msgclr

Message Clear

msgclr RB

Clears a pending doorbell interrupt (Inter-processor comms).

Encoding

Binary Layout

31

0:5

/

6:10

/

11:15

RB

16:20

118

21:30

/

31

 

Format X-form

Opcode 0x7C0001DC

Extension Privileged

Operands

• RB
  Message Type

Example

msgclr r5

Related

More in Privileged

Reference

View in PowerISA v3.1C Specification ↗ OPF Power ISA v3.1C

Description

Clears a pending doorbell or message interrupt from another processor, based on the message type specified in RB. This is a privileged instruction used for inter-processor communication and does not affect condition registers.

Operation

clear_pending_message(RB[62:63])

Programming Note

Use msgclr to clear messages accepted by the current thread. If clearing a message of type 0x05, it also clears any associated Directed Ultravisor Doorbell exception. This instruction is typically used in hypervisor environments where message handling and doorbell management are required.