Moved gdt_init in dt directory
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lucic71
parent
32f6426583
commit
393e8f79d8
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@ -1,12 +1,14 @@
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#include "i386/gdt.h"
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#include "i386/a20.h"
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.global _start
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/* Entry point in the kernel. */
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.extern kmain
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/* Symbols used to jump/return to/from gdt_init. */
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.extern gdt_init
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.global gdt_return
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/*
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* GRUB will load the kernel only if it compiles with the multiboot spec.
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* The header must contain a magic number, a flag (which can be set to 0x00)
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@ -21,10 +23,10 @@
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/*
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* Put the header in multiboot section so that it is placed in the first 8Kib
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* of the executable.
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*
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*/
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* Put the header in multiboot section so that it is placed in the first 8Kib
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* of the executable.
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*
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*/
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.section .multiboot
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.align 4
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@ -33,46 +35,6 @@
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.int FLAGS
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.int CHECKSUM
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/*
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* GDT (Global Descriptor Table) data needed to enter in protected mode. At
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* the moment it contains data and code segments for ring 0.
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*
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* CODE_PL0_SEL and DATA_PL0_SEL are used to fill the segment registers after
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* GDT was loaded. They are offsets from the beginning of GDT.
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*
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*/
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.data
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.align 4
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/* GDT pointer. */
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gdt_ptr:
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.short gdt_end - gdt_null - 1
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.int gdt_null
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/* GDT */
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gdt_null:
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.int 0
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.int 0
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gdt_code_pl0:
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.quad GDT_ENTRY(0, 0x000FFFFF, (GDT_CODE_PL0))
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gdt_data_pl0:
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.quad GDT_ENTRY(0, 0x000FFFFF, (GDT_DATA_PL0))
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gdt_end:
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.set CODE_PL0_SEL, gdt_code_pl0 - gdt_null
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.set DATA_PL0_SEL, gdt_data_pl0 - gdt_null
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/* Create a kstack so that the entry point in the kernel can be called. */
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.set KSTACK_SIZE, 4096
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@ -81,8 +43,6 @@
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.align 16
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kstack: .skip KSTACK_SIZE
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ljmp_addr: .skip 0x06
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/* Set up GDT and the stack, after that kmain can be called. */
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@ -91,79 +51,12 @@
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_start:
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disable_intrpt:
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/* Use a jmp instead of call because there is no valid stack. */
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cli
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jmp gdt_init
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prot_to_real:
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/* Switch to real mode to be able to execute lgdt. */
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mov %cr0, %eax
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and $~0x01, %eax
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mov %eax, %cr0
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enable_a20:
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/*
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* Read the value from I/O port FAST_A20_GATE, test to A20_ENABLED_BIT,
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* if the result is 0 then enable the A20 line and unset bit 0 because
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* we don't want to fast reset, else just skip this step.
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*
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* This is stil incomplete because the hardware may not support this kind
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* of enabling.
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*
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*/
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in $FAST_A20_GATE, %al
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test $A20_ENABLED_BIT, %al
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jnz .skip_a20
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or $A20_ENABLED_BIT, %al
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and $~FAST_RESET_MASK, %al
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out %al, $FAST_A20_GATE
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.skip_a20:
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gdt_init:
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/*
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* Zero ds register because we want to work with the physical address of
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* gdt_ptr rather than with its linear address. Load the gdt_ptr and enter
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* in protected mode to make the far jump and change the cs register.
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*
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*/
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xor %ax, %ax
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mov %ax, %ds
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lgdt gdt_ptr
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mov %cr0, %eax
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or $0x01, %eax
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mov %eax, %cr0
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jmp $CODE_PL0_SEL, $gdt_flush
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gdt_flush:
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/*
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* At this moment, cs has the value CODE_PL0_VALUE, we need to set the rest
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* of segment register. They will all have the same value,
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* namely DATA_PL0_SEL.
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*
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*/
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mov $DATA_PL0_SEL, %ax
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mov %ax, %ds
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mov %ax, %es
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mov %ax, %fs
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mov %ax, %gs
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mov %ax, %ss
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enable_intrpt:
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gdt_return:
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sti
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@ -176,6 +69,10 @@ stack_init:
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kentry:
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/* Set ebp to 0 to start the backtrace in kmain. */
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xor %ebp, %ebp
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/*
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* Now that we are in protected mode and the stack is set up we cann call
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* the kernel entry point.
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@ -0,0 +1,115 @@
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#include "i386/gdt.h"
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#include "i386/a20.h"
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.global gdt_init
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.extern gdt_return
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/*
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* GDT (Global Descriptor Table) data needed to enter in protected mode. At
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* the moment it contains data and code segments for ring 0.
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*
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* CODE_PL0_SEL and DATA_PL0_SEL are used to fill the segment registers after
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* GDT was loaded. They are offsets from the beginning of GDT.
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*
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*/
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.data
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.align 4
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/* GDT pointer. */
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gdt_ptr:
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.short gdt_end - gdt_null - 1
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.int gdt_null
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/* GDT */
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gdt_null:
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.int 0
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.int 0
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gdt_code_pl0:
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.quad GDT_ENTRY(0, 0x000FFFFF, (GDT_CODE_PL0))
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gdt_data_pl0:
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.quad GDT_ENTRY(0, 0x000FFFFF, (GDT_DATA_PL0))
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gdt_end:
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.set CODE_PL0_SEL, gdt_code_pl0 - gdt_null
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.set DATA_PL0_SEL, gdt_data_pl0 - gdt_null
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.text
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gdt_init:
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prot_to_real:
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/* Switch to real mode to be able to execute lgdt. */
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mov %cr0, %eax
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and $~0x01, %eax
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mov %eax, %cr0
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enable_a20:
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/*
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* Read the value from I/O port FAST_A20_GATE, test to A20_ENABLED_BIT,
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* if the result is 0 then enable the A20 line and unset bit 0 because
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* we don't want to fast reset, else just skip this step.
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*
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* This is stil incomplete because the hardware may not support this kind
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* of enabling.
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*
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*/
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in $FAST_A20_GATE, %al
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test $A20_ENABLED_BIT, %al
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jnz .skip_a20
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or $A20_ENABLED_BIT, %al
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and $~FAST_RESET_MASK, %al
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out %al, $FAST_A20_GATE
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.skip_a20:
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gdt_load:
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/*
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* Zero ds register because we want to work with the physical address of
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* gdt_ptr rather than with its linear address. Load the gdt_ptr and enter
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* in protected mode to make the far jump and change the cs register.
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*
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*/
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xor %ax, %ax
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mov %ax, %ds
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lgdt gdt_ptr
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mov %cr0, %eax
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or $0x01, %eax
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mov %eax, %cr0
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jmp $CODE_PL0_SEL, $gdt_flush
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gdt_flush:
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/*
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* At this moment, cs has the value CODE_PL0_VALUE, we need to set the rest
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* of segment register. They will all have the same value,
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* namely DATA_PL0_SEL.
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*
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*/
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mov $DATA_PL0_SEL, %ax
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mov %ax, %ds
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mov %ax, %es
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mov %ax, %fs
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mov %ax, %gs
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mov %ax, %ss
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jmp gdt_return
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@ -7,6 +7,7 @@ KERNEL_ARCH_OBJS=\
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$(ARCHDIR)/boot.o \
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$(ARCHDIR)/dt/idt.o \
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$(ARCHDIR)/dt/idt_flush.o \
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$(ARCHDIR)/dt/gdt.o \
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$(ARCHDIR)/isr/isr.o \
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$(ARCHDIR)/isr/isr_gate.o \
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$(ARCHDIR)/irq/pic.o \
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