I have been attempting to link a MACHO formatted object file on Linux, but I have failed miserably. So far, I have created the object file by running:
nasm -fmacho -o machoh.o hello.o
I have tried linking using:
clang --target=x86_64-apple-darwin machoh.o
but that failed. I have attempted using GCC, LD, and other linkers but I have still failed miserably. Are there any ideas on how I could solve my problem?
Thank you very much.
The most accessible solution would be lld, the LLVM linker.
lld does not ship with clang, but is a separate package.
sudo apt install lld
If you installed a version of clang that isn't the default (e.g. clang-12 explicitly), then you should use the same version for lld (i.e. lld-12).
Get a MacOS SDK from somewhere. This GitHub repo archives them.
If you're uncomfortable using the above, the "legitimate" way of obtaining it without a Mac would be:
Create an Apple ID
Go to https://developer.apple.com/download/all/
Download the "Command Line Tools for Xcode <version>"
Mount or extract the dmg
Extract the XAR package
For each ".pkg" folder inside, run pbzx <Payload | cpio -i
Find the Library/Developer/CommandLineTools/SDKs/MacOSX.sdk inside.
Feed both of the above to clang:
clang --target=x86_64-apple-darwin -fuse-ld=lld --sysroot=path/to/MacOSX.sdk machoh.o
I have tried linking using: clang --target=x86_64-apple-darwin machoh.o
but that failed.
Failed how? Details matter.
Anyway, there are 3 commonly used linkers on Linux: BFD-ld, Gold, and (newest) LLD.
Of these, Gold is an ELF-only linker, and will not work for Mach-O.
BFD-ld is only configured to support a few emulations (use ld --help to see which ones) in my distribution. BFD does appear to support Mach-O, so it's probably possible to build a Linux BFD-ld cross-linker with such support.
LLD should support Mach-O out of the box, but you are probably not using LLD.
So your first step should be to figure out which linker clang --target=x86_64-apple-darwin ... uses, and then make it use the one which does support Mach-O.
Related
If you have an answer for this, or further information, I'd welcome it. I'm following advice from here, to offer some unsolicited help by posting this question then an answer I've already found for it.
I have a bare-metal ARM board for which I'm building a cross-toolchain, from sources for GNU binutils, gcc and gdb, and for SourceWare's Newlib. I got those four working and cross-built a DoNothing.c into an ELF file - but I couldn't disassemble it with this:
$ arm-none-eabi-objdump -S DoNothing.elf
The error was:
$ arm-none-eabi-objdump: error while loading shared libraries: libdebuginfod.so.1: cannot open shared object file: No such file or directory
I'll follow up with a solution.
The error was correct - my system didn't have libdebuginfod.so.1 installed - but I have another cross-binutils, installed from binary for a different target, and its objdump -S works fine on the same host. Why would one build of objdump complain about missing that shared library, when clearly not all builds of objdump need it?
First I tried rebuilding cross binutils, specifying --without-debuginfod as a configure option. No change, which seems odd: surely that should build tools that not only don't use debuginfod but which don't depend on it in any way. (If someone can answer that, or point out what I've misunderstood, it may help people.)
Next I figured debuginfod was inescapable (for my cross-tools built from source at least), so I'd install it to get rid of the error. It's a component of the elfutils package, but installing the latest elfutils available for my Ubuntu 20.04 system didn't bring libdebuginfod.so.1 with it.
I found a later one, for Arch Linux, whose package contents suggested it would - but its package format doesn't match Ubuntu's and installing it was going to involve a lot of work. Instead I opted to build it from the Arch Linux source package. However, running ./configure on that gave a couple of infuriatingly similar errors:
configure: checking libdebuginfod dependencies, --disable-libdebuginfod or --enable-libdebuginfo=dummy to skip
...
configure: error: dependencies not found, use --disable-libdebuginfod to disable or --enable-libdebuginfod=dummy to build a (bootstrap) dummy library.
No combination of those suggestions would allow configure for elfutils-0.182 to run to completion.
The problem of course was my own lack of understanding. The solution came from the Linux From Scratch project: what worked was to issue configure with both of the suggested options, like this:
$ ./configure --prefix=/usr \
--disable-debuginfod \
--enable-libdebuginfod=dummy \
--libdir=/lib
That gave a clean configure; make worked first time, as did make check and then sudo make install which of course installed libdebuginfod.so.1 as required. I then had an arm-none-eabi-objdump which disassembles cross-compiled ELF files without complaining.
I am trying to cross-compile my Rust project on Mac OS to Linux using cargo build --target=x86_64-unknown-linux-musl.
I installed the binary for Linux + musl cross-compilation on mac using brew install FiloSottile/musl-cross/musl-cross as I would ideally want a standalone binary.
I also installed the target using rustup target add x86_64-unknown-linux-gnu
And I have the following in my .cargo/config:
[target.x86_64-unknown-linux-musl]
linker = "x86_64-linux-musl-gcc"
However, I ran into issues with 2 libraries - sqlite3 and pcap:
= note: /usr/local/Cellar/musl-cross/0.9.8/libexec/bin/../lib/gcc/x86_64-linux-musl/6.4.0/../../../../x86_64-linux-musl/bin/ld: cannot find -lsqlite3
/usr/local/Cellar/musl-cross/0.9.8/libexec/bin/../lib/gcc/x86_64-linux-musl/6.4.0/../../../../x86_64-linux-musl/bin/ld: cannot find -lpcap
collect2: error: ld returned 1 exit status
I was able to solve the sqlite3 linker issue by adding features = ["bundled"] to my Cargo.toml file (similar to what is described here - https://users.rust-lang.org/t/linker-cannot-find-lsqlite3/23230/18) as that likely built it from source (which was great) but when I tried doing the same with pcap, it gave the following error:
the package `myProject` depends on `pcap`, with features: `bundled` but `pcap` does not have these features.
