Gcc Debug Bus Error
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Bus Error Core Dumped C Programming
when accessing memory which does not belong to your process, they are very common and are typically the result of: using a pointer to something that was deallocated. using an uninitialized hence bogus pointer. using a null pointer. overflowing a buffer. PS: To be more precise this is not manipulating the pointer itself that will cause issues, it's accessing the memory it points to (dereferencing). share|improve this answer edited Oct 17 '08 at 15:18 answered Oct 17 '08 at 15:12 bltxd 5,72322336 52 They aren't rare; I'm just at Exercise 9 from How to Learn C the Hard Way and already encountered one... –11684 Mar 26 '13 at 20:12 5 Another cause of bus errors (on Linux anyway) is when the operating system can't back a virtual page with physical memory (e.g. low-memory conditions or out of huge pages when using huge page memory.) Typically mmap (and malloc) just reserve the virtual address space, and the kernel assigns the physical memory on demand (so called soft page faults.) Make a large enough malloc, and then write to enough of it and you'll get a bus error. –Eloff Jul 14 '15 at 0:09 add a comment| up vote 58 down vote A segfault is accessing memory that you're not allowed to access. It's read-only, you don't have permission, etc... A bus error is trying to access m
challenged and removed. (July 2015) (Learn how and when to remove this template message) In computing, a bus error is a fault raised by hardware, notifying an operating system (OS) that a process is trying to
How To Solve Bus Error In Linux
access memory that the CPU cannot physically address: an invalid address for the bus error vs segmentation fault address bus, hence the name. In modern use on most architectures these are much rarer than segmentation faults, which occur bus error (core dumped) centos primarily due to memory access violations: problems in the logical address or permissions. On POSIX-compliant platforms, bus errors usually result in the SIGBUS signal being sent to the process that caused the error. SIGBUS http://stackoverflow.com/questions/212466/what-is-a-bus-error can also be caused by any general device fault that the computer detects, though a bus error rarely means that the computer hardware is physically broken—it is normally caused by a bug in a program's source code.[citation needed] Bus errors may also be raised for certain other paging errors; see below. Contents 1 Causes 1.1 Non-existent address 1.2 Unaligned access 1.3 Paging errors 2 Example 3 References Causes[edit] https://en.wikipedia.org/wiki/Bus_error There are at least three main causes of bus errors: Non-existent address[edit] Software instructs the CPU to read or write a specific physical memory address. Accordingly, the CPU sets this physical address on its address bus and requests all other hardware connected to the CPU to respond with the results, if they answer for this specific address. If no other hardware responds, the CPU raises an exception, stating that the requested physical address is unrecognized by the whole computer system. Note that this only covers physical memory addresses. Trying to access an undefined virtual memory address is generally considered to be a segmentation fault rather than a bus error, though if the MMU is separate, the processor can't tell the difference. Unaligned access[edit] Most CPUs are byte-addressable, where each unique memory address refers to an 8-bit byte. Most CPUs can access individual bytes from each memory address, but they generally cannot access larger units (16 bits, 32 bits, 64 bits and so on) without these units being "aligned" to a specific boundary (the x86 platform being a notable exception). For example, if multi-byte accesses must be 16 bit-aligned, addresses (given in bytes) at 0, 2, 4, 6, and so on wou
