Compaq ECQD2KCTE manual Unprivileged Windows NT Alpha PALcode

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Chapter 11

Windows NT Alpha

The following sections specify the Privileged Architecture Library (PALcode) instructions that are required to support a Windows NT Alpha system.

11.1 Unprivileged Windows NT Alpha PALcode

The unprivileged PALcode instuctions provide support for system operations and may be called from both kernel and user modes.

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

Mnemonic

Operation and description

bpt

Breakpoint trap (standard user-mode breakpoint)

 

The bpt instruction raises a breakpoint general exception to the kernel, setting a

 

USER_BREAKPOINT breakpoint type.

callkd

Call kernel debugger

 

The callkd instruction raises a breakpoint general exception to the kernel, set-

 

ting the breakpoint type with the value supplied as an input parameter.

callsys

System service call

 

The callsys instruction raises a system service call exception to the kernel. Call-

 

sys switches to kernel mode if necessary, builds a trap frame on the kernel

 

stack, and then enters the kernel at the kernel system service exception handler.

gentrap

Generate a trap

 

The gentrap instruction generates a software general exception that raises an

 

exception code to the current thread. The exception code is generated from a

 

trap number that is specified as an input parameter. Gentrap is used to raise

 

software-detected exceptions such as bound check errors or overflow condi-

 

tions.

 

 

11–1

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Compaq ECQD2KCTE manual Unprivileged Windows NT Alpha PALcode Instruction Summary