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Diffstat (limited to 'stapprobes.5.in')
| -rw-r--r-- | stapprobes.5.in | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/stapprobes.5.in b/stapprobes.5.in index d05d35c0..f1744d2f 100644 --- a/stapprobes.5.in +++ b/stapprobes.5.in @@ -25,15 +25,19 @@ The general probe point syntax is a dotted-symbol sequence. This allows a breakdown of the event namespace into parts, somewhat like the Domain Name System does on the Internet. Each component identifier may be parametrized by a string or number literal, with a -syntax like a function call. A component may be replaced by a "*" -character, to expand to other matching probe points. These are all -syntactically valid probe points: +syntax like a function call. A component may include a "*" +character, to expand to other matching probe points. A probe point +may be followed by a "?" character, to indicate that it is optional, +and that no error should result if it fails to expand. + +These are all syntactically valid probe points: .SAMPLE kernel.function("foo").return syscall(22) user.inode("/bin/vi").statement(0x2222) end kernel.syscall.* +kernel.function("no_such_function") ? .ESAMPLE Probes may be broadly classified into "synchronous" and @@ -64,6 +68,14 @@ function call, or an interruption from the user. In the case of an error-triggered shutdown, "end" probes are not run. There are no target variables available in either context. +.SS NEVER +The probe point +.IR never +is specially defined by the translator to mean "never". Its probe +handler is never run, though its statements are analyzed for symbol / +type correctness as usual. This probe point may be useful in +conjunction with optional probes. + .SS TIMERS Intervals defined by the standard kernel "jiffies" timer may be used |