* New to musl and C++ compiling @ 2019-01-21 10:24 Michele Portolan 2019-01-21 11:53 ` Szabolcs Nagy 0 siblings, 1 reply; 5+ messages in thread From: Michele Portolan @ 2019-01-21 10:24 UTC (permalink / raw) To: musl Hello, I just installed MUSL because I have a C++ multithreaded application that uses threads heavily and I would like to make it independent from an OS. I was able to easily install and run MUSL for C targets, but when I try a simple C++ Hello world I get an error for the standard libs. My file is the simplest possible (no multithreading to start with): #include <iostream> int main() { std::cout << "Hello, World" << std::endl; return 0; } Here is my output for standard and musl-based compilation. portolan@noumea:~/musl/examples$ g++ -o test_cpp test_cpp.cpp portolan@noumea:~/musl/examples$ ./test_cpp Hello, World portolan@noumea:~/musl/examples$ g++ -o test_cpp test_cpp.cpp -specs "/home/portolan/musl/install/lib/musl-gcc.specs" test_cpp.cpp:1:11: fatal error: iostream: No such file or directory #include <iostream> ^~~~~~~~~~ compilation terminated. I am probably missing something REALLY basic, at least I hope so! Best regards, Michele ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: New to musl and C++ compiling 2019-01-21 10:24 New to musl and C++ compiling Michele Portolan @ 2019-01-21 11:53 ` Szabolcs Nagy 2019-01-21 12:02 ` Szabolcs Nagy 0 siblings, 1 reply; 5+ messages in thread From: Szabolcs Nagy @ 2019-01-21 11:53 UTC (permalink / raw) To: musl; +Cc: Michele Portolan * Michele Portolan <michele.portolan@grenoble-inp.fr> [2019-01-21 11:24:12 +0100]: > Hello, > > I just installed MUSL because I have a C++ multithreaded application that > uses threads heavily and I would like to make it independent from an OS. I > was able to easily install and run MUSL for C targets, but when I try a > simple C++ Hello world I get an error for the standard libs. > > My file is the simplest possible (no multithreading to start with): > > #include <iostream> > > int main() { > std::cout << "Hello, World" << std::endl; > return 0; > } > > Here is my output for standard and musl-based compilation. > > portolan@noumea:~/musl/examples$ g++ -o test_cpp test_cpp.cpp > portolan@noumea:~/musl/examples$ ./test_cpp > Hello, World > portolan@noumea:~/musl/examples$ g++ -o test_cpp test_cpp.cpp -specs > "/home/portolan/musl/install/lib/musl-gcc.specs" for c++ the recommended practice is to use a cross compiler that is built for musl, instead of a glibc based native compiler with a specs file or other wrapping mechanism, because c++ headers are difficult to get right: in this case the specs file disabled all c++ header paths, you need to add those back manually, see g++ -v -E -xc++ - </dev/null but there may be still issues - the header ordering matters as libstdc++ uses include_next and - some headers are installed based on the libc found at configure time of gcc, so the abi is slightly different depending on what libc you built your compiler for, - e.g. with static linking (which you need if you want a portable executable) one issue is that libstdc++ has a broken way to detect multi-threadedness and all locks become nops (unless your binary has a definition for the 'pthread_cancel' symbol). if gcc is configured for *-musl* this is fixed. in short: use a cross compiler targetting *-linux-musl, there are prebuilt ones at http://musl.cc/ (note that you will have to build and install all your application dependencies into a path where the cross compiler can find them) > test_cpp.cpp:1:11: fatal error: iostream: No such file or directory > #include <iostream> > ^~~~~~~~~~ > compilation terminated. > > I am probably missing something REALLY basic, at least I hope so! > > Best regards, > > > Michele ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: New to musl and C++ compiling 2019-01-21 11:53 ` Szabolcs Nagy @ 2019-01-21 12:02 ` Szabolcs Nagy 2019-01-21 13:13 ` Michele Portolan 0 siblings, 1 reply; 5+ messages in thread From: Szabolcs Nagy @ 2019-01-21 12:02 UTC (permalink / raw) To: musl, Michele Portolan * Szabolcs Nagy <nsz@port70.net> [2019-01-21 12:53:13 +0100]: > * Michele Portolan <michele.portolan@grenoble-inp.fr> [2019-01-21 11:24:12 +0100]: > > Hello, > > > > I just installed MUSL because I have a C++ multithreaded application that > > uses threads heavily and I would like to make it independent from an OS. I > > was able to easily install and run MUSL for C targets, but when I try a > > simple C++ Hello world I get an error for the standard libs. > > > > My file is the simplest possible (no multithreading to start with): > > > > #include <iostream> > > > > int main() { > > std::cout << "Hello, World" << std::endl; > > return 0; > > } > > > > Here is my output for standard and musl-based compilation. > > > > portolan@noumea:~/musl/examples$ g++ -o test_cpp