -rf   Library Developer Xcode DerivedData

User · Answer

This happened to me because Xcode didn t appear to like me using the same variable name in two different classes  that conform to the same protocol  if that matters  although the variable name has nothing related in any protocol   I simply renamed my new variable   I had to step into the setters where it was crashing in order to see it  while debugging  This answer applies to iOS

User · Answer

For me it issue related to storyboard there is option of ViewController build for set iOS 9 0 and later previously set for iOS 10 0 and later  Actually i want to downgrade the ver from 10 to iOS 9 3

User · Answer

I had this issue when leaving a view  pop back to the previous view    the reason was having   addSubview view  view translatesAutoresizingMaskIntoConstraints   false NSLayoutConstraint activate       view leadingAnchor constraint equalTo  safeAreaLayoutGuide leadingAnchor       view topAnchor constraint equalTo  safeAreaLayoutGuide topAnchor       view trailingAnchor constraint equalTo  safeAreaLayoutGuide trailingAnchor       view bottomAnchor constraint equalTo  safeAreaLayoutGuide bottomAnchor       Change safeAreaLayoutGuide to self solve the issue   Meaning aligns the view with the superview s leading  trailing  top  bottom instead of to safe area

User · Answer

EXC I386 GPFLT is surely referring to  General Protection fault   which is the x86 s way to tell you that  you did something that you are not allowed to do   It typically DOESN T mean that you access out of memory bounds  but it could be that your code is going out of bounds and causing bad code data to be used in a way that makes for an protection violation of some sort    Unfortunately it can be hard to figure out exactly what the problem is without more context  there are 27 different causes listed in my AMD64 Programmer s Manual  Vol 2 from 2005 - by all accounts  it is likely that 8 years later would have added a few more    If it is a 64-bit system  a plausible scenario is that your code is using a  non-canonical pointer  - meaning that a 64-bit address is formed in such a way that the upper 16 bits of the address aren t all copies of the top of the lower 48 bits  in other words  the top 16 bits of an address should all be 0 or all 1  based on the bit just below 16 bits   This rule is in place to guarantee that the architecture can  safely expand the number of valid bits in the address range   This would indicate that the code is either overwriting some pointer data with other stuff  or going out of bounds when reading some pointer value    Another likely causes is unaligned access with an SSE register - in other word  reading a 16-byte SSE register from an address that isn t 16-byte aligned    There are  as I said  many other possible reasons  but most of those involve things that  normal  code wouldn t be doing in a 32- or 64-bit OS  such as loading segment registers with invalid selector index or writing to MSR s  model specific registers

User · Answer

To debug and find the source  Enable Zombies for the app  Product Scheme  and Launch Instruments  Select Zombies   Run your app in Xcode Then go to Instruments start recording  Go back to your App and try generating the error   Instruments should detect bad call  to zombie  if there is one   Hope it helps

[c++] What's the meaning of exception code "EXC_I386_GPFLT"?

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