On 01.02.25 12:42 AM, Christian Schrefl wrote: > On 31.01.25 8:37 PM, Arnd Bergmann wrote: >> On Fri, Jan 31, 2025, at 19:58, Christian Schrefl wrote: >>> On 31.01.25 5:05 PM, Andrew Lunn wrote: >>>>> To fix this Rust would have to provide a way to build the core >>>>> library without float support. I don't know if there is a plan >>>>> already to allow this. >>>> >>>> Floating point is banned within the kernel, except for in very narrow >>>> conditions, because the floating point registers are lazy saved on >>>> context switch. If the kernel uses the floating point registers, you >>>> can break user space in bad ways. >>>> >>>> I expect this has been discussed, since it is well known kernel >>>> restriction. Maybe go see what happened to that discussion within RfL? >>> >>> After checking again, it seems the float intrinsics are actually not >>> needed anymore at least for my config. >> >> Ah, nice! If this is true for all architectures using the current >> rust compiler, it would be great to remove the FP stubs entirely >> and have link errors instead of panicking, to make it consistent >> with C. > > After a quick test it seems that (most?) intrinsics are not needed > anymore on x86, but not sure if that's valid for all supported rust > versions and config options. On Rust 1.84.1 only __udivti3 is requied, with 1.78 most of the intrinsics seem to still be required. Cheers Christian
