Link error in stage1

[jokade]

Hi, I tried to compile your branch avr-support with

./configure --prefix=/opt/local/avrrust && make

which results in a link error (for stage1?):

error: linking with `cc` failed: exit code: 1
note: cc '-m64' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-o' 'x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib/librustc-4e7c5e5c.dylib' 'x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib/rustc-4e7c5e5c.o' '-Wl,-force_load,/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib/libmorestack.a' 'x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib/rustc-4e7c5e5c.metadata.o' '-fno-lto' '-Wl,-dead_strip' '-nodefaultlibs' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-lgraphviz-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-lgetopts-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-lrustc_llvm-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-lrustc_back-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-lsyntax-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-lterm-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-lfmt_macros-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-larena-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-lrbml-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-ltime-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-lserialize-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-llog-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-lregex-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-lflate-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-lstd-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-lsync-4e7c5e5c' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib' '-lrustrt-4e7c5e5c' '-L' 'x86_64-apple-darwin/rt' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/x86_64-apple-darwin/llvm/Release+Asserts/lib' '-L' '.' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust/.rust' '-L' '/Volumes/JKDATA/dev/tmp/avr-rust' '-lpthread' '-ledit' '-lm' '-lc++' '-lSystem' '-lpthread' '-lc' '-lm' '-dynamiclib' '-Wl,-dylib' '-lcompiler-rt'
note: ld: warning: directory not found for option '-L/Volumes/JKDATA/dev/tmp/avr-rust/.rust'
Undefined symbols for architecture x86_64:
  "_LLVMInitializeAVRTargetInfo", referenced from:
      back::write::configure_llvm::closure.105122 in rustc-4e7c5e5c.o
  "_LLVMInitializeAVRTarget", referenced from:
      back::write::configure_llvm::closure.105122 in rustc-4e7c5e5c.o
  "_LLVMInitializeAVRTargetMC", referenced from:
      back::write::configure_llvm::closure.105122 in rustc-4e7c5e5c.o
  "_LLVMInitializeAVRAsmPrinter", referenced from:
      back::write::configure_llvm::closure.105122 in rustc-4e7c5e5c.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

error: aborting due to previous error
make: *** [x86_64-apple-darwin/stage0/lib/rustlib/x86_64-apple-darwin/lib/stamp.rustc] Error 101

Do I need addtional config flags? thx

[dylanmckay]

Ah yes, I was intending to fix this but it slipped my mind.

Rust knows about all of those functions, and calls them, but it isn't linking to the static libraries (libLLVMAVRCodeGen.a, etc).

A quick fix is to add these lines to rust/src/librustc_llvm/llvmdeps.rs" and recompile

#[link(name = "LLVMAVRCodeGen", kind = "static")]
#[link(name = "LLVMAVRDesc", kind = "static")]
#[link(name = "LLVMAVRInfo", kind = "static")]
#[link(name = "LLVMAVRAsmPrinter", kind = "static")]

I believe the fix for this is to add avr to the LLVM_COMPONENTS variable in rust/mk/main.mk here, which I will do now. It used to be there, but it would cause an error (LLVM_COMPONENTS is passed to the llvm-config program which then outputs all of the libraries which are needed to be linked against for all of the components. It used to say unknown component: avr or something to that effect.

[dylanmckay]

I have now added avr to LLVM_COMPONENTS and am waiting for Rust to compile afresh before I push the change. Note that my laptop is fairly low-end, and Rust doesn't have particularly fast compilation times, so give it an hour or two, perhaps three :)

[jokade]

Great, rust now compiles with your fix :-)
However, how do I set the target architecture to avr? Don't I need to compile the rust libraries for target avr (it seems to me, that without further config flags, all libraries are built for my host architecture)?
When I try to compile a rust file with

rust test.rs

I get a link error:

error: linking with `cc` failed: exit code: 1
note: cc '-m64' '-L' '/opt/local/avrrust/lib/rustlib/x86_64-apple-darwin/lib' '-o' 'test' 'test.o' '-Wl,-force_load,/opt/local/avrrust/lib/rustlib/x86_64-apple-darwin/lib/libmorestack.a' '-fno-lto' '-Wl,-dead_strip' '-nodefaultlibs' '/opt/local/avrrust/lib/rustlib/x86_64-apple-darwin/lib/libnative-4e7c5e5c.rlib' '/opt/local/avrrust/lib/rustlib/x86_64-apple-darwin/lib/libstd-4e7c5e5c.rlib' '/opt/local/avrrust/lib/rustlib/x86_64-apple-darwin/lib/libsync-4e7c5e5c.rlib' '/opt/local/avrrust/lib/rustlib/x86_64-apple-darwin/lib/librustrt-4e7c5e5c.rlib' '/opt/local/avrrust/lib/rustlib/x86_64-apple-darwin/lib/librand-4e7c5e5c.rlib' '/opt/local/avrrust/lib/rustlib/x86_64-apple-darwin/lib/libcollections-4e7c5e5c.rlib' '/opt/local/avrrust/lib/rustlib/x86_64-apple-darwin/lib/libunicode-4e7c5e5c.rlib' '/opt/local/avrrust/lib/rustlib/x86_64-apple-darwin/lib/liballoc-4e7c5e5c.rlib' '/opt/local/avrrust/lib/rustlib/x86_64-apple-darwin/lib/liblibc-4e7c5e5c.rlib' '/opt/local/avrrust/lib/rustlib/x86_64-apple-darwin/lib/libcore-4e7c5e5c.rlib' '-L' '/Volumes/JKDATA/dev/tmp/rust/.rust' '-L' '/Volumes/JKDATA/dev/tmp/rust' '-lSystem' '-lpthread' '-lc' '-lm' '-lcompiler-rt'
note: ld: warning: directory not found for option '-L/Volumes/JKDATA/dev/tmp/rust/.rust'
ld: can't open output file for writing: test, errno=21 for architecture x86_64

[dylanmckay]

Take a look at README.md, and the example source enclosed within. Basically:

To set the target architecture to AVR, pass --target=avr-none (none being the OS by the way). Because currently only outputting assembly is possible, pass --emit asm as well. Also, to get around a bug (#1), optimization must also be turned on: pass -O

For example:

rustc hello_world.rs --target=avr-none -O --emit asm

Good luck!

[dylanmckay]

Note that the quick fix should no longer be necessary after deleting the old /rust/src/librustc_llvm/llvmdeps.rs and reconfiguring and rebuilding, or simply just recloning the repository and compiling with the latest commit.

[jokade]

Sorry, I didn't notice that you've updated the README...
It works fine now... Thanks!

[dylanmckay]

You are right about the standard library not being built for AVR. Obviously a portion of it will not be possible (io/mutexes/etc), but hopefully the libraries are structured in such a way to make porting to Rust a tractable problem.

I have very recently created a new repo which aims to catalog details about the hordes of AVR variants. I have already written a tool to parse the Atmel io/io___.h headers for register information for each board, and generate a JSON format description of it. Currently, the Atmega328p exists in it. I also have another repo which provides a Rust API for reading the JSON register information, which I am to use to generate Rust source files which define all of the available registers for each CPU.

Imagine:

// io/atmega328p.rs
const DDRB: *mut u8 = 0x04;
const PORTB: *mut u8 = 0x05;

Once that exists, it would be easy to write various abstractions over CPUs. After I have written this, I will then endeavor to get the standard library (well, as much as I can) working for AVR.

I haven't had access to an AVR for several days and so avr-rust is untested in the purest sense of the word, so keep me updated!

[dylanmckay]

Let's move discussion to #3