RTEMS 4.9.4 On-Line Library

Port Specific Information Floating Point Unit

RTEMS CPU Architecture Supplement

1.1.2: Floating Point Unit

In most architectures, the presence of a floating point unit is an option. It does not matter whether the hardware floating point support is incorporated on-chip or is an external coprocessor as long as it appears an FPU per the ISA. However, if a hardware FPU is not present, it is possible that the floating point emulation library for this CPU is not reentrant and thus context switched by RTEMS.

RTEMS provides two feature macros to indicate the FPU configuration:

CPU_HARDWARE_FP is set to TRUE to indicate that a hardware FPU is present.
CPU_SOFTWARE_FP is set to TRUE to indicate that a hardware FPU is not present and that the FP software emulation will be context switched.

RTEMS CPU Architecture Supplement