Linker errors when compiling for ATmega2560 with recent rust compiler (>2022-10-22)

[arnemileswinter]

Hello!

I'm pretty new to cross-compiling.

I created a nix environment in which i can compile the .ELF file for some targets.

For example, the target avr-atmega328p.json works:

bash-5.1$ cargo build --target avr-specs/avr-atmega328p.json 
   Compiling compiler_builtins v0.1.85
   Compiling core v0.0.0 (/nix/store/r9ns07w4z808rpysvg4z84bx3q525yv7-rust-mixed/lib/rustlib/src/rust/library/core)
   Compiling avr-hal-generic v0.1.0 (https://github.com/rahix/avr-hal?rev=4170a773d4d76cc93433d2455ed8b14e573ebe70#4170a7
   [..... i am skipping some lines ....]
   Compiling helloworld v0.1.0 (/home/arne/Projects/hobby/rust-arduino-led-blink)
    Finished dev [optimized + debuginfo] target(s) in 20.01s

And i get target/avr-atmega328p/debug/helloworld.elf.

But the arduino that i have at my disposal is the atmega2560, i get the following output:

bash-5.1$ cargo build --target avr-specs/avr-atmega2560.json --verbose
       Fresh core v0.0.0 (/nix/store/r9ns07w4z808rpysvg4z84bx3q525yv7-rust-mixed/lib/rustlib/src/rust/library/core)
       Fresh rustc-std-workspace-core v1.99.0 (/nix/store/r9ns07w4z808rpysvg4z84bx3q525yv7-rust-mixed/lib/rustlib/src/rust/library/rustc-std-workspace-core)
       Fresh unicode-ident v1.0.6
       Fresh compiler_builtins v0.1.85
       Fresh proc-macro2 v1.0.49
       Fresh quote v1.0.23
       Fresh nb v1.0.0
       Fresh syn v1.0.107
       Fresh proc-macro-hack v0.5.20+deprecated
       Fresh rustversion v1.0.11
       Fresh ufmt-macros v0.2.0
       Fresh avr-device-macros v0.4.0
       Fresh nb v0.1.3
       Fresh ufmt-write v0.1.0
       Fresh bare-metal v1.0.0
       Fresh cfg-if v0.1.10
       Fresh void v1.0.2
       Fresh vcell v0.1.3
       Fresh ufmt v0.1.2
       Fresh paste v1.0.11
       Fresh embedded-hal v0.2.7
       Fresh avr-device v0.4.0
       Fresh cfg-if v1.0.0
       Fresh avr-hal-generic v0.1.0 (https://github.com/rahix/avr-hal?rev=4170a773d4d76cc93433d2455ed8b14e573ebe70#4170a773)
       Fresh panic-halt v0.2.0
       Fresh atmega-hal v0.1.0 (https://github.com/rahix/avr-hal?rev=4170a773d4d76cc93433d2455ed8b14e573ebe70#4170a773)
       Fresh arduino-hal v0.1.0 (https://github.com/rahix/avr-hal?rev=4170a773d4d76cc93433d2455ed8b14e573ebe70#4170a773)
   Compiling helloworld v0.1.0 (/home/arne/Projects/hobby/rust-arduino-led-blink)
     Running `rustc --crate-name helloworld --edition=2021 src/main.