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Consider the following truncated output from running objdump -T (Prints dynamic symbol table entries) on the GNU ls utility.

/usr/bin/ls:     file format elf64-x86-64

DYNAMIC SYMBOL TABLE:
0000000000000000      DF UND  0000000000000000 (GLIBC_2.3)  __ctype_toupper_loc
0000000000000000      DF UND  0000000000000000 (GLIBC_2.2.5) getenv
0000000000000000      DO UND  0000000000000000 (GLIBC_2.2.5) __progname
0000000000000000      DF UND  0000000000000000 (GLIBC_2.2.5) sigprocmask
0000000000000000      DF UND  0000000000000000 (GLIBC_2.3.4) __snprintf_chk
0000000000000000      DF UND  0000000000000000 (GLIBC_2.2.5) raise
0000000000000000      DF UND  0000000000000000 (GLIBC_2.34) __libc_start_main
0000000000000000      DF UND  0000000000000000 (GLIBC_2.2.5) abort
0000000000000000      DF UND  0000000000000000 (GLIBC_2.2.5) __errno_location
0000000000000000      DF UND  0000000000000000 (GLIBC_2.2.5) strncmp
0000000000000000  w   D  UND  0000000000000000  Base        _ITM_deregisterTMCloneTable

What does Base mean in the last line 6th column? For example, It is apparent that (GLIBC_2.2.5) is the glibc version for strncmp function. However, in which external libraries are the Base functions defined? Any pointers in understanding this would be helpful.

Harsh
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1 Answers1

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Base means that there is no version associated with the symbol, i.e. the libraries which provide the symbols don’t provide multiple versions (or in the case of symbols in ls itself, ls contains a single version). The libraries used by ls can be seen using ldd /bin/ls.

See What do the multiple GLIBC versions mean in the output of ldd? for details.

Stephen Kitt
  • 434,908