Login: [x] User account creation filtered due to spam. Bug13906 - genmodes.c:964: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=13906 internal compiler error: Bus error in md5_process_block Summary: genmodes.c:964: internal compiler error: Bus error in md5_process_block Status: RESOLVED FIXED Alias: None Product: gcc Classification: Unclassified Component: http://courses.cms.caltech.edu/cs11/material/c/mike/misc/gdb.html other (show other bugs) Version: 3.4.0 Importance: P2 normal Target Milestone: 3.4.6 Assignee: Not yet assigned to anyone URL: Keywords: build Depends on: Blocks: bus error Reported: 2004-01-28 23:45 UTC by John David Anglin Modified: 2006-02-06 14:07 UTC (History) CC List: 2 users (show) gcc-bugs ghazi See Also: Host: hppa2.0-hp-hpux11.00 Target: hppa2.0-hp-hpux11.00 Build: hppa2.0-hp-hpux11.00 Known to work: Known to fail: Last reconfirmed: 2004-01-29 01:03:40 Attachments Add an attachment (proposed patch, testcase, etc.) Note You need to log in debug bus error before you can comment on or make changes to this bug. Description John David Anglin 2004-01-28 23:45:28 UTC stage1/xgcc -Bstage1/ -B/opt/gnu/gcc/gcc-3.4/hppa2.0w-hp-hpux11.00/bin/ -c -g -O2 -DIN_GCC -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -pedantic -Wno-long-long -Wold-style-definition -Werror -fno-common -DHAVE_CO NFIG_H -DGENERATOR_FILE -I. -I. -I../../gcc/gcc -I../../gcc/gcc/. -I../../gcc /gcc/../include ../../gcc/gcc/genmodes.c -o genmodes.o ../../gcc/gcc/genmodes.c: In function `emit_mode_mask': ../../gcc/gcc/genmodes.c:964: internal compiler error: Bus error The configure command was: ../gcc/configure --with-gnu-as --with-as=/opt/gnu/bin/as --enable-shared --with- local-prefix=/opt/gnu --prefix=/opt/gnu/gcc/gcc-3.4 --enable-debug=no --disable- nls --enable-checking="misc,tree,rtl,rtlflag,gc,gcac,fold" && The problem does not occur if `--enable-checking' is not specified. The stack trace is: Program received signal SIGBUS, Bus error. md5_process_block (buffer=0x7aed3f6e, len=64, ctx=0x7eff1500) at ../../gcc/libiberty/md5.c:325 325 OP (A, B, C, D, 7, (md5_uint32) 0xd76aa478); #0 md5_process_block (buffer=0x7aed3f6e, len=64, ctx=0x7eff1500) at ../../gcc/libiberty/md5.c:325 #1 0x00af0064 in md5_process_bytes (buffer=0x7aed3fae, len=96, ctx=0x7eff1500) at ../../gcc/libiberty/md5.c:239 #2 0x00270b84 in fold_checksum_tree (expr=0x7aed3f00, ctx=0x7eff1500, ht=0x40079aa0) at ../../gcc/gcc/fold-const.c:8408 ... The fault occurs because of a misaligned load for a word: 0x00af0184
manifest themselves in strange ways, such as the program printing interesting messages like "core dump" or "bus error" with no additional information. This is the price you pay for the efficiency and low-level control that the C language provides. Debugging is a big subject, and we can only scratch the surface here. In general, here are three approaches you can use for debugging: When you get a bug, put lots of print statements in code likely to have caused the bug so that you can monitor the values of variables which may not be what they should be. Add lots of assert statements so that when something goes wrong the program halts right away instead of continuing. If you don't know about assert, do "man assert". We will talk more about this later in the course. Use a debugger to find out where your code went wrong. These approaches are not mutually exclusive and almost every programmer uses a combination of all three (plus others). The first two methods are pretty self-explanatory. The third needs a bit more explanation, which we provide below. You can also do "man gdb" and/or "info gdb" to get much more information. GDB basics GDB stands for Gnu DeBugger. It is an environment under which you can run a C program in such a way as to make it very easy to identify bugs. To use gdb, do the following: Compile your program with the -g flag e.g. gcc -Wall -Wstrict-prototypes -ansi -pedantic -g myprog.c -o myprog (Note that we're using a lot of warning options as well, which are the "-Wall -Wstrict-prototypes -ansi -pedantic" options; these force the compiler to complain if your code isn't ANSI-compliant or if it has other suspicious features. It's a good habit to always use these options.) The "-g" option puts debugging information into the executable. Most importantly, it puts the text of the source code file into the executable so you can examine i