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

ARMv6 Differences
For ARMv6, TLB lockdown must comply with one of the lockdown models described in c10, VMSA TLB
lockdown support on page AppxH-59.
G.7.19 c11, DMA support
The ARMv6 DMA support for TCMs described in The ARM Architecture Reference Manual (DDI 0100) is
considered IMPLEMENTATION DEFINED and not included in this manual. ARMv6 is therefore the same as
ARMv7. See CP15 c11, Reserved for TCM DMA registers on page B3-147.
G.7.20 c12, VMSA support for the Security Extensions
CP15 c12 support for the Security Extensions in ARMv6 is the same as in ARMv7:
the Vector Base Address Register, VBAR
the Monitor Base Address Register, MVBAR
the Interrupt Status Register, ISR.
For details see CP15 c12, Security Extensions registers on page B3-148.
G.7.21 c13, Context ID support
Both PMSAv6 and VMSAv6 require the CONTEXTIDR described in:
c13, Context ID Register (CONTEXTIDR) on page B3-153, for a VMSA implementation
c13, Context ID Register (CONTEXTIDR) on page B4-76, for a PMSA implementation.
In addition:
A VMSAv6 implementation requires the FCSEIDR, described in c13, FCSE Process ID Register
(FCSEIDR) on page B3-152. In ARMv6 the FCSE must be implemented. For more information, see
Appendix E Fast Context Switch Extension (FCSE).
An ARMv6K implementation requires the Software Thread ID registers described in CP15 c13
Software Thread ID registers on page B3-154.
Note
In ARMv6, after any change to the CONTEXTIDR or FCSEIDR, software must use the CP15 branch
predictor maintenance operations to flush the virtual addresses affected by the change. If the branch
predictor is not invalidated in this way, attempting to execute an old branch might cause UNPREDICTABLE
behavior. ARMv7 does not require branch predictors to be invalidated after a change to the CONTEXTIDR
or FCSEIDR.
G.7.22 c15, IMPLEMENTATION DEFINED
As in ARMv7, CP15 c15 is reserved for IMPLEMENTATION DEFINED use. Typically, it is used for
processor-specific runtime and test features.
AppxG-54 Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. ARM DDI 0406B