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| author | Russ Cox <rsc@swtch.com> | 2009-07-11 19:15:32 -0700 |
|---|---|---|
| committer | Russ Cox <rsc@swtch.com> | 2009-07-11 19:15:32 -0700 |
| commit | 887f19686cf377db55953dac651ca8147c268092 (patch) | |
| tree | 4657092bb085b53a043e2af0f885ba6d3c880b71 | |
| parent | 8b75366ce4ae7ad5f77225b247d097955574ba0b (diff) | |
| download | xv6-labs-887f19686cf377db55953dac651ca8147c268092.tar.gz xv6-labs-887f19686cf377db55953dac651ca8147c268092.tar.bz2 xv6-labs-887f19686cf377db55953dac651ca8147c268092.zip | |
bootasm cleanup
| -rw-r--r-- | bootasm.S | 3 | ||||
| -rw-r--r-- | bootother.S | 21 |
2 files changed, 12 insertions, 12 deletions
@@ -86,8 +86,7 @@ gdt: SEG_NULLASM # null seg SEG_ASM(STA_X|STA_R, 0x0, 0xffffffff) # code seg SEG_ASM(STA_W, 0x0, 0xffffffff) # data seg - SEG_ASM(STA_W, 0x100, 0xffffffff) # per-cpu data seg; 0x100 is okay for now gdtdesc: - .word 0x1f # sizeof(gdt) - 1 + .word (gdtdesc - gdt - 1) # sizeof(gdt) - 1 .long gdt # address gdt diff --git a/bootother.S b/bootother.S index cb3ff4c..47f547e 100644 --- a/bootother.S +++ b/bootother.S @@ -19,15 +19,15 @@ # - it uses the address at start-4 for the %esp # - it jumps to the address at start-8 instead of calling bootmain -.set PROT_MODE_CSEG, 0x8 # kernel code segment selector -.set PROT_MODE_DSEG, 0x10 # kernel data segment selector -.set CR0_PE_ON, 0x1 # protected mode enable flag +#define SEG_KCODE 1 // kernel code +#define SEG_KDATA 2 // kernel data+stack +#define CR0_PE 1 // protected mode enable bit + +.code16 # Assemble for 16-bit mode .globl start start: - .code16 # Assemble for 16-bit mode cli # Disable interrupts - cld # String operations increment # Set up the important data segment registers (DS, ES, SS). xorw %ax,%ax # Segment number zero @@ -42,22 +42,23 @@ start: # effective memory map does not change during the switch. lgdt gdtdesc movl %cr0, %eax - orl $CR0_PE_ON, %eax + orl $CR0_PE, %eax movl %eax, %cr0 # Jump to next instruction, but in 32-bit code segment. # Switches processor into 32-bit mode. - ljmp $PROT_MODE_CSEG, $protcseg + ljmp $(SEG_KCODE<<3), $protcseg .code32 # Assemble for 32-bit mode protcseg: # Set up the protected-mode data segment registers - movw $PROT_MODE_DSEG, %ax # Our data segment selector + movw $(SEG_KDATA<<3), %ax # Our data segment selector movw %ax, %ds # -> DS: Data Segment movw %ax, %es # -> ES: Extra Segment + movw %ax, %ss # -> SS: Stack Segment + movw $0, %ax # Zero segments not ready for use movw %ax, %fs # -> FS movw %ax, %gs # -> GS - movw %ax, %ss # -> SS: Stack Segment movl start-4, %esp movl start-8, %eax @@ -81,5 +82,5 @@ gdt: SEG_ASM(STA_W, 0x0, 0xffffffff) # data seg gdtdesc: - .word 0x17 # sizeof(gdt) - 1 + .word (gdtdesc - gdt - 1) # sizeof(gdt) - 1 .long gdt # address gdt |