After reading somewhere I also tried (with low hopes) of providing the path to the installed libpcap on mac using RUSTPATH='-L/...' cargo build ... but that resulted, of course in undefined symbol errors.
Any ideas how can I get past this issue and cross compile my Rust project into a statically linked binary on macos to run on linux?
Cross compilation does not magically take care of libraries. You cannot just say "I want musl" and have something take care of all your dependencies.
The error message you are seeing is telling you exactly this: it cannot find libsqlite3 and libpcap.
The reason the error for sqlite disappears is because your sqlite library has a bundled feature, which replaces the linking with a built-in sqlite client. This, however, also requests the pcap bundled feature, which does not exist.
You have two options:
If you do not mind the performance loss in the bundled sqlite client, change your feature definition to target the feature of the dependency requiring sqlite
If you want the raw library itself, you will have to compile it for musl
No matter what happens, you will need to cross-compile libpcap for musl with the default sysroot provided by your musl compiler. As this varies per library, you will need to consult the libpcap documentation. once you have done so, you should be able to use the -lpcap flag, and the error will resolve itself.
I'm trying to install gcc4.9 on a SUSE system without an internet connection. I compiled gcc on an Ubuntu machine and installed it into a prefix, then copied the prefix folder to the SUSE machine. When I tried to run it gcc complained about not finding GLIBC_2_14, so I downloaded an rpm for libc6 online and included it into the prefix folders. my LD_LIBRARY_PATH includes prefix/lib and prefix/lib64. When I try to run any program now (ls, cp, cat, etc) I get the error error while loading shared libraries: /home/***/prefix/lib64/libc.so.6: unexpected reloc type 0x25.
Is there any way I can fix this so that I can get gcc4.9 up and running on this system?
As an alternative, is it possible to build gcc staticaly so that I don't have to worry about linking at all when I transfer it between computers?
my LD_LIBRARY_PATH includes prefix/lib and prefix/lib64
See this answer for explanation of why this can't work.
Is there any way I can fix this so that I can get gcc4.9 up and running on this system?
Your best bet is to install whatever GCC package comes with the SuSE system, then use that GCC to configure and install gcc-4.9 on it.
If for some reason you can't do that, this answer has some of the ways in which you can build gcc-4.9 on a newer system and have it still work on an older one.
is it possible to build gcc staticaly so that I don't have to worry about linking at all when I transfer it between computers?
Contrary to popular belief, fully-static binaries are generally less portable then dynamic ones on Linux.
I'm attempting to compile a relatively simple Fortran executable so that it can be passed around to other Windows users that don't have Cygwin (or something of the sort) installed, however, I'm unable to get the executable to operate as a standalone. I've tried gfortran -static file.f and gfortran -static-libgfortran file.f, however other users always encounter this error:
The program can’t start because cygwin1.dll is missing from your computer. Try reinstalling the program to fix this problem.
From what I've read online (e.g. here), the -static option should be sufficient. I have verified that running the executable from my machine (DOS prompt) does work.
I have gcc (gfortran) version 4.7.3. I should also point out this is my first attempt at compiling portable Fortran.
Update
After realizing that this isn't a gfortran-specific issue (thanks to replies here), searches led me to related posts here and here
This is partially explained in the Cygwin FAQ. The solution is to install the mingw64-i686-gcc-fortran package with its dependencies, and cross-compile your code with i686-w64-mingw32-gfortran -static.
Just package the cygwin1.dll along with your binary file (both in the same folder) then it will run just fine.
I am trying to use libfann version 2.0.1 instead of the newest version 2.2.0, but could not figure out how to do so. Any thoughts on how to do that?
normally that works perfectly:
gcc fann_calculator.c -o run_fann_calculator -lfann -lm
where fann_calculator.c contains a program that calls a neural network.
Thanks
It depends upon where the two libraries sit. If they are installed in the same directory (e.g. both installed in /usr/lib/) you'll probably get the youngest one.
I suggest to carefully read the ld.so(8) and ldd(1) man pages. You certainly can trace what library is loaded (with e.g. the LD_DEBUG envirnonment variable). Don't forget to re-run ldconfig appropriately after library installation.
You could also play some LD_LIBRARY_PATH trick; for instance, set it to $HOME/lib:/usr/lib and install appropriate symlinks in your $HOME/lib/ to the precise library you want. For instance, you might do
ln -s /usr/lib/libfann.so.2.0.1 $HOME/lib/libfann.so.2
export LD_LIBRARY_PATH=$HOME/lib:/usr/lib:/lib
then check with ldd run_fann_calculator that you get the expected [version of the] libfann library.
Don't forget to read the Program Library Howto. You might want to pass appropriate flags to ld such as -rpath. You may need to pass them using gcc, perhaps with Gcc Link Options such as -Wl