.\" t
.TH ERROR::PASS4 7stap 
.SH NAME
error::pass4 \- systemtap pass-4 errors

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

.TP
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: \fBbuild systemtap from git
for use with very young kernels\fP.
If the issue persists, report the problem to the systemtap developers.

.TP
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.

.TP
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
.IR THIS->foo " and " THIS->__retvalue
but from version 1.8 onward, using
.IR STAP_ARG_foo " and " STAP_RETVALUE "."
Adjust your embedded-C code to current standards, or use the
.IR "stap --compatible=VERSION"
option to make systemtap use a different one.

.TP
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
.IR ".i"
file, plus the compiler command line.  To gather relevant information, run
.SAMPLE
stap -k --vp 0003 -p4 ....
.ESAMPLE
Systemtap will report the saved temporary directory, and the compiler
command line it attempted.  Go to the directory to find he main generated
file
.IR stap_NNNNN_src.c .
Force the compiler to produce a preprocessed file with:
.SAMPLE
make -C /lib/modules/`uname -r`/build M=`pwd` stap_NNNNN_src.i
.ESAMPLE
(note the
.IR .i
suffix), and the compiler command line should be in the file
.IR ".stap_NNNNN_src.i.cmd" .

.SH SEE ALSO
.nh
.nf
.IR stap (1),
.IR error::reporting (7stap)