arch/x86/realmode/rm/trampoline_32.S

Source file repositories/reference/linux-study-clean/arch/x86/realmode/rm/trampoline_32.S

File Facts

System
Linux kernel
Corpus path
arch/x86/realmode/rm/trampoline_32.S
Extension
.S
Size
1919 bytes
Lines
74
Domain
Architecture Layer
Bucket
arch/x86
Inferred role
Architecture Layer: arch/x86
Status
atlas-only

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#include <linux/linkage.h>
#include <asm/segment.h>
#include <asm/page_types.h>
#include "realmode.h"

	.text
	.code16

	.balign	PAGE_SIZE
SYM_CODE_START(trampoline_start)
	wbinvd			# Needed for NUMA-Q should be harmless for others

	LJMPW_RM(1f)
1:
	mov	%cs, %ax	# Code and data in the same place
	mov	%ax, %ds

	cli			# We should be safe anyway

	movl	tr_start, %eax	# where we need to go

	/*
	 * GDT tables in non default location kernel can be beyond 16MB and
	 * lgdt will not be able to load the address as in real mode default
	 * operand size is 16bit. Use lgdtl instead to force operand size
	 * to 32 bit.
	 */
	lidtl	tr_idt			# load idt with 0, 0
	lgdtl	tr_gdt			# load gdt with whatever is appropriate

	movw	$1, %dx			# protected mode (PE) bit
	lmsw	%dx			# into protected mode

	ljmpl	$__BOOT_CS, $pa_startup_32
SYM_CODE_END(trampoline_start)

	.section ".text32","ax"
	.code32
SYM_CODE_START(startup_32)			# note: also used from wakeup_asm.S
	jmp	*%eax
SYM_CODE_END(startup_32)

	.bss
	.balign 8
SYM_DATA_START(trampoline_header)
	SYM_DATA_LOCAL(tr_start,	.space 4)
	SYM_DATA_LOCAL(tr_gdt_pad,	.space 2)
	SYM_DATA_LOCAL(tr_gdt,		.space 6)
SYM_DATA_END(trampoline_header)
	
#include "trampoline_common.S"

Annotation

Implementation Notes