Linux Bus Error
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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 linux bus error (core dumped) to access memory that the CPU cannot physically address: an invalid address for
How To Solve Bus Error In Linux
the address bus, hence the name. In modern use on most architectures these are much rarer than segmentation faults, which bus error in c occur 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
How To Debug Bus Error
error. SIGBUS 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 sigbus error linux 3 References Causes[edit] 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
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Bus Error Vs Segmentation Fault
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Bus Error 10 Mac
Stack Overflow Community Stack Overflow is a community of 6.2 million programmers, just like you, helping each other. Join them; it only takes a bus error ubuntu minute: Sign up What is a bus error? up vote 156 down vote favorite 49 What does the "bus error" message mean, and how does it differ from a segfault? c unix segmentation-fault bus-error share|improve this question edited Oct 18 '15 https://en.wikipedia.org/wiki/Bus_error at 10:44 Cool Guy 15.7k51952 asked Oct 17 '08 at 14:48 raldi 7,272216178 add a comment| 15 Answers 15 active oldest votes up vote 151 down vote accepted Bus errors are rare nowadays on x86 and occur when your processor cannot even attempt the memory access requested, typically: using a processor instruction with an address that does not satisfy its alignment requirements. Segmentation faults occur when accessing memory which does not belong to your process, they are very common and are typically the http://stackoverflow.com/questions/212466/what-is-a-bus-error 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 memory that can't possibly be there. You've used an address that's meaningless to the system, or the wrong kind of address for that operation. share|improve this answer answered Oct 17 '08 at 14:55 Clinton Pierce 6,9189
Start here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company http://serverfault.com/questions/456337/server-responds-bus-error-to-every-command Business Learn more about hiring developers or posting ads with us Server Fault Questions Tags Users Badges Unanswered Ask Question _ Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute: Sign up Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top Server responds “bus error” to every command up bus error vote 4 down vote favorite I have a linux machine dedicated to MySQL server with a pretty high load. Today I woke up and was terrified to see that database server is down. I could connect to it via SSH, but it was responding with bus error to each and every command: [root@r1304 home]# ls Bus error [root@r1304 home]# tail /var/log/messages Bus error [root@r1304 home]# reboot Bus error [root@r1304 home]# free -m Bus error [root@r1304 linux bus error home]# chkdisk Bus error I went to Data Center and did a hard reset, which seemed to help, but after a half an hour situation reapeated and now I can't even connet via SSH anymore. Any ideas what this could be? how to diagnose such a problem and what are possible fixes? Server has 32 GB RAM, 2xSSD drives with software RAID UPDATE According to Zabbix, when MySQL died, number of processes stated to increase drammaticaly, until I did a hard reset. What could those be? Number of processes linux centos hardware ssd bus share|improve this question edited Jul 24 '14 at 20:09 msanford 1,2251224 asked Dec 8 '12 at 13:30 Temnovit 31241224 Those are processes piling up waiting for I/O. Something is happening at the storage layer. –ewwhite Dec 8 '12 at 23:47 What was the issue? –ewwhite Dec 10 '12 at 10:32 @ewwhite, well, the hard drive completely died. Hello, kingston SSD. I'm bying a new one and restoring from a backup. –Temnovit Dec 10 '12 at 19:41 add a comment| 1 Answer 1 active oldest votes up vote 6 down vote accepted Your storage system seems to have failed. You can't read from disk at this point. Can you see the messages in the kernel ring buffer? Look at the output of dmesg i