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* What's new since version 0.5.13?
- The way in which systemtap resolves function/inline probes has changed:
.function(...) - now refers to all functions, inlined or not
.inline(...) - is deprecated, use instead:
.function(...).inline - filters function() to only inlined instances
.function(...).call - filters function() to only non-inlined instances
.function(...).return - as before, but now pairs best with .function().call
.statement() is unchanged.
* What's new since version 0.5.12?
- When running in -p4 (compile-only) mode, the compiled .ko file name
is printed on standard output.
- An array element with a null value such as zero or an empty string
is now preserved, and will show up in a "foreach" loop or "in" test.
To delete such an element, the scripts needs to use an explicit
"delete array[idx]" statement rather than something like "array[idx]=0".
- The new "-P" option controls whether prologue searching heuristics
will be activated for function probes. This was needed to get correct
debugging information (dwarf location list) data for $target variables.
Modern compilers (gcc 4.1+) tend not to need this heuristic, so it is
no longer default. A new configure flag (--enable-prologues) restores
it as a default setting, and is appropriate for older compilers (gcc 3.*).
- Each systemtap module prints a one-line message to the kernel informational
log when it starts. This line identifies the translator version, base
address of the probe module, a broken-down memory consumption estimate, and
the total number of probes. This is meant as a debugging / auditing aid.
- Begin/end probes are run with interrupts enabled (but with
preemption disabled). This will allow begin/end probes to be
longer, to support generating longer reports.
- The numeric forms of kernel.statement() and kernel.function() probe points
are now interpreted as relocatable values - treated as relative to the
_stext symbol in that kernel binary. Since some modern kernel images
are relocated to a different virtual address at startup, such addresses
may shift up or down when actually inserted into a running kernel.
kernel.statement(0xdeadbeef): validated, interpreted relative to _stext,
may map to 0xceadbeef at run time.
In order to specify unrelocated addresses, use the new ".absolute"
probe point suffix for such numeric addresses. These are only
allowed in guru mode, and provide access to no $target variables.
They don't use debugging information at all, actually.
kernel.statement(0xfeedface).absolute: raw, unvalidated, guru mode only
* What's new since version 0.5.10?
- Offline processing of debugging information, enabling general
cross-compilation of probe scripts to remote hosts, without
requiring identical module/memory layout. This slows down
compilation/translation somewhat.
- Kernel symbol table data is loaded by staprun at startup time
rather than compiled into the module.
- Support the "limit" keyword for foreach iterations:
foreach ([x,y] in ary limit 5) { ... }
This implicitly exits after the fifth iteration. It also enables
more efficient key/value sorting.
- Support the "maxactive" keyword for return probes:
probe kernel.function("sdfsdf").maxactive(848) { ... }
This allows up to 848 concurrently outstanding entries to
the sdfsdf function before one returns. The default maxactive
number is smaller, and can result in missed return probes.
- Support accessing of saved function arguments from within
return probes. These values are saved by a synthesized
function-entry probe.
- Add substantial version/architecture checking in compiled probes to
assert correct installation of debugging information and correct
execution on a compatible kernel.
- Add probe-time checking for sufficient free stack space when probe
handlers are invoked, as a safety improvement.
- Add an optional numeric parameter for begin/end probe specifications,
to order their execution.
probe begin(10) { } /* comes after */ probe begin(-10) {}
- Add an optional array size declaration, which is handy for very small
or very large ones.
global little[5], big[20000]
- Include some example scripts along with the documentation.
- Change the start-time allocation of probe memory to avoid causing OOM
situations, and to abort cleanly if free kernel memory is short.
- Automatically use the kernel DWARF unwinder, if present, for stack
tracebacks.
- Many minor bug fixes, performance, tapset, and error message
improvements.
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