TMPR4951B datasheet(97/256 Pages) TOSHIBA

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Chapter 4 Memory Management System

4-15

64-bit Kernel Mode, Physical Spaces (xkphys)

In Kernel mode, when KX = 1 in the Status register and bits 63-62 of the 64-bit virtual address

are 102, one of the two unmapped xkphys address spaces are selected, either cached or uncached.

Accesses with address bits 58-36 not equal to 0 cause an address error.

References to this space are not mapped; the physical address selected is taken from bits 35-0 of

the virtual address.

Bits 61-59 of the virtual address specify the cacheability and coherency

attributes, as shown in Table 4.2.5.

Table 4.2.5 Cacheability and Coherency Attributes

Value(61-59)

Cacheability and Coherency Attributes

Starting Address

Cacheable, non-coherent, write-through, no write

allocate

0x8000 0000 0000 0000

Cacheable, non-coherent, write-through, no write

allocate

0x8800 0000 0000 0000

Uncached

0x9000 0000 0000 0000

Cacheable, non-coherent

0x9800 0000 0000 0000

4-7

Reserved

0xA000 0000 0000 0000

64-bit Kernel Mode, Kernel Space (xkseg)

In Kernel mode, when KX

= 1 in the Status register and bits 63-62 of the 64-bit virtual address

are 112, the address space selected is one of the following:

•

kernel virtual space, xkseg, the current kernel virtual space; the virtual address is extended

with the contents of the 8-bit ASID field to form a unique virtual address

•

one of the four 32-bit kernel compatibility spaces, as described in the next section.

64-bit Kernel Mode, Compatibility Spaces (ckseg1~0, cksseg, ckseg3)

In Kernel mode, when KX = 1 in the Status register, bits 63-62 of the 64-bit virtual address are

112, and bits 61-31 of the virtual address equal-1, the lower two bytes of address, as shown in

Figure 4.2.3, select one of the following 512 Mbytes compatibility spaces.

•

ckseg0.

This 64-bit virtual address space is an unmapped region, compatible with the 32-bit

address model kseg0. The K0 field of the Config register, described in this chapter,

controls cacheability and coherency.

•

ckseg1.

This 64-bit virtual address space is an unmapped and uncached region, compatible

with the 32-bit address model kseg1.

•

cksseg.

This 64-bit virtual address space is the current supervisor virtual space, compatible

with the 32-bit address model ksseg.

•

ckseg3.

This 64-bit virtual address space is kernel virtual space, compatible with the 32-bit

address model kseg3.

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