acpi: calibrate local APIC timer on BSP

arch/x86_64/acpi/ap_trampoline.S

@@ -1,4 +1,3 @@
-
 	.global acpi_bsp_lapic_id
 	.type acpi_bsp_lapic_id, @function
 
@@ -18,11 +17,66 @@ acpi_bsp_lapic_id:
 	pop %rbp
 	ret
 
-	.global ap_trampoline
-	.type ap_trampoline, @function
-	.code16
 
-ap_trampoline:
-	mov $0xFF, %ax
+	.extern __ap_stack_top
+	.extern __bsp_done
+
+	.extern ap_startup
+	.type ap_startup, @function
+
+	.global ap_trampoline_code
+
+	# this code will be relocated to 0x8000, sets up environment for calling a C function
+	.code16
+ap_trampoline_code:
 	cli
+	cld
+	ljmp    $0, $0x8040
+	.align 16
+_L8010_GDT_table:
+	.long 0, 0
+	.long 0x0000FFFF, 0x00CF9A00    # flat code
+	.long 0x0000FFFF, 0x008F9200    # flat data
+	.long 0x00000068, 0x00CF8900    # tss
+_L8030_GDT_value:
+	.word _L8030_GDT_value - _L8010_GDT_table - 1
+	.long 0x8010
+	.long 0, 0
+	.align 64
+_L8040:
+	xorw    %ax, %ax
+	movw    %ax, %ds
+	lgdtl   0x8030
+	movl    %cr0, %eax
+	orl     $1, %eax
+	movl    %eax, %cr0
+	ljmp    $8, $0x8060
+
+	.align 32
+	.code32
+_L8060:
+	movw    $16, %ax
+	movw    %ax, %ds
+	movw    %ax, %ss
+	# get our Local APIC ID
+	mov     $1, %eax
+	cpuid
+	shrl    $24, %ebx
+	movl    %ebx, %edi
+
+	movl    $0x9000, %eax
+	movl    (%eax), %eax
+	mov     %eax, %cr3
 	hlt
+	# set up 32k stack, one for each core. It is important that all core must have its own stack
+	#shll    $15, %ebx
+	#movl    __ap_stack_top, %esp
+	#subl    %ebx, %esp
+	#pushl   %edi
+	# spinlock, wait for the BSP to finish
+#1:  	pause
+	#cmpb    $0, __bsp_done
+	#jz      1b
+	#lock    incb aprunning
+	# jump into C code (should never return)
+	#ljmp    $8, $ap_startup