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CHAPTER 2 V
R
4120A
Preliminary User’s Manual S14767EJ1V0UM00
139
(1) suseg (32-bit supervisor mode, user space)
When SX = 0 in the Status register and the most-significant bit of the virtual address space is set to 0, the suseg
virtual address space is selected; it covers 2 Gbytes (2
address is extended with the contents of the 8-bit ASID field to form a unique virtual address. This mapped space
starts at virtual address 0x0000 0000 and runs through 0x7FFF FFFF.
31
bytes) of the current user address space. The virtual
(2) sseg (32-bit supervisor mode, supervisor space)
When SX = 0 in the Status register and the most-significant three bits of the virtual address space are 110, the
sseg virtual address space is selected; it covers 512 Mbytes (2
space. The virtual address is extended with the contents of the 8-bit ASID field to form a unique virtual address.
This mapped space begins at virtual address 0xC000 0000 and runs through 0xDFFF FFFF.
29
bytes) of the current supervisor virtual address
(3) xsuseg (64-bit supervisor mode, user space)
When SX = 1 in the Status register and bits 63 and 62 of the virtual address space are set to 00, the xsuseg virtual
address space is selected; it covers 1 Tbyte (2
extended with the contents of the 8-bit ASID field to form a unique virtual address. This mapped space starts at
virtual address 0x0000 0000 0000 0000 and runs through 0x0000 00FF FFFF FFFF.
40
bytes) of the current user address space. The virtual address is
(4) xsseg (64-bit supervisor mode, current supervisor space)
When SX = 1 in the Status register and bits 63 and 62 of the virtual address space are set to 01, the xsseg virtual
address space is selected; it covers 1 Tbyte (2
address is extended with the contents of the 8-bit ASID field to form a unique virtual address. This mapped space
begins at virtual address 0x4000 0000 0000 0000 and runs through 0x4000 00FF FFFF FFFF.
40
bytes) of the current supervisor virtual address space. The virtual
(5) csseg (64-bit supervisor mode, separate supervisor space)
When SX = 1 in the Status register and bits 63 and 62 of the virtual address space are set to 11, the csseg virtual
address space is selected; it covers 512 Mbytes (2
virtual address is extended with the contents of the 8-bit ASID field to form a unique virtual address. This mapped
space begins at virtual address 0xFFFF FFFF C000 0000 and runs through 0xFFFF FFFF DFFF FFFF.
29
bytes) of the separate supervisor virtual address space. The
2.5.2.7 Kernel-mode virtual addressing
If the Status register satisfies any of the following conditions, the processor runs in Kernel mode.
—
KSU = 00
—
EXL = 1
—
ERL = 1
The addressing width in Kernel mode varies according to the state of the KX bit of the Status register, as follows:
—
When KX = 0:
—
When KX = 1:
32-bit kernel space is selected.
64-bit kernel space is selected.
The processor enters Kernel mode whenever an exception is detected and it remains in Kernel mode until an
exception return (ERET) instruction is executed and results in ERL and/or EXL = 0. The ERET instruction restores
the processor to the mode existing prior to the exception.