error::pass4.7stap man page

error::pass4 — systemtap pass-4 errors

Description

Errors that occur during pass 4 (compilation) have generally only a few causes:

kernel or OS version changes

The systemtap runtime and embedded-C fragments in the tapset library are designed to be portable across a wide range of OS versions.  However, incompatibilities can occur when some OS changes occur, such as kernel modifications that change functions, types, or macros referenced  by systemtap.  Upstream (git://sourceware.org/git/systemtap.git) builds of systemtap are often quickly updated to include relevant fixes, so try getting or making an updated build.  Reworded: build systemtap from git for use with very young kernels. If the issue persists, report the problem to the systemtap developers.

buggy embedded-C code

Embedded-C code in your own guru-mode script cannot be checked by systemtap, and is passed through verbatim to the compiler.  Errors in such snippets of code may be found during the pass-4 compiler invocation, though may be hard to identify by the compiler errors.

incompatible embedded-C code

The interface standards between systemtap-generated code and embedded-C code occasionally change.  For example, before version 1.8, arguments were passed using macros THIS->foo and THIS->__retvalue but from version 1.8 onward, using STAP_ARG_foo and STAP_RETVALUE. Adjust your embedded-C code to current standards, or use the stap --compatible=VERSION option to make systemtap use a different one.

compiler bugs and mysteries

Messages such as "internal compiler error" suggest compiler problems.  These should be reported to the compiler developers in the form of a preprocessed .i file, plus the compiler command line.  To gather relevant information, run

stap -k --vp 0003 -p4 ....

Systemtap will report the saved temporary directory, and the compiler command line it attempted.  Go to the directory to find he main generated file stap_NNNNN_src.c. Force the compiler to produce a preprocessed file with:

make -C /lib/modules/`uname -r`/build M=`pwd` stap_NNNNN_src.i

(note the .i suffix), and the compiler command line should be in the file .stap_NNNNN_src.i.cmd.

See Also

stap(1),
error::reporting(7stap)