Re: [Buildroot] [PATCH v2 2/2] package/dtui: require 64-bit atomic support

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

Hello,

On Mon, Aug 31, 2026 at 04:49:58PM +0100, Christopher Obbard via buildroot wrote:
> dtui depends on tui-textarea which unconditionally imports AtomicU64 in
> src/widget.rs to pack a viewport rectangle into a single atomic word:
> 
>   use std::sync::atomic::{AtomicU64, Ordering};
>   pub struct Viewport(AtomicU64);
> 
> As there is no cfg(target_has_atomic) guard in tui-textarea, its
> build fails on any target for which rustc does not provide 64-bit
> atomics with:
> 
>   Compiling tui-textarea v0.7.0
>   error[E0432]: unresolved import `std::sync::atomic::AtomicU64`
>     --> .../dtui-3.0.0/VENDOR/tui-textarea/src/widget.rs:10:25
>      |
>   10 | use std::sync::atomic::{AtomicU64, Ordering};
>      |                         ^^^^^^^^^ no `AtomicU64` in `sync::atomic`
>      |
>   help: a similar name exists in the module
>      |
>   10 - use std::sync::atomic::{AtomicU64, Ordering};
>   10 + use std::sync::atomic::{AtomicU32, Ordering};
> 
> This has been reported to tui-textarea upstream, but unfortunately the
> project seems to be unmaintained (issue linked below). A sane workaround
> is to disable the package on targets which lack 64-bit atomic support,
> which is exactly what BR2_PACKAGE_HOST_RUSTC_TARGET_HAS_ATOMIC_64
> describes: it is n for armv5te-unknown-linux-{gnu,musl}eabi and
> powerpc-unknown-linux-gnu, the only rust targets Buildroot can generate
> which lack 64-bit atomics, and y everywhere else.
> 
> The same problem was hit by package/dust and worked around in commit
> 3abc3b97bad9 ("package/dust: bump to version 1.1.2") by bumping to a
> version in which upstream had added the missing guard. That is not an
> option here as tui-textarea 0.7.0 is the latest release.
> 
> Note that a runtime test for dtui cannot use the default
> infra.basetest.BASIC_TOOLCHAIN_CONFIG, since that builds with
> BR2_TOOLCHAIN_EXTERNAL_BOOTLIN_ARMV5_EABI_GLIBC_STABLE, where dtui is now
> disabled; such a test would need an armv7 or aarch64 toolchain instead.
> 
> Build tested with utils/test-pkg against:
> - BR2_TOOLCHAIN_EXTERNAL_BOOTLIN_ARMV5_EABI_GLIBC_STABLE
> - BR2_TOOLCHAIN_EXTERNAL_BOOTLIN_ARMV5_EABI_MUSL_STABLE
> - BR2_TOOLCHAIN_EXTERNAL_BOOTLIN_POWERPC_E500MC_GLIBC_STABLE
> 
> all three fail with the above error before this change and are skipped
> after it, while armv7 (glibc and musl), aarch64, powerpc64le and x86-64
> still select and build the package.
> 
> Link: https://github.com/rhysd/tui-textarea/issues/66
> Fixes: https://autobuild.buildroot.org/results/188f6442371500731453f75983590c922eab6d57
> Fixes: https://autobuild.buildroot.org/results/e254db2654f18f1d2110eb8b1a32b43ad0f2a3d6
> Signed-off-by: Christopher Obbard <chris.obbard@oss.qualcomm.com>

Thanks, applied after:

- Renaming the symbol

- Adding the "depends on" also to the Config.in comment so that the
  comment doesn't appear on CPU architectures where dtui will anyway
  not be available

Thanks a lot!

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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