Using nix to build ARTIQ-4 gateware from an external ARTIQ-based library

bradb

I'm currently working with code from the UMD EURIQA team and have forked nix-scripts and added their package to the building process (via making a nix file in artiq-fast/pkgs and adding a couple of python deps, then adding the package to default.nix). I'm building with ARTIQ release-4 and the changes discussed in #1346. I've got the package to build and install correctly as far as I can tell, and am now trying to add one of their gateware builds. I added it in artiq-full.nix in the same way that the sayma builds at the end are added (with artiq-board), but with a different build command (python -m euriqabackend.gateware.kc705_soc). I was hoping that I could just use artiq-board, but I'm running into the following error:

<3>make: Entering directory '/build/artiq4_kc705_euriqa/euriqa/software/bootloader'
<3> CARGO    cargo/or1k-unknown-none/debug/libbootloader.a
<3>error: failed to load source for a dependency on `smoltcp`
<3>
<3>Caused by:
<3>  Unable to update https://github.com/m-labs/smoltcp?rev=92e970b#92e970b3
<3>
<3>Caused by:
<3>  failed to open: /nix/store/mnymfg3c4fw1qzhgzhbgyr1in89yxa03-artiq-firmware-cargo-vendored/git/.cargo-lock-git
<3>
<3>Caused by:
<3>  Permission denied (os error 13)
<3>make: *** [Makefile:10: cargo/or1k-unknown-none/debug/libbootloader.a] Error 101
<3>make: Leaving directory '/build/artiq4_kc705_euriqa/euriqa/software/bootloader'
<3>Command make -C /build/artiq4_kc705_euriqa/euriqa/software/bootloader failed
<3>builder for '/nix/store/j5j9n1rkpjp30r17rqpvvmzkfvq1157j-artiq-board-kc705-euriqa-4.6403.7cf25f85.beta.drv' failed with exit code 1

I also noticed that the folder "/git" doesn't exist when I manually check following the error, but that doesn't match up with a permissions error, so I'm not entirely sure what the actual problem is.

@sb10q has suggested that it may be a cargoSha256 mismatch, but I'm not sure how to verify that, or how to fix it if that is the case.

sb10q

When Rust programs are built with Nix, cargo dependencies are downloaded by a fixed-output derivation and "vendored" so that cargo does not try to download them itself during the build (which it obviously attempts to do according to your log).
A probable reason is you are still using the cargoSha256 value (which is the hash of the fixed-output derivation) from ARTIQ-5, so you are getting the wrong crates vendored and cargo attempts to download others during the build.

bradb

So how should I go about fixing it? Do I just need to change the sha value (and if so, where do I find the correct one)? Or do I need to change the versions of the cargo/rust-related packages too?

bradb

Okay after looking at the generated registry/Cargo.toml, it seems that smoltcp 0.5.0 is still being used, as opposed to 0.4.0 (?) in ARTIQ release-4. I've figured out how to reproduce the sha256 for cargoDeps in artiq-board, and it hasn't changed for this build, so I assume that means that it's using all the same packages as for ARTIQ 5. How do I change the version used for smoltcp (I'm not sure if that's the only dependency that has changed, but it's a place to start)? I don't see any reference to smoltcp or any of the specific dependencies in the nix-scripts code.

bradb

Or am I thinking about this the wrong way, and changing the sha256 will change the package versions downloaded in the fixed-output derivation? In which case, we're back to my original question, which is how to find the correct sha.

bradb

Update: figured it out. Added cargo-vendor to shell-dev, ran $cargo vendor from the release-4 firmware directory, got the hash of the output, and added the appropriate lines to the config file.