test_cpp.cpp > > portolan@noumea:~/musl/examples$ ./test_cpp > > Hello, World > > portolan@noumea:~/musl/examples$ g++ -o test_cpp test_cpp.cpp -specs > > "/home/portolan/musl/install/lib/musl-gcc.specs" > > for c++ the recommended practice is to use a cross compiler that > is built for musl, instead of a glibc based native compiler with > a specs file or other wrapping mechanism, because c++ headers are > difficult to get right: in this case the specs file disabled all > c++ header paths, you need to add those back manually, see > > g++ -v -E -xc++ - </dev/null > > but there may be still issues > - the header ordering matters as libstdc++ uses include_next and > - some headers are installed based on the libc found at configure > time of gcc, so the abi is slightly different depending on what > libc you built your compiler for, > - e.g. with static linking (which you need if you want a portable > executable) one issue is that libstdc++ has a broken way to > detect multi-threadedness and all locks become nops (unless your > binary has a definition for the 'pthread_cancel' symbol). > if gcc is configured for *-musl* this is fixed. > > in short: use a cross compiler targetting *-linux-musl, there are > prebuilt ones at http://musl.cc/ > (note that you will have to build and install all your application > dependencies into a path where the cross compiler can find them) oh and if you have many dependencies then the simplest way is of course to use a musl based distro (alpine, void, adelie,..) then you can use all the prebuilt packages and the native toolchain with g++ -static and you get a portable executable. (setting up a chroot or docker with whatever distro should not be too much work). > > test_cpp.cpp:1:11: fatal error: iostream: No such file or directory > > #include <iostream> > > ^~~~~~~~~~ > > compilation terminated. > > > > I am probably missing something REALLY basic, at least I hope so! > > > > Best regards, > > > > > > Michele ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: New to musl and C++ compiling 2019-01-21 12:02 ` Szabolcs Nagy @ 2019-01-21 13:13 ` Michele Portolan 2019-01-21 13:55 ` Szabolcs Nagy 0 siblings, 1 reply; 5+ messages in thread From: Michele Portolan @ 2019-01-21 13:13 UTC (permalink / raw) To: musl Thanks for the information. You say "use a cross compiler that is built for musl" ... how do I do this? Binaries are useful, but if I can also get the build process right it is more powerful, and easier to pass to students (I am an academic). Thanks, Michele On 21/01/2019 13:02, Szabolcs Nagy wrote: > * Szabolcs Nagy <nsz@port70.net> [2019-01-21 12:53:13 +0100]: > >> * Michele Portolan <michele.portolan@grenoble-inp.fr> [2019-01-21 11:24:12 +0100]: >>> Hello, >>> >>> I just installed MUSL because I have a C++ multithreaded application that >>> uses threads heavily and I would like to make it independent from an OS. I >>> was able to easily install and run MUSL for C targets, but when I try a >>> simple C++ Hello world I get an error for the standard libs. >>> >>> My file is the simplest possible (no multithreading to start with): >>> >>> #include <iostream> >>> >>> int main() { >>> std::cout << "Hello, World" << std::endl; >>> return 0; >>> } >>> >>> Here is my output for standard and musl-based compilation. >>> >>> portolan@noumea:~/musl/examples$ g++ -o test_cpp test_cpp.cpp >>> portolan@noumea:~/musl/examples$ ./test_cpp >>> Hello, World >>> portolan@noumea:~/musl/examples$ g++ -o test_cpp test_cpp.cpp -specs >>> "/home/portolan/musl/install/lib/musl-gcc.specs" >> for c++ the recommended practice is to use a cross compiler that >> is built for musl, instead of a glibc based native compiler with >> a specs file or other wrapping mechanism, because c++ headers are >> difficult to get right: in this case the specs file disabled all >> c++ header paths, you need to add those back manually, see >> >> g++ -v -E -xc++ - </dev/null >> >> but there may be still issues >> - the header ordering matters as libstdc++ uses include_next and >> - some headers are installed based on the libc found at configure >> time of gcc, so the abi is slightly different depending on what >> libc you built your compiler for, >> - e.g. with static linking (which you need if you want a portable >> executable) one issue is that libstdc++ has a broken way to >> detect multi-threadedness and all locks become nops (unless your >> binary has a definition for the 'pthread_cancel' symbol). >> if gcc is configured for *-musl* this is fixed. >> >> in short: use a cross compiler targetting *-linux-musl, there are >> prebuilt ones at http://musl.cc/ >> (note that you will have to build and install all your application >> dependencies into a path where the cross compiler can find them) > oh and if you have many dependencies then the simplest way is of > course to use a musl based