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Datasheet, Volume 2
15
Processor Configuration Registers
2
Processor Configuration
Registers
This chapter contains the following:
• Register terminology
• PCI Devices and Functions on processor
• System address map
• Processor register introduction
• Detailed register bit descriptions
• PCI Devices and Functions on processor
• System address map
• Processor register introduction
• Detailed register bit descriptions
2.1
Register Terminology
lists the register-related terminology and access attributes that are used in
Table 2-1.
Register Attributes and Terminology
Item
Description
RO
Read Only: These bits can only be read by software, writes have no effect. The value of the bits is
determined by the hardware only.
RW
Read / Write: These bits can be read and written by software.
RW1C
Read / Write 1 to Clear: These bits can be read and cleared by software. Writing a '1' to a bit will
clear it, while writing a '0' to a bit has no effect. Hardware sets these bits.
RW0C
Read / Write 0 to Clear: These bits can be read and cleared by software. Writing a ‘0’ to a bit will
clear it, while writing a ‘1’ to a bit has no effect. Hardware sets these bits.
RW1S
Read / Write 1 to Set: These bits can be read and set by software. Writing a ‘1’ to a bit will set it,
while writing a ‘0’ to a bit has no effect. Hardware clears these bits.
RsvdP
Reserved and Preserved: These bits are reserved for future RW implementations and their value
must not be modified by software. When writing to these bits, software must preserve the value
read. When software updates a register that has RsvdP fields, it must read the register value first so
that the appropriate merge between the RsvdP and updated fields will occur.
RsvdZ
Reserved and Zero: These bits are reserved for future RW1C implementations. Software must use
0 for writes.
WO
Write Only: These bits can only be written by software, reads return zero.
Note:
Use of this attribute type is deprecated and can only be used to describe bits without
persistent state.
RC
Read Clear: These bits can only be read by software, but a read causes the bits to be cleared.
Hardware sets these bits.
Note:
Use of this attribute type is only allowed on legacy functions, as side-effects on reads are
not desirable.
RSW1C
Read Set / Write 1 to Clear: These bits can be read and cleared by software. Reading a bit will
set the bit to ‘1’. Writing a ‘1’ to a bit will clear it, while writing a ‘0’ to a bit has no effect.
RCW
Read Clear / Write: These bits can be read and written by software, but a read causes the bits to
be cleared.
Note:
Use of this attribute type is only allowed on legacy functions, as side-effects on reads are
not desirable.