bootc fails to build on armv7

[mtudan]

Hello,

I know armv7 is considered somewhat obsolete, but there are still many boards out there worth maintaining especially because of their price point. Anyhow, I was trying to build bootc for armv7, and while all other dependencies seem to build fine, it failed at bootc-lib:

967.7    Compiling uapi-version v0.4.0
968.9    Compiling indoc v2.0.7
973.5    Compiling tini v1.3.0
1034.2    Compiling ostree v0.20.5
1055.7    Compiling ostree-ext v0.15.3 (/bootc/crates/ostree-ext)
1094.0    Compiling bootc-lib v1.12.1 (/bootc/crates/lib)
1097.2 error: Unsupported architecture
1097.2    --> crates/lib/src/discoverable_partition_specification.rs:523:13
1097.2     |
1097.2 523 |             compile_error!("Unsupported architecture")
1097.2     |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1097.2
1157.8 error: could not compile `bootc-lib` (lib) due to 1 previous error
1157.8 error: Generating manpages: Syncing man pages: Extracting CLI: Running CLI JSON dump command: command exited with non-zero code `cargo run --features=docgen -- internals dump-cli-json`: 101
1157.8 make: *** [Makefile:44: manpages] Error 1
1157.8 make: Leaving directory '/bootc'

Steps to reproduce:

FROM --platform=linux/arm ubuntu:questing AS bootc-builder
ARG DEBIAN_FRONTEND=noninteractive
ENV CARGO_HOME=/opt/rust
ENV RUSTUP_HOME=/opt/rust

RUN apt update -y && \
    apt install -y git curl make build-essential go-md2man libzstd-dev pkgconf dracut libostree-dev ostree && \
    curl --proto '=https' --tlsv1.2 -sSf "https://sh.rustup.rs" | sh -s -- --profile minimal -y && \
    git clone "https://github.com/bootc-dev/bootc.git" /bootc && \
    sh -c ". ${RUSTUP_HOME}/env ; make -C /bootc bin DESTDIR=/bootc-install install-all"

Build command:

docker build . -t bootc-armv7 --platform linux/arm

I just wanted to check with you if this is something worth diving deeper into.

[mtudan]

Turns out everything else is in place, and there was just a simple check missing in the this_arch_root(): #1971