System Control
ARM DDI 0500D
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4-230
ID021414
Non-Confidential
Figure 4-116 TTBCR bit assignments, TTBCR.EAE is 1
Table 4-211
shows the TTBCR bit assignments when TTBCR.EAE is 1.
31 30 29 28 27 26 25 24 23 22 21
19 18
16 15 14 13 12 11 10 9 8 7 6
3 2
SH1
A1
T1SZ
SH0
RES
0
TDSZ
EAE
EPD0
0
RES
0
ORGN1
IRGN1
EPD1
IRGN0
ORGN0
RES
0
RES
0
Table 4-211 TTBCR bit assignments, TTBCR.EAE is 1
Bits
Name
Function
[31]
EAE
Extended Address Enable:
1
Use the 40-bit translation system, with the Long-descriptor translation table format.
[30]
-
Reserved,
RES
0.
[29:28]
SH1
Shareability attribute for memory associated with translation table walks using TTBR1:
0b00
Non-shareable.
0b10
Outer Shareable.
0b11
Inner Shareable.
Other values are reserved.
Resets to 0.
[27:26]
ORGN1
Outer cacheability attribute for memory associated with translation table walks using TTBR1:
0b00
Normal memory, Outer Non-cacheable.
0b01
Normal memory, Outer Write-Back Write-Allocate Cacheable.
0b10
Normal memory, Outer Write-Through Cacheable.
0b11
Normal memory, Outer Write-Back no Write-Allocate Cacheable.
Resets to 0.
[25:24]
IRGN1
Inner cacheability attribute for memory associated with translation table walks using TTBR1:
0b00
Normal memory, Inner Non-cacheable.
0b01
Normal memory, Inner Write-Back Write-Allocate Cacheable.
0b10
Normal memory, Inner Write-Through Cacheable.
0b11
Normal memory, Inner Write-Back no Write-Allocate Cacheable.
Resets to 0.
[23]
EPD1
Translation table walk disable for translations using TTBR1. This bit controls whether a translation table walk
is performed on a TLB miss, for an address that is translated using TTBR1:
0
Perform translation table walks using TTBR1.
1
A TLB miss on an address that is translated using TTBR1 generates a Translation fault. No
translation table walk is performed.