trusty (7) error::buildid.7stap.gz

NAME

       error::buildid - build-id verification failures

DESCRIPTION

       Because  systemtap's script translation / execution stages may be executed at different times and places,
       it is sometimes necessary to verify certain invariants.  One such invariant  is  that  if  a  script  was
       informed  by  translate-time  analysis of executables, then those same executables need to be used at run
       time.   This  checking  is  done  based  upon  the  build-id,  a  binary  hash  that  modern  (post-2007)
       compilers/toolchains add as an NT_GNU_BUILD_ID ELF note to object files and executables.  Use the readelf
       -n command to examine the build-ids of binaries, if you are interested.

       Only scripts are sensitive to executables' build-ids: generally those that perform deep analysis  of  the
       binaries  or  their  debuginfo.   For  example, scripts that place .function or .statement probes, or use
       stack backtrace-related tapset functions may be sensitive.  Other scripts that rely only on  process.mark
       or   kernel.trace   probes   do   not  require  debuginfo.   See  the  DWARF  DEBUGINFO  section  in  the
       stapprobes(3stap) man page.

       During translation, systemtap saves a copy of the relevant files' build-ids within the compiled  modules.
       At  run-time,  the  modules compare the saved ones to the actual run-time build-ids in memory.  The error
       message indicates that they did not match, so the module will decline placing a probe that  was  computed
       based  upon  obsolete  data.   This  is important for safety, as placing them at an inappropriate address
       could crash the programs.  However, this is not necessarily a fatal error, since probes unrelated to  the
       mismatching binaries may operate.

       A  build-id mismatch could be caused by a few different situations.  The main one is where the executable
       versions or architecture were different between the systemtap  translation  and  execution  times/places.
       For  example,  one  may  run  a  stap-server on a slightly different version of the OS distribution.  The
       kernel running on the workstation may be slightly different from the version being targeted - perhaps due
       to  a  pending  kernel  upgrade  leaving  different  files  on disk versus running in memory.  If your OS
       distribution uses separate debuginfo packages, the split .IR .debug files may not exactly match the  main
       binaries.

SEE ALSO

       http://fedoraproject.org/wiki/Releases/FeatureBuildId,             stap(1),            stapprobes(3stap),
       warning::debuginfo(7stap), error::reporting(7stap)

                                                                                           ERROR::BUILDID(7stap)