Level 2 Memory Interface
ARM DDI 0388I
Copyright © 2008-2012 ARM. All rights reserved.
8-9
ID073015
Non-Confidential
8.3
STRT instructions
Take particular care with noncacheable write accesses when using the
STRT
instruction. To put
the correct information on the external bus ensure one of the following:
•
The access is to Strongly-ordered memory.
This ensures that the
STRT
instruction does not merge in the store buffer.
•
The access is to Device memory.
This ensures that the
STRT
instruction does not merge in the store buffer.
•
A
DSB
instruction is issued before and after the
STRT
.
This prevents an
STRT
from merging into an existing slot at the same 64-bit address, or
merging with another write at the same 64-bit address.
shows Cortex-A9 modes and corresponding
AxPROT
values.
Table 8-6 Cortex-A9 mode and AxPROT values
Processor mode
Type of access
Value of AxPROT
User
Cacheable read access
User
Privileged
Privileged
User
Noncacheable read access
User
Privileged
Privileged
-
Cacheable write access
Always marked as Privileged
User
Noncacheable write access
User
Privileged
Noncacheable write access
Privileged, except when using
STRT