Compaq ECQD2KCTE manual Privileged Windows NT Alpha PALcode

Table 11–1 : Unprivileged Windows NT Alpha PALcode Instruction Summary

Mnemonic	Operation and description
imb	Instruction memory barrier
	The imb instruction guarantees that all subsequent instruction stream fetches
	are coherent with respect to main memory. Imb must be issued before execut-
	ing code in memory that has been modified (either by stores from the processor
	or DMA from an I/O processor). User-mode code that modifies the I-stream
	must call the appropriate Windows NT API to ensure I-cache coherency.
kbpt	Kernel breakpoint trap
	The kbpt instruction raises a breakpoint general exception to the kernel, setting
	a KERNEL_BREAKPOINT breakpoint type.
rdteb	Read thread environment block pointer
	The rdteb instruction returns the contents of the TEB internal processor register
	for the currently executing thread (the base address of the thread environment
	block).

11.2 Privileged Windows NT Alpha PALcode

The privileged PALcode instuctions provide support for system operations and may be called from only kernel mode.

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

Mnemonic	Operation and description
csir	Clear software interrupt request
	The csir instruction clears the specified bit in the SIRR internal processor regis-
	ter.
dalnfix	Disable alignment fixups
	The dalnfix instruction disables alignment fixups in PALcode and generates
	alignment fault exceptions whenever an alignment fault occurs. After dalnfix is
	executed on a processor, all alignment faults on that processor are not fixed-up
	by PALcode and alignment fault exceptions are dispatched to the kernel until
	the ealnfix instruction is executed on that processor.
di	Disable all interrupts
	The di instruction disables all interrupts by clearing the interrupt enable (IE) bit
	in the PSR internal processor register. The IRQL field is unaffected. Interrupts
	may be re-enabled via the ei instruction.

11–2Alpha Architecture Handbook