diff options
Diffstat (limited to 'kernel/startup.S')
| -rw-r--r-- | kernel/startup.S | 161 |
1 files changed, 0 insertions, 161 deletions
diff --git a/kernel/startup.S b/kernel/startup.S deleted file mode 100644 index 94b93b0..0000000 --- a/kernel/startup.S +++ /dev/null @@ -1,161 +0,0 @@ -/* -** @file startup.S -** -** @author Jon Coles -** @authors Warren R. Carithers, K. Reek -** -** SP startup code. -** -** This code prepares the various registers for execution of -** the program. It sets up all the segment registers and the -** runtime stack. By the time this code is running, we're in -** protected mode already. -*/ - -#define KERNEL_SRC -#define ASM_SRC - -# .arch i386 - -#include <common.h> -#include <bootstrap.h> -#include <x86/arch.h> -#include <x86/bios.h> -#include <vm.h> - -/* -** Configuration options - define in Makefile -** -** CLEAR_BSS include code to clear all BSS space -** OS_CONFIG OS-related (vs. just standalone) variations -*/ - -/* -** A symbol for locating the beginning of the code. -*/ - .text - - .globl begtext - .globl _start -_start = V2PNC(begtext) - -/* -** The entry point. When we get here, we have just entered protected -** mode, so all the segment registers are incorrect except for CS. -*/ -begtext: - - cli /* seems to be reset on entry to p. mode */ - movb $NMI_ENABLE, %al /* re-enable NMIs (bootstrap */ - outb $CMOS_ADDR /* turned them off) */ - -/* -** Set the data and stack segment registers (code segment register -** was set by the long jump that switched us into protected mode). -*/ - xorl %eax, %eax /* clear EAX */ - movw $GDT_DATA, %ax /* GDT entry #3 - data segment */ - movw %ax, %ds /* for all four data segment registers */ - movw %ax, %es - movw %ax, %fs - movw %ax, %gs - - movw $GDT_STACK, %ax /* entry #4 is the stack segment */ - movw %ax, %ss - - movl $TARGET_STACK, %esp /* set up the system stack pointer */ - -#ifdef CLEAR_BSS -/* -** Zero the BSS segment -** -** These symbols are defined automatically by the linker, but they're -** defined at their virtual addresses rather than their physical addresses, -** and we haven't enabled paging yet. -*/ - .globl __bss_start, _end - - movl $V2PNC(__bss_start), %edi -clearbss: - movl $0, (%edi) - addl $4, %edi - cmpl $V2PNC(_end), %edi - jb clearbss -#endif /* CLEAR_BSS */ - -/* -** Enable paging. We use "large" pages for the initial page directory -** so that a one-level hierarchy will work for us. Once we have set -** up our memory freelist, we'll create a two-level hierarchy using -** "normal" 4KB pages. -*/ - # enable large pages - movl %cr4, %eax - orl $(CR4_PSE), %eax - movl %eax, %cr4 - - # set the page directory - .globl firstpdir - movl $(V2PNC(firstpdir)), %eax - movl %eax, %cr3 - - # turn on paging - movl %cr0, %eax - orl $(CR0_PG), %eax - movl %eax, %cr0 - - # reset our stack pointer - movl $(kstack + SZ_KSTACK), %esp - - # set the initial frame pointer - xorl %ebp, %ebp - - # now, jump and switch into using high addresses - # we use an indirect jump here because the assembler - # would ordinarily generate a PC-relative target - # address for the jump, which would not have the - # desired effect - movl $onward, %eax - jmp *%eax - -onward: - -/* -** Call the system initialization routine. -** -** Alternate idea: push the address of isr_restore -** and just do an indirect jump? -*/ - .globl main - - movl $main, %eax - call *%eax - -/* -** At this point, main() must have created the first user -** process, and we're ready to shift into user mode. The user -** stack for that process must have the initial context in it; -** we treat this as a "return from interrupt" event, and just -** transfer to the code that restores the user context. -*/ - - .globl isr_restore - jmp isr_restore - - .data - -/* -** Define the kernel stack here, at a multiple-of-16 address -*/ - .p2align 4 - .globl kstack -kstack: .space SZ_KSTACK, 0 - -/* -** Define the initial kernel ESP here, as well. It should point -** to the first byte after the stack. -*/ - - .globl kernel_esp -kernel_esp: - .long kstack + SZ_KSTACK |