DTrace TODO

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This page is for brainstorming and coordinating efforts with DTrace development. Anyone who has and idea/wish can add an item and if you work on one of those you grab it. You can always mail the freebsd-dtrace mailing list in case you do not have write access to the wiki, have questions or want to work on this but are not (yet;-) a FreeBSD committer.

Most of these problems are specific to FreeBSD's DTrace implementation, but some of them are upstream (illumos) issues as well.

added by	responsible	state	task
JohnBirrell		committed	We need a BSD version of libelf. Or at least one that can handle host endian != target endian. This affects cross-builds on dissimilar architectures (like i386 host, sparc64 target). See LibElf
JohnBirrell	StaceySon	committed	Get ustack()/jstack() actions working. See ustack patch. (Only outputs hex PC values for now because of the lack of symbol table support in libproc.)
JohnBirrell	MarkJohnston (partially)	committed	Implement args beyond arg4. See r256822 and r251238.
JohnBirrell	StaceySon	committed	Implement lockstat – including both driver and command. See lockstat kernel patch, lockstat cmd patch, and ksyms pseudo driver.
JohnBirrell			Implement toxic ranges.
JohnBirrell			Implement stop() action.
JohnBirrell			Port MDB DTrace-related dcmds to FreeBSD debugger.
JohnBirrell	StaceySon	committed	Get stack() action working. (Committed a while ago.)
JohnBirrell			Need to add mailbox IPI's to allow a function to be executed on another CPU.
JohnBirrell			Credentials and privileges need a lot of work.
JohnBirrell			The ability to trace a process running on a different CPU is an important part of DTrace. Somebody needs to test that.
JohnBirrell	MikeMa, MarkJohnston	committed	Solaris has a vmem subsystem which is an integral part of their virtual memory. FreeBSD 10 has a new vmem(9) implementation with the required functions vmem_create(), vmem_destroy(), vmem_alloc(), and vmem_free().
JohnBirrell			There are lots of places in the build where the ctfconvert and ctfmerge tools complain about the objects they are processing. Those issues need to be resolved.
StaceySon	RuiPaulo	committed	Add symbol support to libproc.
StaceySon			Add missing built-in variables: ipl, zonename (jailname)
StaceySon	StaceySon	committed	Add missing built-in variable 'uregs[]'. See uregs patch.
StaceySon	StaceySon	committed	Add missing built-in variable 'ustackdepth'. See ustackdepth patch
StaceySon	StaceySon	committed	Add missing built-in variable 'ucaller'. See ucaller patch
StaceySon		committed	Get uaddr(), ufunc(), umod(), and usym() action funtions working.
StaceySon	StaceySon	committed	Fix prochandler() in dtrace.c so that 'dtrace -c' works correctly. See prochandler preliminary patch
StaceySon	RyanStone, MarkJohnston	committed	SDT provider support for kernel modules. Reported by np@.
StaceySon	AndriyGapon	committed	DTrace is missing symbol info for kernel modules. Reported by np@.
PedroGiffuni			The DTrace userland tool has to run as root: it would be beneficial to have it use capsicum(4).
MarkJohnston			Fix problems with lockstat. It basically works, but there are problems. See avg's post. Also go through all the examples in the illumos lockstat(1) man page and fix them for FreeBSD; many of them are omitted from the FreeBSD lockstat(1) man page because they don't work properly. Also see PR 166925.
MarkJohnston	MarkJohnston	wip	Get libproc to look up symbols through a .gnu_debuglink ELF section, so that userland DTrace works properly with WITH_DEBUG_FILES.
MarkJohnston			dtrace(1) apparently has various troubles when run within in a jail.
MarkJohnston	MarkJohnston	wip	Get the DTrace test suite down to 0 failures. On my machine it's currently at 948/999 tests passing. Many of the failing tests are for userland DTrace. I've also fixed some test issues caused by various Solarisms. Also find a good place to add regression tests for issues found in FreeBSD.
MarkJohnston	MarkJohnston	wip	Port the cpc provider to FreeBSD, or implement something similar.
MarkJohnston			There are a bunch of ports that have USDT probes that aren't enabled on FreeBSD. Find them and add support. An easy place to start is tcl, a less easy place to start is perl, and a less less easy place to start is openJDK. Email markj@freebsd.org for the first two, I've made some progress on them already.
MarkJohnston			Submit DTrace patches back to illumos. There are some bug fixes in our DTrace implementation that are not specific to FreeBSD. They are minor for the most part, but should be upstreamed. Maybe the illumos people don't mind having #ifdef FreeBSD in their code? :)
MarkJohnston			Improve documentation. I would very much like to see man pages for each of our SDT providers. Here is a proposed example.
MarkJohnston			plockstat provider
MarkJohnston			Fix dtrace kernel module unloads. At the moment this frequently causes kernel crashes, making it difficult to test changes to the DTrace kernel code.
MarkJohnston			Fix dtrace -h and dtrace -G to not depend on dtrace.ko being loaded (I'm pretty sure there's no reason for this). Otherwise ports with DTrace probes can't be built as non-root or without loading the modules first.
HowardSu	HowardSu	wip	Port dtrace to arm platform. based on the early work done by gonzo@