When running perf it finds the kernel symbols and symbols of my program but it does not find external module symbols. I have written a kernel module which I load using insmod how can I tell perf to find its symbols as well?
I am running a 2.6.37.6 kernel (can't upgrade), my perf does not yet support the dwarf option but I think its a symbol issue. I have compiled everything with -g -fno-omit-frame-pointer
I had to make it a kernel module, then perf could find its symbols:
IN_TREE_DIR=/lib/modules/`uname -r`/kernel/modulename
mkdir -p $IN_TREE_DIR
cp modulename.ko $IN_TREE_DIR
depmod -a
Related
I am just doing some simple OCCI thing, however it compiles a bit strangely
Environment:
Oracle VM: Centos7 64bit on Windows 8 64bit
gcc-c++.x86_64
Simply installed Oracle XE by double clicking the rpm (download pages says
linux 64bit)
echo $LD_LIBRARY_PATH yields:
/usr/local/lib64/:/u01/app/oracle/product/11.2.0/xe/lib/
I also tried export LD_LIBRARY_PATH=/u01/app/oracle/product/11.2.0/xe/lib/
so that it yields
/u01/app/oracle/product/11.2.0/xe/lib/
some listing command:
find /u01/app/oracle/product/11.2.0/xe/lib/ -name lib*
yields the following:
/u01/app/oracle/product/11.2.0/xe/lib/
/u01/app/oracle/product/11.2.0/xe/lib/libagtsh.so.1.0
/u01/app/oracle/product/11.2.0/xe/lib/libcell11.so
/u01/app/oracle/product/11.2.0/xe/lib/libclntsh.so.11.1
/u01/app/oracle/product/11.2.0/xe/lib/libnnz11.so
/u01/app/oracle/product/11.2.0/xe/lib/libocci.so.11.1
/u01/app/oracle/product/11.2.0/xe/lib/libclntsh.so
/u01/app/oracle/product/11.2.0/xe/lib/libocci.so
/u01/app/oracle/product/11.2.0/xe/lib/libagtsh.so
and some others....
however the compile command says ld cannot find some libraries:
g++ -o ab -I/u01/app/oracle/product/11.2.0/xe/rdbms/public/ -lnnz11 -lclntsh -locci a.cpp
/usr/bin/ld: cannot find -lnnz11
/usr/bin/ld: cannot find -lclntsh
/usr/bin/ld: cannot find -locci
collect2: error: ld returned 1 exit status
I have tried adding -L/u01/app/oracle/product/11.2.0/xe/lib/, it successfully compiles however running the program will cause it silently crashes / blocks at the simple line
Environment *env = Environment::createEnvironment();
no exceptions caught.
Does anyone know some part I did wrong? or are the two issues related?
And by the way, it USED to work like 5 hours ago, when it suddenly stopped working I reinstalled the whole VM and now it still doesn't work.
however the compile command says ld cannot find some libraries: g++ -o ab -I/u01/app/oracle/product/11.2.0/xe/rdbms/public/ -lnnz11 -lclntsh -locci a.cpp
Your command is incorrect (and the linker is right to complain). You need to tell the linker where to find the library, and you do that with -L flag:
ORACLE=/u01/app/oracle/product/11.2.0/xe
g++ -I ${ORACLE}/rdbms/public -L ${ORACLE}/lib a.cpp -lnnz11 -lclntsh -locci
(Note that your placement of source after library is also incorrect, and I fixed it above. Placement of libraries and sources on link command line matters.)
I have been using clang-3.5 to happily build bitcode versions of musl libc and
use the result to produce nice stand alone executables.
Recent attempts with clang-3.8 have not been so happy. It seems that
the bitcode clang-3.8 generates uses functions defined in
compiler-rt/lib/builtins
Typical examples of functions I find polluting the bitcode are mulxc3, mulsc3, and muldc3. I can solve this by linking against libgcc, or even the llvm alternative if I had any clear idea of what that was. Though I would rather prevent the problem from happening in the first place.
I have seen mention of flags like rtlib=compiler-rt etc, but have found precious little documentation on the subject.
So here are some simple questions.
Is it possible to prevent clang from using the compiler-rt/lib/builtins
in the emitted bitcode? Or if not
Does llvm produce a version of libgcc that I could use. Actually I would
probably build a bitcode version of it, but that is besides the point.
Love to hear some guidance on this.
Added 12/8/2016: So I will illustrate my issues with a particular workflow that
people can reproduce if they wish, or, more likely, just point out where I am being stupid.
