ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition

Deprecated and Obsolete Features
D.1 Deprecated features
The features described in this section are present in ARMv7 for backwards compatibility. You must avoid
using them in new applications where possible. They might not be present in future versions of the ARM
architecture.
See also Semaphore instructions on page AppxD-7, Use of the SP as a general-purpose register on
page AppxD-8, and Explicit use of the PC in ARM instructions on page AppxD-9.
D.1.1 VFP vector mode
The use of VFP vector mode is deprecated in ARMv7. For details see Appendix F VFP Vector Operation
Support.
D.1.2 VFP FLDMX and FSTMX instructions
The use of VLDM.64 and VSTM.64 instruction encodings with an odd immediate offset is deprecated from
ARMv6. The use of their pre-UAL mnemonics FLDMX and FSTMX is deprecated, except for disassembly
purposes. For details see FLDMX, FSTMX on page A8-101.
D.1.3 Fast context switch extension
Use of the Fast Context Switch Extension (FCSE) is deprecated from ARMv6, and in ARMv7
implementation of the FCSE is optional. For details of the FCSE see Appendix E Fast Context Switch
Extension (FCSE).
D.1.4 Direct manipulation of the Endianness bit
The use of the MSR instruction to write the Endianness bit in User mode is deprecated. Use the SETEND
instruction.
D.1.5 Strongly-ordered memory accesses and interrupt masks
Any ARMv5 instruction that implicitly or explicitly changes the interrupt masks in the CPSR, and appears
in program order after a Strongly-ordered access, waits for the Strongly-ordered memory access to
complete. Dependence on this behavior is deprecated in ARMv6 and ARMv7, and code must not rely on
this behavior. Use an explicit memory barrier instead. For details see Strongly-ordered memory on
page A3-34.
D.1.6 Unaligned exception returns
ARM deprecates any dependence on the requirements that the hardware ignores bits of the address
transferred to the PC on an exception return. See Alignment of exception returns on page B1-39.
AppxD-2 Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. ARM DDI 0406B