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ARMv8 mm_region type

发布时间:2016年12月07日评论数：抢沙发阅读数：16893

Attachment: Programmer’s Guide for ARMv8-A(DEN0024.pdf) (click to download)

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Attributes:

1.memory_type,

2.cacheability,

3.shareability,

4.access(R/W/E) permission.

Mem Type: Page 193

1.MT_NORMAL(NC)
including ROM RAM and Flash.
1)high performance
2)weakly ordered
3)fewer restrictions
4)addr_location access speculatively

NC: None Cacheable

2.MT_DEVICE_(N)G(N)R(N)
1)easy to have side-effect:(1)FIFO,timer read access not repeatable.(2)write access may trigger INTR
2)more restrictions
3)speculative data access not supported
4)execute unpredictable

G(ather) R(e-ordering) E(arly Write Acknoledgement)
(device is non-cacheable & outer-shareable by default)

PTE share and Cache Property: Page 179

PTE_BLOCK_NON_SHARE: memory accessible only by a single processor or other agent, never need to be synchronized
PTE_BLOCK_INNER_SHARE: shared by multiple processors, but not necessarily all of the agents in the system
PTE_BLOCK_OUTER_SHARE: shared by multiple agents

PTE_BLOCK_PXN/UXN: Page 201

PXN: Privileged Execute Never
UXN: UnPrivileged Execute Never

Picture of block memory attr: Page 201

Stage 1 block memory attributes (partly)
--- 54 53 ------------------10 9:8 7:6 5 4:2----
UXN PXN AF SH AP NS Indx

UXN/PXN: execution permissings
AF: access flag
SH: shareable
AP: access permissing
NS: (Non-)Secure
Indx: index into the Memory Attribute Indirection Register(MAIR_ELn)

Picture of Share model: Page 201