Contains an image of a 32-bit process at the time of an error.
A core file is created in the current directory when various errors occur. Errors such as memory-address violations, illegal instructions, bus errors, and user-generated quit signals commonly cause this core dump. The core file that is created contains a memory image of the terminated process. A process with a saved user ID that differs from the real user ID does not produce a memory image. The contents of a core dump are organized sequentially in the core file as follows:
The core_dump structure, defined by the core.h file, occurs at the beginning of a core file. The core_dump structure includes the following fields:
| Field Type | Field Name | Description | |
| char | c_signo | The number of the signal that caused the error | |
| char | c_flag | A bit field that describes the core dump type. The meanings of the bits are as follows: | |
| FULL_CORE | core contains the data sections (0x01) | ||
| CORE_VERSION_1 | core was generated by version 4 or higher of the operating system (0x02) | ||
| MSTS_VALID | core contains mstsave structures (0x04) | ||
| CORE_BIGDATA | core contains big data (0x08) | ||
| UBLOCK_VALID | core contains the u_block structure (0x10) | ||
| USTACK_VALID | core contains the user stack (0x20) | ||
| LE_VALID | core contains at least one module (0x40) | ||
| CORE_TRUNC | core was truncated (0x80) | ||
| ushort | c_entries | The number of core dump modules | |
| struct ld_info * | c_tab | The offset to the beginning of the core table | |
| caddr_t | c_stack | The offset to the beginning of the user stack | |
| int | c_size | The size of the user stack | |
| struct mstsave | c_mst | A copy of the faulting mst | |
| struct user | c_u | A copy of the user structure | |
| int | c_nmsts | The number of mstsave structures referenced by the c_msts field | |
| struct mstsave * | c_msts | The offset to the other threads' mstsave structures | |
| int | c_datasize | The size of the data region | |
| caddr_t | c_data | The offset to user data | |
| int | c_vmregions | The number of anonymously mapped regions | |
| struct vm_info * | c_vmm | The offset to the start of the vm_info table | |
The c_u field contains the user structure (a copy of the actual u_block), which includes the registers as they existed at the time of the fault.
The ld_info structure and then the user-mode stack follow the u_block in the core dump.
By default, the user data, anonymously mapped regions, and vm_info structures are not included in a core dump. This partial core dump includes the current thread stack, the thread mstsave structures, the user structures, and the state of the registers at the time of the fault. A partial core dump contains sufficient information for a stack traceback. The size of a core dump can also be limited by the setrlimit subroutine.
To enable a full core dump, set the SA_FULLDUMP flag in the sigaction subroutine for the signal that is to generate a full core dump. If this flag is set when the core is dumped, the data section, anonymously mapped regions, and vm_info structures are included in the core dump.
The param.h file.
The raise subroutine, setrlimit subroutine, setuid subroutine, sigaction subroutine.
The Header Files Overview in AIX Version 4.3 Files Reference defines header files, describes how they are used, and lists several header files for which information is provided in this documentation.