X86EnablePaging32.c File Reference

#include "BaseLibInternals.h"

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Functions
VOID EFIAPI	AsmEnablePaging32 (IN SWITCH_STACK_ENTRY_POINT EntryPoint, IN VOID *Context1 OPTIONAL, IN VOID *Context2 OPTIONAL, IN VOID *NewStack)

Detailed Description

IA-32/x64 AsmEnablePaging32()

Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.
SPDX-License-Identifier: BSD-2-Clause-Patent

Definition in file X86EnablePaging32.c.

Function Documentation

AsmEnablePaging32()

VOID EFIAPI AsmEnablePaging32	(	IN SWITCH_STACK_ENTRY_POINT	EntryPoint,
		IN VOID *Context1	OPTIONAL,
		IN VOID *Context2	OPTIONAL,
		IN VOID *	NewStack
	)

Enables the 32-bit paging mode on the CPU.

Enables the 32-bit paging mode on the CPU. CR0, CR3, CR4, and the page tables must be properly initialized prior to calling this service. This function assumes the current execution mode is 32-bit protected mode. This function is only available on IA-32. After the 32-bit paging mode is enabled, control is transferred to the function specified by EntryPoint using the new stack specified by NewStack and passing in the parameters specified by Context1 and Context2. Context1 and Context2 are optional and may be NULL. The function EntryPoint must never return.

If the current execution mode is not 32-bit protected mode, then ASSERT(). If EntryPoint is NULL, then ASSERT(). If NewStack is NULL, then ASSERT().

There are a number of constraints that must be followed before calling this function: 1) Interrupts must be disabled. 2) The caller must be in 32-bit protected mode with flat descriptors. This means all descriptors must have a base of 0 and a limit of 4GB. 3) CR0 and CR4 must be compatible with 32-bit protected mode with flat descriptors. 4) CR3 must point to valid page tables that will be used once the transition is complete, and those page tables must guarantee that the pages for this function and the stack are identity mapped.

Parameters

EntryPoint	A pointer to function to call with the new stack after paging is enabled.
Context1	A pointer to the context to pass into the EntryPoint function as the first parameter after paging is enabled.
Context2	A pointer to the context to pass into the EntryPoint function as the second parameter after paging is enabled.
NewStack	A pointer to the new stack to use for the EntryPoint function after paging is enabled.

Definition at line 50 of file X86EnablePaging32.c.