Compaq ECQD2KCTE manual 11-3

Table 11–2 : Privileged Windows NT Alpha PALcode Instruction Summary (Continued)

Mnemonic	Operation and description
draina	Drain all aborts including machine checks
	The draina instruction drains all aborts, including machine checks, from the
	current processor. Draina guarantees that no abort is signaled for an instruction
	issued before the draina while any instruction issued subsequent to the draina is
	executing.
dtbis	Data translation buffer invalidate single
	The dtbis instruction invalidates a single data stream translation. The transla-
	tion for the virtual address must be invalidated in all data translation buffers
	and in all virtual data caches.
ealnfix	Enable alignment fixups
	The ealnfix instruction enables alignment fixups in PALcode and prevents
	alignment fault exceptions. After ealnfix is executed on a processor, all align-
	ment faults on that processor are fixed-up by PALcode and no alignment fault
	exceptions are dispatched to the kernel until the dalnfix instruction is executed
	on that processor.
ei	Enable interrupts
	The ei instruction enables interrupts for the IRQL set in the PSR internal pro-
	cessor register by setting the interrupt enable (IE) bit in the PSR.
halt	Halt the operating system by forcing illegal instruction trap
	The halt instruction forces an illegal instruction exception.
initpal	Initialize PALcode data structures with operating system values
	The initpal instruction is called early in the kernel initialization sequence to
	establish values for internal processor registers (IPRs) that are needed for trap
	and fault handling. The KGP and PCR registers are initialized once and persist
	throughout the run time of the operating system.
initpcr	Initialize processor control region data
	The initpcr instruction caches process-specific information, including parts of
	the interrupt level table (ILT), for use by the PALcode.
rdcounters	Read the software event counters
	The rdcounters instruction is only used with debug PALcode. With production
	PALcode, rdcounters returns a status value of zero, indicating that it is not
	implemented in the current PALcode image.

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