distro (alpine, void, adelie,..) then > you can use all the prebuilt packages and the native toolchain > with g++ -static and you get a portable executable. > (setting up a chroot or docker with whatever distro should not be > too much work). > >>> test_cpp.cpp:1:11: fatal error: iostream: No such file or directory >>> #include <iostream> >>> ^~~~~~~~~~ >>> compilation terminated. >>> >>> I am probably missing something REALLY basic, at least I hope so! >>> >>> Best regards, >>> >>> >>> Michele ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: New to musl and C++ compiling 2019-01-21 13:13 ` Michele Portolan @ 2019-01-21 13:55 ` Szabolcs Nagy 0 siblings, 0 replies; 5+ messages in thread From: Szabolcs Nagy @ 2019-01-21 13:55 UTC (permalink / raw) To: musl * Michele Portolan <michele.portolan@grenoble-inp.fr> [2019-01-21 14:13:07 +0100]: > Thanks for the information. > > You say "use a cross compiler that is built for musl" ... how do I do this? build gcc for x86_64-linux-musl target, there are some subtleties, so it may be easier to use an existing build script such as https://github.com/richfelker/musl-cross-make and then make -j$(nproc) TARGET=x86_64-linux-musl install and then use "output/bin/x86_64-linux-musl-g++ -static" > > Binaries are useful, but if I can also get the build process right it is > more powerful, and easier to pass to students (I am an academic). > > Thanks, > > > Michele > > On 21/01/2019 13:02, Szabolcs Nagy wrote: > > * Szabolcs Nagy <nsz@port70.net> [2019-01-21 12:53:13 +0100]: > > > > > * Michele Portolan <michele.portolan@grenoble-inp.fr> [2019-01-21 11:24:12 +0100]: > > > > Hello, > > > > > > > > I just installed MUSL because I have a C++ multithreaded application that > > > > uses threads heavily and I would like to make it independent from an OS. I > > > > was able to easily install and run MUSL for C targets, but when I try a > > > > simple C++ Hello world I get an error for the standard libs. > > > > > > > > My file is the simplest possible (no multithreading to start with): > > > > > > > > #include <iostream> > > > > > > > > int main() { > > > > std::cout << "Hello, World" << std::endl; > > > > return 0; > > > > } > > > > > > > > Here is my output for standard and musl-based compilation. > > > > > > > > portolan@noumea:~/musl/examples$ g++ -o test_cpp test_cpp.cpp > > > > portolan@noumea:~/musl/examples$ ./test_cpp > > > > Hello, World > > > > portolan@noumea:~/musl/examples$ g++ -o test_cpp test_cpp.cpp -specs > > > > "/home/portolan/musl/install/lib/musl-gcc.specs" > > > for c++ the recommended practice is to use a cross compiler that > > > is built for musl, instead of a glibc based native compiler with > > > a specs file or other wrapping mechanism, because c++ headers are > > > difficult to get right: in this case the specs file disabled all > > > c++ header paths, you need to add those back manually, see > > > > > > g++ -v -E -xc++ - </dev/null > > > > > > but there may be still issues > > > - the header ordering matters as libstdc++ uses include_next and > > > - some headers are installed based on the libc found at configure > > > time of gcc, so the abi is slightly different depending on what > > > libc you built your compiler for, > > > - e.g. with static linking (which you need if you want a portable > > > executable) one issue is that libstdc++ has a broken way to > > > detect multi-threadedness and all locks become nops (unless your > > > binary has a definition for the 'pthread_cancel' symbol). > > > if gcc is configured for *-musl* this is fixed. > > > > > > in short: use a cross compiler targetting *-linux-musl, there are > > > prebuilt ones at http://musl.cc/ > > > (note that you will have to build and install all your application > > > dependencies into a path where the cross compiler can find them) > > oh and if you have many dependencies then the simplest way is of > > course to use a musl based distro (alpine, void, adelie,..) then > > you can use all the prebuilt packages and the native toolchain > > with g++ -static and you get a portable executable. > > (setting up a chroot or docker with whatever distro should not be > > too much work). > > > > > > test_cpp.cpp:1:11: fatal error: iostream: No such file or directory > > > > #include <iostream> > > > > ^~~~~~~~~~ > > > > compilation terminated. > > > > > > > > I am probably missing something REALLY basic, at least I hope so! > > > > > > > > Best regards, > > > > > > > > > > > > Michele ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2019-01-21 13:55 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2019-01-21 10:24 New to musl and C++ compiling Michele Portolan 2019-01-21 11:53 ` Szabolcs Nagy 2019-01-21 12:02 ` Szabolcs Nagy 2019-01-21 13:13 ` Michele Portolan 2019-01-21 13:55 ` Szabolcs Nagy
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