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=149 --crate-type bin --emit=dep-info,link -C opt-level=s -C panic=abort -C lto -C debuginfo=2 -C debug-assertions=on -C metadata=fbe7e5f7c81a8527 -C extra-filename=-fbe7e5f7c81a8527 --out-dir /home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps --target /home/arne/Projects/hobby/rust-arduino-led-blink/avr-specs/avr-atmega2560.json -C incremental=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/incremental -L dependency=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps -L dependency=/home/arne/Projects/hobby/rust-arduino-led-blink/target/debug/deps --extern arduino_hal=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/libarduino_hal-b20db3fb6d901e6a.rlib --extern 'noprelude:compiler_builtins=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/libcompiler_builtins-03a22ee3553a16ba.rlib' --extern 'noprelude:core=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/libcore-8e43a845006832d0.rlib' --extern embedded_hal=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/libembedded_hal-2eda8d6ea831d148.rlib --extern nb=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/libnb-1af58d0fb3475ee9.rlib --extern panic_halt=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/libpanic_halt-d2460f22359f919f.rlib --extern ufmt=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/libufmt-a9534496297e0ed1.rlib -Z unstable-options`
error: linking with `avr-gcc` failed: exit status: 1
  |
  = note: LC_ALL="C" PATH="/nix/store/r9ns07w4z808rpysvg4z84bx3q525yv7-rust-mixed/lib/rustlib/x86_64-unknown-linux-gnu/bin:/nix/store/g2nfbpind37b3v3y6zbszmcgfmrj5v7x-patchelf-0.15.0/bin:/nix/store/wn31i3dzwahz6ccws8bs1nwyqrpgsvj7-gcc-wrapper-11.3.0/bin:/nix/store/sxdx80lmk4zkhb51f4x5dgqvxgmx55wl-gcc-11.3.0/bin:/nix/store/s7ip867mrpnnjlppbnxlcsq10gv13x2x-glibc-2.35-224-bin/bin:/nix/store/h8gvq6r4hgpa71h44dmg9qfx03mj81sv-coreutils-9.1/bin:/nix/store/62fb427ncxaaksa2k59rhbilfg68v20x-binutils-wrapper-2.39/bin:/nix/store/frh9l9nrdysasdi2gs7i241s241ngjw2-binutils-2.39/bin:/nix/store/bzc9c4x9fqwjaxs0g45qkahabc0gv75f-avrdude-7.0/bin:/nix/store/fznym4mxp2q5r0bg6zdpska27xcq1iv3-ravedude-0.1.5/bin:/nix/store/r9ns07w4z808rpysvg4z84bx3q525yv7-rust-mixed/bin:/nix/store/88awvrn16car4z5xx516drhpbl2sp5h8-avr-stage-final-gcc-wrapper-11.3.0/bin:/nix/store/7zlcl5m0vq5cl5kcl1swb67wczms78al-avr-stage-final-gcc-11.3.0/bin:/nix/store/5kh0ddszrd1d04z61kw1b2302z7mbnkp-avr-libc-avr-2.1.0/bin:/nix/store/qyrv5scy0pda6cm10mdn66nd6shh907a-avr-binutils-wrapper-2.39/bin:/nix/store/kzjyiw72pi5d7hgyrs0l1fgqq31zj6cs-avr-binutils-2.39/bin:/nix/store/h8gvq6r4hgpa71h44dmg9qfx03mj81sv-coreutils-9.1/bin:/nix/store/zml88vnkpm8if114qkbbqd1q7n3ypqqy-findutils-4.9.0/bin:/nix/store/49y3r0gr9m6k20d91kl6dgp4b9a6m72v-diffutils-3.8/bin:/nix/store/5dv5cq1lwvsijr9p16p2kp79g1dbajk3-gnused-4.8/bin:/nix/store/bcvccw6y9bfil6xrl5j7psza7hnd16ry-gnugrep-3.7/bin:/nix/store/l1fp0hyca54xbb85vfhppd16bskzx8dg-gawk-5.1.1/bin:/nix/store/89zbjdkb48ma61k76l2mzn3s0ra0wn2c-gnutar-1.34/bin:/nix/store/qs8qb1swpivkfq7i9yd52n0mw6z4ij81-gzip-1.12/bin:/nix/store/wwkyfg8b34xy16zzc9p6rkh59p4q37qx-bzip2-1.0.8-bin/bin:/nix/store/i0x4pzj96qwvkrm94317l6jbi53a2rdj-gnumake-4.4/bin:/nix/store/4xw8n979xpivdc46a9ndcvyhwgif00hz-bash-5.1-p16/bin:/nix/store/793iwfbjvg7wgpqq7r83a1qjl1yg02sf-patch-2.7.6/bin:/nix/store/a3mwv26