I've seen this a lot in Texas Instruments' bare-metal BSPs for their processors that are generated using HalCoGen. Their own proprietary compiler handles them a

I've seen this a lot in Texas Instruments' bare-metal BSPs for their processors that are generated using HalCoGen. Their own proprietary compiler handles them as you'd expect. Other BSPs typically follow the coding style for their operating system. I've never seen QNX BSP drivers use bitfields. I've also never seen them in Linux drivers. QNX and Linux typically use variants of GCC to compile their drivers unless you pay for another toolchain.