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`armv7r-none-eabi*` and `thumbv7r-none-eabi*`

src/doc/rustc/src/platform-support/armv7r-none-eabi.md

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armv7r-none-eabi* and thumbv7r-none-eabi*

  • Tier: 2
  • Library Support: core and alloc (bare-metal, #![no_std])

Bare-metal target for CPUs in the Armv7-R architecture family, supporting dual ARM/Thumb mode. The armv7r-none-eabi* targets use Arm mode by default and the thumbv7r-none-eabi* targets use Thumb mode by default. The -eabi targets use a soft-float ABI and do not require an FPU, while the -eabihf targets use a hard-float ABI and do require an FPU.

Processors in this family include the Arm Cortex-R4, 5, 7, and 8.

See arm-none-eabi for information applicable to all arm-none-eabi targets.

Target maintainers

Requirements

When using the hardfloat (-eabibf) targets, the minimum floating-point features assumed are those of the vfpv3-d16, which includes single- and double-precision, with 16 double-precision registers. This floating-point unit appears in Cortex-R4F and Cortex-R5F processors. See VFP in the Cortex-R processors for more details on the possible FPU variants.

If your processor supports a different set of floating-point features than the default expectations of vfpv3-d16, then these should also be enabled or disabled as needed with -C target-feature=(+/-).

Start-up and Low-Level Code

The Rust Embedded Devices Working Group Arm Team maintain the aarch32-cpu and aarch32-rt crates, which may be useful for writing bare-metal code using this target. Those crates include several examples which run in QEMU and build using these targets.