So start by checking out:
musllv
and follow the instructions in the README.to compile (here I am using clang-3.8 on ubuntu 14.04)
WLLVM_CONFIGURE_ONLY=1 CC=wllvm ./configure --target=LLVM --build=LLVM
make
cd lib
extract-bc -b libc.a
you will also need the bitcode of a simple executable. I will use nweb.c here.
wllvm nweb.c -o nweb
extract-bc nweb
Now we can do things like:
clang -static -nostdlib nweb.bc libc.a.bc crt1.o libc.a -o nweb
This workflow goes smoothly for clang-3.5 but for clang-3.8 we get:
clang -static -nostdlib nweb.bc libc.a.bc crt1.o libc.a -o nweb
/tmp/libc-f734a3.o: In function `cpowl':
libc.a.bc:(.text+0xbb9a): undefined reference to `__mulxc3'
/tmp/libc-f734a3.o: In function `cpowf':
libc.a.bc:(.text+0x38f7d): undefined reference to `__mulsc3'
/tmp/libc-f734a3.o: In function `csqrt':
libc.a.bc:(.text+0x78fc3): undefined reference to `__muldc3'
/tmp/libc-f734a3.o: In function `cpow':
libc.a.bc:(.text+0xafafc): undefined reference to `__muldc3'
clang-3.8: error: linker command failed with exit code 1 (use -v to seeinvocation)
So as #paul-brannan points out we could try
clang -static -nostdlib --rtlib=compiler-rt nweb.bc libc.a.bc crt1.o libc.a -o nweb
But this is where I am probably being stupid, because I get:
clang-3.8: warning: argument unused during compilation: '--rtlib=compiler-rt'
irregardless of whether I use it as a linking or compiling flag.
OK so I finally managed to make headway on this. I built llvm-3.8.1 together with the compiler-rt project using wllvm and wllvm++.
One of the build products was libclang_rt.builtins-x86_64.a,
and from this archive I was able to extract the bitcode module
libclang_rt.builtins-x86_64.bc
using the command:
extract-bc -b libclang_rt.builtins-x86_64.a
This bitcode module has definitions for those pesky instrinsics like
__mulxc3, __mulsc3, and __muldc3.
Hallelujah!
I have been trying to enable the gold linker on FreeBSD to use the link time optimizations. I made gold from the binutils under /usr/ports. After building binutils using make -k install clean i got ld under /usr/bin and in the directory /usr/local/bin i got ld, ld.gold and ld.bfd.
Now while trying to use link time optimization for the simple example programs here http://llvm.org/docs/GoldPlugin.html (a.c and b.c under the heading 'Examples of Link Time Optimization') i entered the four commands as follows:
clang -flto a.c -c -o a.o
ar q a.a a.o
clang b.c -c -o b.o
clang -flto a.a b.o -o main
I got the following error:
usr/bin/ld: unrecogonized option '-plugin'
usr/bin/ld: use the --help option for usage information
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Is there the problem with the linker that ld.gold is not being called. Should I replace the ld with ld.gold? Does the linker looks in the right directiry for the .so plugins?
The LLVMgold.so and libLTO.so shared objects are in the directory /usr/local/llvm-devel/lib/.
I cannot find the directory where clang is installed. I am not sure where to make the bfd-plugins directory and add the symlinks to LLVMgold.so and libLTO.so.
I am using freebsd 10.1 release. How to enable the gold linker for link time optimizations?
also how can I enable it to be the default linker?
You may want to use ld.gold instead of ld. It is installed at /usr/local/bin/ld.gold. If you are using a Makefile, it would work by setting LD variable to ld.gold, either by modifying your Makefile or specifying it on command line. Example in case you are using lang/clang37:
gmake all CC=clang37 LD=ld.gold
EDIT:
It would be even more neat if you add -fuse-ld=gold to your LDFLAGS:
LDFLAGS=-fuse-ld=gold
I'm not sure ld.bfd allows plugins, but I could be wrong.
Your /usr/bin/ld should be a symlink to whatever linker you want. You can change which linker is used by using binutils-config. Check the man-page here: http://www.linuxhowtos.org/manpages/8/binutils-config.htm. I realise this is a Linux link, but it's directed at binutils itself rather than linux-specifically.
It should be something along the lines binutils-config --gold.
On my Gentoo box it is binutils --linker=gold
EDIT: As pointed out, binutils-config doesn't work on BSD it seems. You can still manually update the symlinks though, the downside is that there might be a few of them.
You can find out which ld is used by your compiler by using gcc -print-prog-name=ld or clang -print-prog-name=ld. The file printed should be a symlink you can re-create to point to ld.gold as oposed to ld.bfd.
Is there a way to instruct C++ Builder's linker to output DWARF debug information (64-bit C++ apps) in standalone file rather than inject it directly into executable? I.e. the option similar to "Place debug information in separate TDS file" (which does not work for DWARF debug format).
