Linux Map System

Description of the System.map file under Linux. This page is a mirror of Peter Jay Salzman's System.map Explanation, and the only modification made by me is the addition of this note. --rworkman The system.map File. There seems to be a dearth of information about the System.map file. It's really nothing mysterious, and in the scheme of things

In Linux, the System.map file is a symbol table used by the kernel. A symbol table is a look-up between symbol names and their addresses in memory. A symbol name may be the name of a variable or the name of a function. The System.map is required when the address of a symbol name, or the symbol name of an address, is needed.

But the System.map shows all virtual addresses. How can I know the physical address of myptr? In previous baremetal programas, I could see the memory using the map file it showed the physical address, virtualphysical, but in this case the System.map shows virtual addresses which I can't localize..

as far as i understand it, the System.map file contains the locations of all the functions active in the compiled kernel. the file can be named using versions - like System.map-2.4.5 or whatever version you happen to have.

System.map contains a symbol table, i.e. a list of function names in the Linux kernel, with for each function the address at which its code is loaded in memory the addresses are not physical addresses, they're in the kernel's address space, like any executable symbol table is in the loaded process address space.This isn't limited to system calls the interfaces exposed to user processes

In Linux, the .mw-parser-output .monospacedfont-familymonospace,monospaceSystem.map file is a symbol table used by the kernel. A symbol table is a look-up between symbol names and their addresses in memory. A symbol name may be the name of a variable or the name of a function. The System.map is required when the address of a symbol name, or the symbol name of an address, is needed.

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It indicates to the kernel virtual memory system that the mapping should extend downward in memory. The return address is one page lower than the memory area that is actually created in the process's virtual address space. Before Linux 2.6.7, the MAP_POPULATE flag has effect only if prot is specified as PROT_NONE. SUSv3 specifies that mmap

quotSystem.mapquot. is a file produced via nm containing symbol names and addresses of the linux kernel binary, vmlinux. Its primary use is in debugging. If a kernel quotoopsquot message appears, the utility ksymoops can be used to decode the message into something useful for developers. ksymoops makes use of the System.map to map PC values to symbolic

Apparently, not only does klogd look for the correct version of the map in the 3 klogd search directories, but klogd also knows to look for the name quotSystem.mapquot followed by quot-kernelversionquot, like System.map-2.4.18. This is undocumented feature of klogd.