f99ycsv9w6hrx0jjjjywvcb1n-xz-5.2.9-bin/bin:/nix/store/camlh5laf1wsklghk0vcaw7gvx4rpzd1-file-5.43/bin:/home/arne/.nix-profile/bin:/nix/var/nix/profiles/default/bin:/home/arne/.cargo/bin:/home/arne/.nix-profile/bin:/nix/var/nix/profiles/default/bin:/usr/local/bin:/usr/bin:/usr/local/sbin:/usr/lib/jvm/default/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/home/arne/.cabal/bin:/home/arne/.ghcup/bin:/home/arne/.yarn/bin:/home/arne/.emacs.d/bin:/home/arne/.yarn/bin:/home/arne/.emacs.d/bin" VSLANG="1033" "avr-gcc" "-mmcu=atmega2560" "-Wl,--as-needed" "/tmp/nix-shell.pCNOuF/rustcaIPZ4U/symbols.o" "/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/helloworld-fbe7e5f7c81a8527.arduino_hal-b20db3fb6d901e6a.arduino_hal.4ff7873c-cgu.0.rcgu.o.rcgu.o" "-Wl,--as-needed" "-L" "/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps" "-L" "/home/arne/Projects/hobby/rust-arduino-led-blink/target/debug/deps" "-L" "/nix/store/r9ns07w4z808rpysvg4z84bx3q525yv7-rust-mixed/lib/rustlib/avr-atmega2560/lib" "-Wl,-Bstatic" "/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/libcompiler_builtins-03a22ee3553a16ba.rlib" "-Wl,-Bdynamic" "-lgcc" "-Wl,-znoexecstack" "-L" "/nix/store/r9ns07w4z808rpysvg4z84bx3q525yv7-rust-mixed/lib/rustlib/avr-atmega2560/lib" "-o" "/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/helloworld-fbe7e5f7c81a8527.elf" "-Wl,--gc-sections" "-no-pie"
  = note: /nix/store/kzjyiw72pi5d7hgyrs0l1fgqq31zj6cs-avr-binutils-2.39/bin/avr-ld: skipping incompatible /nix/store/5kh0ddszrd1d04z61kw1b2302z7mbnkp-avr-libc-avr-2.1.0/avr/lib/avr5/libm.a when searching for -lm
          /nix/store/kzjyiw72pi5d7hgyrs0l1fgqq31zj6cs-avr-binutils-2.39/bin/avr-ld: skipping incompatible /nix/store/5kh0ddszrd1d04z61kw1b2302z7mbnkp-avr-libc-avr-2.1.0/avr/lib/avr3/libm.a when searching for -lm
          /nix/store/kzjyiw72pi5d7hgyrs0l1fgqq31zj6cs-avr-binutils-2.39/bin/avr-ld: skipping incompatible /nix/store/5kh0ddszrd1d04z61kw1b2302z7mbnkp-avr-libc-avr-2.1.0/avr/lib/avr4/libm.a when searching for -lm
          /nix/store/kzjyiw72pi5d7hgyrs0l1fgqq31zj6cs-avr-binutils-2.39/bin/avr-ld: skipping incompatible /nix/store/5kh0ddszrd1d04z61kw1b2302z7mbnkp-avr-libc-avr-2.1.0/avr/lib/avr5/libc.a when searching for -lc
          /nix/store/kzjyiw72pi5d7hgyrs0l1fgqq31zj6cs-avr-binutils-2.39/bin/avr-ld: skipping incompatible /nix/store/5kh0ddszrd1d04z61kw1b2302z7mbnkp-avr-libc-avr-2.1.0/avr/lib/avr3/libc.a when searching for -lc
          /nix/store/kzjyiw72pi5d7hgyrs0l1fgqq31zj6cs-avr-binutils-2.39/bin/avr-ld: skipping incompatible /nix/store/5kh0ddszrd1d04z61kw1b2302z7mbnkp-avr-libc-avr-2.1.0/avr/lib/avr4/libc.a when searching for -lc
          /nix/store/kzjyiw72pi5d7hgyrs0l1fgqq31zj6cs-avr-binutils-2.39/bin/avr-ld: avr architecture of input file `/tmp/nix-shell.pCNOuF/rustcaIPZ4U/symbols.o' is incompatible with avr:6 output
          collect2: error: ld returned 1 exit status
          

