diff options
Diffstat (limited to 'arch/i386/kernel/head.S')
| -rw-r--r-- | arch/i386/kernel/head.S | 136 |
1 files changed, 67 insertions, 69 deletions
diff --git a/arch/i386/kernel/head.S b/arch/i386/kernel/head.S index 2bd095997..a42b87b1b 100644 --- a/arch/i386/kernel/head.S +++ b/arch/i386/kernel/head.S @@ -39,19 +39,21 @@ startup_32: jz 1f /* * New page tables may be in 4Mbyte page mode and may - * be using the global pages. + * be using the global pages. + * + * NOTE! We have to correct for the fact that we're + * not yet offset 0xC0000000.. */ +#define cr4_bits mmu_cr4_features-0xC0000000 #ifdef GAS_KNOWS_CR4 movl %cr4,%eax # Turn on 4Mb pages - orl $16+128,%eax + orl cr4_bits,%eax movl %eax,%cr4 #else .byte 0x0f,0x20,0xe0 - orl $16+128,%eax + orl cr4_bits,%eax .byte 0x0f,0x22,0xe0 #endif - movl %eax,%cr3 /* flush TLB as per app note */ - movl %cr0,%eax #endif /* * Setup paging (the tables are already set up, just switch them on) @@ -67,24 +69,16 @@ startup_32: movl $1f,%eax jmp *%eax /* make sure eip is relocated */ 1: + /* Set up the stack pointer */ + lss stack_start,%esp #ifdef __SMP__ orw %bx,%bx jz 1f /* Initial CPU cleans BSS */ -/* - * Set up the stack - */ - movl $(KERNEL_DS),%eax /* walken modif */ - mov %ax,%ss - xorl %eax,%eax - movw %cx, %ax - movl %eax,%esp - addl $0xC0000000, %esp /* shift it to the upper mapping */ pushl $0 popfl jmp checkCPUtype 1: - lss stack_start,%esp #endif __SMP__ /* * Clear BSS first so that there are no surprises... @@ -305,15 +299,53 @@ rp_sidt: jne rp_sidt ret +ENTRY(stack_start) + .long SYMBOL_NAME(init_task_union)+8192 + .long KERNEL_DS + +/* This is the default interrupt "handler" :-) */ +int_msg: + .asciz "Unknown interrupt\n" + ALIGN +ignore_int: + cld + pushl %eax + pushl %ecx + pushl %edx + push %ds + movl $(KERNEL_DS),%eax + mov %ax,%ds + mov %ax,%es + mov %ax,%fs + pushl $int_msg + call SYMBOL_NAME(printk) + popl %eax + pop %ds + popl %edx + popl %ecx + popl %eax + iret + +/* + * The interrupt descriptor table has room for 256 idt's + */ + ALIGN +.word 0 +idt_descr: + .word 256*8-1 # idt contains 256 entries + .long SYMBOL_NAME(idt) + + ALIGN +.word 0 +gdt_descr: +#ifdef CONFIG_APM + .word (11+2*NR_TASKS)*8-1 +#else + .word (8+2*NR_TASKS)*8-1 +#endif + .long SYMBOL_NAME(gdt) /* - * page 0 is made non-existent, so that kernel NULL pointer references get - * caught. Thus the swapper page directory has been moved to 0x101000 - * with the introduction of the compressed boot code. Theoretically, - * the original design of overlaying the startup code with the swapper - * page directory is still possible --- it would reduce the size of the kernel - * by 2-3k. This would be a good thing to do at some point..... - * * This is initialized to create a identity-mapping at 0-4M (for bootup * purposes) and another mapping of the 0-4M area at virtual address * 0xC0000000. @@ -471,63 +503,29 @@ ENTRY(empty_bad_page_table) ENTRY(empty_zero_page) .org 0x6000 - -stack_start: - .long SYMBOL_NAME(init_user_stack)+4096 - .long KERNEL_DS - -/* This is the default interrupt "handler" :-) */ -int_msg: - .asciz "Unknown interrupt\n" - ALIGN -ignore_int: - cld - pushl %eax - pushl %ecx - pushl %edx - push %ds - push %es - push %fs - movl $(KERNEL_DS),%eax - mov %ax,%ds - mov %ax,%es - mov %ax,%fs - pushl $int_msg - call SYMBOL_NAME(printk) - popl %eax - pop %fs - pop %es - pop %ds - popl %edx - popl %ecx - popl %eax - iret +ENTRY(this_must_match_init_task) /* - * The interrupt descriptor table has room for 256 idt's + * This starts the data section. Note that the above is all + * in the text section because it has alignment requirements + * that we cannot fulfill any other way. */ - ALIGN -.word 0 -idt_descr: - .word 256*8-1 # idt contains 256 entries - .long SYMBOL_NAME(idt) +.data +ALIGN +/* 256 quadwords - 2048 bytes of idt */ ENTRY(idt) .fill 256,8,0 # idt is uninitialized - ALIGN -.word 0 -gdt_descr: -#ifdef CONFIG_APM - .word (11+2*NR_TASKS)*8-1 -#else - .word (8+2*NR_TASKS)*8-1 -#endif - .long SYMBOL_NAME(gdt) - /* * This gdt setup gives the kernel a 1GB address space at virtual * address 0xC0000000 - space enough for expansion, I hope. + * + * This contains up to 8192 quadwords depending on NR_TASKS - 64kB of + * gdt entries. Ugh. + * + * NOTE! Make sure the gdt descriptor in head.S matches this if you + * change anything. */ ENTRY(gdt) .quad 0x0000000000000000 /* NULL descriptor */ |