Compaq ECQD2KCTE manual 10-3

Table 10–2 : Privileged Digital UNIX PALcode Instruction Summary (Continued)

Mnemonic	Operation and Description
retsys	Return from system call The retsys instruction pops the return address, the user
	stack pointer, and the user global pointer from the kernel stack. It then saves the
	kernel stack pointer, sets mode to user, enables interrupts, and jumps to the
	address popped off the stack.
rti	Return from trap, fault or interrupt The rti instruction pops certain registers
	from the kernel stack. If the new mode is user, the kernel stack is saved and the
	user stack restored.
swpctx	Swap privileged context The swpctx instruction saves the current process data
	in the current process control block (PCB). Then swpctx switches to the PCB
	and loads the new process context.
swpipl	Swap IPL The swpipl instruction returns the current value IPL and sets the IPL.
swppal	Swap PALcode image The swppal instruction causes the current PALcode to
	be replaced by the specified new PALcode image. Intended only for use by
	operating systems during bootstraps and by consoles during transitions to con-
	sole I/O mode.
tbi	TB invalidate The tbi instruction removes entries from the instruction and data
	translation buffers when the mapping entries change.
whami	Who_Am_I The whami instruction returns the processor number for the cur-
	rent processor. The processor number is in the range 0 to the number of proces-
	sors minus one (0..numproc–1) that can be configured in the system.
wrent	Write system entry address The wrent instruction sets the virtual address of the
	system entry points.
wrfen	Write floating-point enable The wrfen instruction writes a bit to the floating-
	point enable register.
wripir	Write interprocessor interrupt request The wripr instruction generates an inter-
	processor interrupt on the processor number passed as an input parameter. The
	interrupt request is recorded on the target processor and initiated when the
	proper enabling conditions are present.
wrkgp	Write kernel global pointer The wrkgp instruction writes the kernel global
	pointer internal register.
wrmces	Write machine check error summary The wrmces instructions clears the
	machine check in progress bit and clears the processor- or system-correctable
	error in progress bit in the MCES register. The instruction also sets or clears the
	processor- or system-correctable error reporting enable bit in the MCES regis-
	ter.
wrperfmon	Performance monitoring function The wrperfmon instruction alerts any perfor-
	mance monitoring software/hardware in the system to monitor the performance
	of this process.
wrusp	Write user stack pointer The wrusp instruction writes a value to the user stack
	pointer while in kernel mode.

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