diff options
Diffstat (limited to 'arch/i386/cpu/start16.S')
| -rw-r--r-- | arch/i386/cpu/start16.S | 29 |
1 files changed, 9 insertions, 20 deletions
diff --git a/arch/i386/cpu/start16.S b/arch/i386/cpu/start16.S index 1ebb6bc..3e8b2cc 100644 --- a/arch/i386/cpu/start16.S +++ b/arch/i386/cpu/start16.S @@ -44,11 +44,9 @@ board_init16_ret: movl %eax, %cr0 wbinvd - /* load the descriptor tables */ -o32 cs lidt idt_ptr + /* load the temporary Global Descriptor Table */ o32 cs lgdt gdt_ptr - /* Now, we enter protected mode */ movl %cr0, %eax orl $1,%eax @@ -57,6 +55,8 @@ o32 cs lgdt gdt_ptr /* Flush the prefetch queue */ jmp ff ff: + /* Tell 32-bit code it is being entered from hard-reset */ + movw $0x0001, %bx /* Finally jump to the 32bit initialization code */ movw $code32start, %ax @@ -68,12 +68,13 @@ code32start: .long _start /* offset */ .word 0x10 /* segment */ -idt_ptr: - .word 0 /* limit */ - .long 0 /* base */ - +/* + * The following Global Descriptor Table is just enough to get us into + * 'Flat Protected Mode' - It will be discarded as soon as the final + * GDT is setup in a safe location in RAM + */ gdt_ptr: - .word 0x30 /* limit (48 bytes = 6 GDT entries) */ + .word 0x20 /* limit (32 bytes = 4 GDT entries) */ .long BOOT_SEG + gdt /* base */ /* The GDT table ... @@ -83,8 +84,6 @@ gdt_ptr: * 0x08 Unused * 0x10 32bit code * 0x18 32bit data/stack - * 0x20 16bit code - * 0x28 16bit data/stack */ gdt: @@ -100,13 +99,3 @@ gdt: .word 0x0 /* base address = 0 */ .word 0x9300 /* data read/write */ .word 0x00CF /* granularity = 4096, 386 (+5th nibble of limit) */ - - .word 0xFFFF /* 64kb */ - .word 0 /* base address = 0 */ - .word 0x9b00 /* data read/write */ - .word 0x0010 /* granularity = 1 (+5th nibble of limit) */ - - .word 0xFFFF /* 64kb */ - .word 0 /* base address = 0 */ - .word 0x9300 /* data read/write */ - .word 0x0010 /* granularity = 1 (+5th nibble of limit) */ |