Read-only access to CPO registers

Details Read-only access to CPO registers Read-only access to CPO registers

2007-02-20

2007-02-20

Coleman, Eric (Department: 2183)

Electrical computers and digital processing systems: processing

Processing control

Mode switch or change

Reexamination Certificate

active

09921377

ABSTRACT:
A bit mask register is provided within the privileged architecture of a microprocessor. The bit mask register includes a plurality of bits, the bits corresponding to other privileged architecture registers. When a bit in the bit mask register is set, its corresponding privileged architecture register is made read-only accessible when the microprocessor is in user mode. When a bit in the bit mask register is clear, its corresponding privileged architecture register is unavailable when the microprocessor is in user mode. If an instruction executing in user mode requests access to a privileged architecture register, and its corresponding bit in the bit mask register is clear, an exception is generated, allowing a kernel mode operating system to optionally set the corresponding bit in the bit mask register, and provide read-only access to the register.

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