f29a5497f5
In Cargo, it is quite typical for "build scripts" to be written in Rust
and therefore they need to be compiled as part of the overall build. In
cross-compilation, that means a mixed host and target build.
Unfortunately, by default Cargo makes no distinction between the
RUSTFLAGS used for the host and the target. There is, however, an
unstable feature to make this distinction [1][2].
We already have CARGO_TARGET_APPLIES_TO_HOST="false". This makes sure
that any configuration that we make for the target doesn't automatically
apply to the host as well. However, this only applies for per-target
configuration, for example the setting of "cc" in the config.toml
generated by package/rust/rust.mk. Flags that are passed with RUSTFLAGS
still apply to both host and target. Therefore, we need to use the
CARGO_TARGET_<tuple>_RUSTFLAGS environment variable instead of plain
RUSTFLAGS.
This, however, doesn't allow us to specify flags that apply only to the
host. We could use CARGO_TARGET_<hosttuple>_RUSTFLAGS for that, but that
doesn't work in case the host and target tuple are the same. For this,
we need another unstable feature, enabled with
CARGO_UNSTABLE_HOST_CONFIG="true". With this enabled, we can specify
flags that apply only for the host build using CARGO_HOST_RUSTFLAGS.
Currently, we don't have any such flags, but we really should: we should
pass the proper link flags to point to $(HOST_DIR)/lib. Therefore, add
CARGO_HOST_RUSTFLAGS doing exactly that.
[1] https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#host-config
[2] https://github.com/rust-lang/cargo/pull/10395
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>
(cherry picked from commit
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| boot | ||
| configs | ||
| docs | ||
| fs | ||
| linux | ||
| package | ||
| support | ||
| system | ||
| toolchain | ||
| utils | ||
| .checkpackageignore | ||
| .clang-format | ||
| .defconfig | ||
| .flake8 | ||
| .gitignore | ||
| .gitlab-ci.yml | ||
| .shellcheckrc | ||
| CHANGES | ||
| Config.in | ||
| Config.in.legacy | ||
| COPYING | ||
| DEVELOPERS | ||
| Makefile | ||
| Makefile.legacy | ||
| README | ||
Buildroot is a simple, efficient and easy-to-use tool to generate embedded Linux systems through cross-compilation. The documentation can be found in docs/manual. You can generate a text document with 'make manual-text' and read output/docs/manual/manual.text. Online documentation can be found at http://buildroot.org/docs.html To build and use the buildroot stuff, do the following: 1) run 'make menuconfig' 2) select the target architecture and the packages you wish to compile 3) run 'make' 4) wait while it compiles 5) find the kernel, bootloader, root filesystem, etc. in output/images You do not need to be root to build or run buildroot. Have fun! Buildroot comes with a basic configuration for a number of boards. Run 'make list-defconfigs' to view the list of provided configurations. Please feed suggestions, bug reports, insults, and bribes back to the buildroot mailing list: buildroot@buildroot.org You can also find us on #buildroot on OFTC IRC. If you would like to contribute patches, please read https://buildroot.org/manual.html#submitting-patches