error: could not compile `helloworld` due to previous error

Caused by:
  process didn't exit successfully: `rustc --crate-name helloworld --edition=2021 src/main.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=149 --crate-type bin --emit=dep-info,link -C opt-level=s -C panic=abort -C lto -C debuginfo=2 -C debug-assertions=on -C metadata=fbe7e5f7c81a8527 -C extra-filename=-fbe7e5f7c81a8527 --out-dir /home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps --target /home/arne/Projects/hobby/rust-arduino-led-blink/avr-specs/avr-atmega2560.json -C incremental=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/incremental -L dependency=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps -L dependency=/home/arne/Projects/hobby/rust-arduino-led-blink/target/debug/deps --extern arduino_hal=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/libarduino_hal-b20db3fb6d901e6a.rlib --extern 'noprelude:compiler_builtins=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/libcompiler_builtins-03a22ee3553a16ba.rlib' --extern 'noprelude:core=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/libcore-8e43a845006832d0.rlib' --extern embedded_hal=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/libembedded_hal-2eda8d6ea831d148.rlib --extern nb=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/libnb-1af58d0fb3475ee9.rlib --extern panic_halt=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/libpanic_halt-d2460f22359f919f.rlib --extern ufmt=/home/arne/Projects/hobby/rust-arduino-led-blink/target/avr-atmega2560/debug/deps/libufmt-a9534496297e0ed1.rlib -Z unstable-options` (exit status: 1)

I don't understand why it doesn't work for the latter target.

The repository is here: https://github.com/arnemileswinter/rust-arduino-cross-compile-nix-blinking-led
and is based on the cargo template.

Thanks in advance!

[Patryk27]

It looks like something on the way (rustc, llvm or avr-gcc?) doesn't like AVR6 as an architecture - which is weird, since in principle everything should be compatible with it.

I've checked avr-binutils (as a fellow NixOS user) and it seems that AVR6's standard library is present there, and the symbols.o file mentioned in the error message seems to get generated identically for AVR5 (e.g. atmega328p) and AVR6 (e.g. atmega2560) - maybe when rustc generates this file it doesn't set some "compatible with avr6" flag?

(I haven't checked other systems, though - maybe it's a NixOS specific thing related to how it packages avr-gcc, for instance.)

[PaulRaUnite]

Hello, I am struggling with the same error. I tried a bunch of nightly versions and it seems something broke in nightly-2022-10-23 (rust version 1.66.0-nightly (6e95b6da8 2022-10-22)) as nightly-2022-10-22 works.

So, you should try to change your channel field in rust-toolchain.toml to nightly-2022-10-22, and I think it will work.

[arnemileswinter]

@PaulRaUnite fixed it!

My repository now has a working nix-powered development environment.

https://github.com/arnemileswinter/rust-atmega2560-cross-compile-nix-blinking-led

I am unsure whether we should close this issue now until the upstream error in nightly is fixed, or if this can be closed.

[Rahix]

Let's keep it open for visibility. Is there an upstream issue we can link to?

[agausmann]

I am having the same issue with attiny404 when trying to compile #357 on latest nightly. Can also confirm that something happened between 2022-10-22 and 2022-10-23 nightlies

[agausmann]

Bisecting leads to rust-lang/rust@5642a75 as the first commit with this issue.

[agausmann]

Prior to this commit, symbols.o would not be created at all.

The function add_linked_symbol_object is responsible for creating symbols.o file, but there is an early return if create_object_file returns None (which it did before the mentioned commit, which adds support for AVR in create_object_file)

We still need to figure out why the generated object file's architecture is incompatible and how to correct it, but the create_object_file function is a good place to start looking.

My guess is that there is some field in the ELF file that is conventionally used to specify the AVR MCU, and the linker is checking that field but rustc doesn't set it correctly.

[agausmann]

I was close - the low 7 bits of e_flags in the ELF header are the "ISA revision", which isn't exactly the same as the MCU:

#define EF_AVR_MACH 0x7F
#define E_AVR_MACH_AVR1     1
#define E_AVR_MACH_AVR2     2
#define E_AVR_MACH_AVR25   25
#define E_AVR_MACH_AVR3     3
#define E_AVR_MACH_AVR31   31
#define E_AVR_MACH_AVR35   35
#define E_AVR_MACH_AVR4     4
#define E_AVR_MACH_AVR5     5
#define E_AVR_MACH_AVR51   51
#define E_AVR_MACH_AVR6     6
#define E_AVR_MACH_AVRTINY 100
#define E_AVR_MACH_XMEGA1  101
#define E_AVR_MACH_XMEGA2  102
#define E_AVR_MACH_XMEGA3  103
#define E_AVR_MACH_XMEGA4  104
#define E_AVR_MACH_XMEGA5  105
#define E_AVR_MACH_XMEGA6  106
#define E_AVR_MACH_XMEGA7  107

(Copied from binutils-2.39/include/elf/avr.h)

The e_flags field should probably be set to one of these values in create_object_file, since that is already done for some other target architectures.