gonzo at freebsd.org
Thu Mar 1 22:05:46 UTC 2012
Last few weeks I've been working on DTrace port for MIPS architecture.
I believe that project reached the stage when it's ready for public
review/testing before going into the tree.
Patch and some information could be found here:
I'd appreciate review/testing from interested parties and if there are
no major roadblocks the plan is to commit this patch sometime next
DTrace/MIPS passes substantial part of DTrace suite on my
==== TEST RESULTS ====
There are some caveats/limitations though:
- fbt, pid, lockstat, profile providers are not implemented
- MIPS passes function arguments in registers and unless they're
saved on stack the value of some might be unavailable in
backtrace. So values of argN variables might be bogus sometimes.
- dtrace uses kldstat(2) to get path to kernel binary and for
"embedded" systems (e.g. without loader(8)) it's just "kernel"
So kernel binary should be in current directory so dtrace could
get CTF data from it. We need either command-line switch or env
variable to let dtrace know where to look for binary. I haven't
yet decided which way to go.
- Not really dtrace issue, but somewhat related. FreeBSD/MIPS default
kernel stacks size seems to be insufficient to load kernel
modules with dependency chain longer then three modules
(dtrace_test -> dtrace_all -> dtrace -> cyclic -> opensolaris)
Sometimes I get kernel stack exhaustion as a combination of
FS-related calls that goes down to NFS functions + WITNESS code.
No proper solution for it yet. Workaround - load module one by
- Tested only on mips64be platform. mips32be, mips32le, mips64le
were not tested.
dtrace-all.diff - is a cumulative patch that contains diff between
HEAD branch and project branch in p4. In order to make code review
easier I split it into several sub-patches based on functionality area.
Current version of ctfmerge assumes that target byte order is the
same as host one. This patch checks byte order of ELF files being
used to decide whether byte order in CTF structures' fields
should be reversed.
- Disable SGI compatibility for generated DWARF data.
It confuses ctfconvert.
- Set as(1) default ABI and target size the same as target platform
- Kernel part of DTrace code
- More intelligent kernel stack overflow handler
- Userland part of DTrace code
- Build DTrace tols as a part of toolchain build if
- Various libraries' plugs for MIPS
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