If there is no such option - is there a way to strip info from already compiled executable?
To place debug info in separate file follow below steps
// Build
$ clang -O2 -g -o hello.full hello.c
// Package hello.stripped is run as "hello" in production environment
$ strip -o hello.stripped hello.full
// Extract debug info to separate file
$ objcopy --only-keep-debug hello.full hello.debug
// Create a section which contains a reference to debug file
$ objcopy --strip-debug --add-gnu-debuglink=hello.debug hello.full hello
// Debug - GDB automatically reads hello.debug
$ gdb hello
. . .
Reading symbols from ./hello...
Reading symbols from /homes/syrajendra/hello.debug...done.
(gdb)
// Core from hello.stripped
$ gdb --core core-file --exec hello
Assuming you are on a platform with GNU Binutils you can use objcopy to extract the DWARF information to a separate file as a post-compilation step. If you like you can then use strip to remove the debugging information from the executable binary.
I'm trying real hard to install vowpal wobbit and it fails when i run the make file, throwing:
cd library; make; cd ..
g++ -g -o ezexample temp2.cc -L ../vowpalwabbit -l vw -l allreduce -l boost_program_options -l z -l pthread
ld: library not found for -lboost_program_options collect2: ld returned 1 exit status make[1]: *** [ezexample] Error 1'
I then added the links to the boost library here by specifying -L/usr/local/lib
Now I get the following error:
g++ -g -o ezexample temp2.cc -L/usr/local/lib ../vowpalwabbit -l vw -l allreduce -l boost_program_options -l z -l pthread
ld: library not found for -lvw
collect2: ld returned 1 exit status
make: *** [ezexample] Error 1
I happened to get everything working on OS X 10.7 as follows:
Make sure you have a working Boost installation. As indicated on the Getting started page, usually we only need header files, but some Boost libraries must be built separately, including the program_options library which is used to process options from command line or config file. Go into your boost folder, and then at your shell prompt:
$ ./bootstrap.sh
$ ./bjam
This will compile and build everything. You should now have a bin.v2/ directory in your boost directory, with all built libraries for your system (static and threaded libs).
$ ls bin.v2/libs/
date_time iostreams python serialization test
filesystem math random signals thread
graph program_options regex system wave
More importantly, extra Boost libraries are made available in the stage/lib/ directory. For me, these are Mach-O 64-bit dynamically linked shared library x86_64.
The include path should be your_install_dir/boost_x_xx_x, where boost_x_xx_x is the basename of your working Boost. (I personally have boost_1_46_1 in /usr/local/share/ and I symlinked it to /usr/local/share/boost to avoid having to remember version number.) The library path (for linking) should read your_install_dir/boost_x_xx_x/stage/lib. However, it might be best to symlink or copy (which is what I did) everything in usual place, i.e. /usr/local/include/boost for header files, and /usr/local/lib for libraries.
Edit the Makefile from the vowpal_wabbit directory, and change the include/library paths to reflect your current installation. The Makefile should look like this (first 12 lines):
COMPILER = g++
UNAME := $(shell uname)
ifeq ($(UNAME), FreeBSD)
LIBS = -l boost_program_options -l pthread -l z -l compat
BOOST_INCLUDE = /usr/local/include
BOOST_LIBRARY = /usr/local/lib
else
LIBS = -l boost_program_options -l pthread -l z
BOOST_INCLUDE = /usr/local/share/boost # change path to reflect yours
BOOST_LIBRARY = /usr/local/share/boost/stage/lib # idem
endif
Then, you are ready to compile vowpal_wabbit (make clean in case you already compiled it):
$ make
$ ./vw --version
6.1
$ make test
You can also install vowpal wabbit on OS X using brew:
brew install vowpal-wabbit
Or you can just install boost, and then install vw from the github repo.
brew install boost
For installation on CentOS 7 (6.5 perl version is too old for latest vw source code), I've found the instructions at http://wkoplitz.blogspot.be/2012/12/vowpal-wabbit-on-centos.html to work fine:
yum install zlib-devel boost-devel
yum groupinstall "Development Tools"
git clone git://github.com/JohnLangford/vowpal_wabbit.git
cd vowpal_wabbit
./autogen.sh
make
make test
Good news:
As of the latest release VowpalWabbit version 9.1.0, vw no longer relies on Boost program_options
From the release highlights:
Removal of Boost Program Options dependency
For a long time we have depended on Boost Program Options
for command line options parsing. In this release, we have > replaced this dependency with our own implementation of
command line parsing. Apart from one place where we depend > on Boost Math in standalone mode, this means that VW core
and the command line tool are free of Boost dependencies
hopefully making the code a bit easier to build and package.
Vowpal Wabbit 9.1.0 release notes