%general-entities; ]> On the ARM architecture, there are two major ABI types to choose from: EABI and OABI. There is also a Thumb ABI and an Intel IWMMX specific ABI but these are generally not recommended for most uses. The EABI (Embedded ABI) is newer and supports additional features, faster software floating point operations, and Thumb interworking, but is only compatible with ARMv4t and newer cores. The EABI has sub-ABIs of: aapcs-linux and aapcs. aapcs-linux has standard Linux 4 byte enums while aapcs has variable length enums. aapcs-linux is recommended over aapcs. The OABI (old ABI) is called apcs-gnu and supports ARMv4 and older cores. Generally the OABI is not used by modern ARM processors. ABI Note aapcs-linux Recommended for EABI. Standard Linux 32 bit (int) enums apcs-gnu Recommended for OABI atpcs Thumb ABI aapcs EABI w/ variable size enums iwmmxt Supports Intel XScale MMX extensions