Thursday, March 31, 2011

Trying DTrace for Linux on Fedora 14

Some months, or even years ago, I noticed that Paul Fox, the author of the CRiSP editor, was working on a port of DTrace to Linux. Paul seems to have started work on this port back at the start of 2008. He has made regular progress reports on his website blog, and from June 2010, he also started using Google's blogger, which did seem to have taken over as Paul's main blog, but now I notice he has put all the blogger posts back on his website blog!

In February 2011, I finally go around to trying out the code.

Paul seems to be developing on/for Ubuntu, but I wanted to try it on Fedora 14. I had a number of problems, first indentifying which RPM packages I needed to install for the build. And then there were various compile problems, and it took me a while to figure out how to resolve these problems, as I would not claim to be any sort of expert on this.

Here is a list of the RPM packages I needed to install to get the code to compile:


I was eventually able to work out the necessary patches to get it to compile on Fedora 14. I did try emailing Paul to give him some feedback, and I think he may have read my emails, but so far I have never received a reply back from him!

Here for posterity, I publish my patch, just to prove I did some work! But note that this is already out of date, as Paul's DTrace for Linux port has continued to moved on.
$ diff -uNr dtrace-20110215 dtrace-20110215.fed14/
diff -uNr dtrace-20110215/cmd/ctfconvert/dwarf.c dtrace-20110215.fed14/cmd/ctfconvert/dwarf.c
--- dtrace-20110215/cmd/ctfconvert/dwarf.c 2010-08-24 23:34:26.000000000 +0100
+++ dtrace-20110215.fed14/cmd/ctfconvert/dwarf.c 2011-03-18 01:19:57.786335906 +0000
@@ -88,9 +88,9 @@
#include <errno.h>
#include "linux.h"
#include <libelf.h>
-#include <libdwarf.h>
+#include <libdwarf/libdwarf.h>
#include <libgen.h>
-#include <dwarf.h>
+#include <libdwarf/dwarf.h>

#include "ctf_headers.h"
#include "ctftools.h"
diff -uNr dtrace-20110215/cmd/ctfconvert/makefile dtrace-20110215.fed14/cmd/ctfconvert/makefile
--- dtrace-20110215/cmd/ctfconvert/makefile 2010-10-17 17:55:26.000000000 +0100
+++ dtrace-20110215.fed14/cmd/ctfconvert/makefile 2011-03-18 01:19:23.255448742 +0000
@@ -44,7 +44,7 @@
LIBS = ../../build/libctf.a -ldwarf -lbfd -lelf -lz

- @if [ ! -f /usr/lib/libdwarf.a ]; then \
+ @if [ ! -f /usr/lib64/libdwarf.a ]; then \
echo "=================================================================" ; \
echo "=== You need /usr/lib/libdwarf.a and /usr/lib/libbfd.a installed to build." ; \
echo "=== " ; \
diff -uNr dtrace-20110215/tools/ dtrace-20110215.fed14/tools/
--- dtrace-20110215/tools/ 2011-01-26 23:36:06.000000000 +0000
+++ dtrace-20110215.fed14/tools/ 2011-03-19 14:16:48.725192127 +0000
@@ -59,7 +59,7 @@

if (! -f "/usr/include/gelf.h") {
- print "Error: you dont appear to have /usr/include/elf.h, which means\n";
+ print "Error: you dont appear to have /usr/include/gelf.h, which means\n";
print "compilation will fail. You should add the libelf-dev package to\n";
print "your system and retry the 'make all'.\n";
diff -uNr dtrace-20110215/tools/ dtrace-20110215.fed14/tools/
--- dtrace-20110215/tools/ 2010-08-26 10:03:21.000000000 +0100
+++ dtrace-20110215.fed14/tools/ 2011-03-18 01:21:59.600884493 +0000
@@ -19,11 +19,11 @@
cd $build_dir
cmd=`grep '^cmd_' $pwd/build/driver/.cpu_x86.o.cmd |
sed -e 's/^.* := //' |
-sed -e 's/-Wp,-MD[^ ]* /-g /' |
+sed -e 's/-Wp,-MD[^ ]* /-gdwarf-2 /' |
sed -e 's/\\\\//g' |
sed -e 's/cpu_x86/ctf_struct/g' `
#echo $cmd
eval $cmd
cd $pwd
-build/ctfconvert -L label -o build/linux-$BUILD_KERNEL.ctf build/driver/.tmp_ctf_struct.o
+build/ctfconvert -L label -o build/linux-$BUILD_KERNEL.ctf build/driver/ctf_struct.o
ls -l build/linux-$BUILD_KERNEL.ctf

And here is a very quick and basic test, to show DTrace running:

# uname -a:
Linux fed14-64 #1 SMP Mon Feb 7 07:06:44 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux
# make load
01:26:50 Syncing...
01:26:50 Loading: build/driver/dtracedrv.ko
01:26:52 Preparing symbols...
01:26:52 Probes available: 314700
01:26:56 Time: 6s

# dtrace -n BEGIN
dtrace: description 'BEGIN' matched 1 probe
1 1 :BEGIN

Admittedly, that is the most basic DTrace one-liner you can possibly try. But I did also try a few 'syscall' one-liners, mostly with success.

Anyway, once I got this going, I wanted to try with Paul's latest release of the code, to get his latest bug fixes, but I was stopped in my tracks, as his FTP site was down. And it continued to be down, for over a week, which was quite frustrating. I tried emailing him, and leaving a blog comment, but again, I got no response. And there was no mention of this problem on his web sites, or blog.

Eventualy, while Googling, I discovered that Paul has a Twitter account, and that he had announced there, that he has a new host name for his FTP site. There is no mention of Paul's Twitter account on his web sites or blogs, at this moment. So I will publicize it here, as he does seem to make good use of it to report progress with DTrace for Linux:!/crispeditor

And for anyone wanting to try compiling the DTrace for Linux code, please note the new download site is:

Ok, so now I guess I had better download the latest release of the code, and try it out.

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