diff options
Diffstat (limited to 'apps/bos/switch_to_pm.asm')
| -rw-r--r-- | apps/bos/switch_to_pm.asm | 34 |
1 files changed, 0 insertions, 34 deletions
diff --git a/apps/bos/switch_to_pm.asm b/apps/bos/switch_to_pm.asm deleted file mode 100644 index aeef97c0..00000000 --- a/apps/bos/switch_to_pm.asm +++ /dev/null @@ -1,34 +0,0 @@ -[bits 16] -; Switch to protected mode -switch_to_pm: - cli ; We must switch of interrupts until we have - ; set up the protected mode interrupt vector - ; otherwise interrupts will run riot. - - lgdt [gdt_descriptor] ; Load our global descriptor table, which defines - ; the protected mode segments (e.g. for code and data) - - mov eax, cr0 ; To make the switch to protected mode, we set - or eax, 0x1 ; the first bit of CR0, a control register - mov cr0, eax - - jmp CODE_SEG:init_pm ; Make a far jump (i.e. to a new segment) to our 32-bit - ; code. This also forces the CPU to flush its cache of - ; prefetched and real-mode decoded instructions, which can - ; cause problems. - -[bits 32] -; Initialise registers and the stack once in PM. -init_pm: - - mov ax, DATA_SEG ; Now in PM, our old segments are meaningless, - mov ds, ax ; so we point our segment registers to the - mov ss, ax ; data selector we defined in our GDT - mov es, ax - mov fs, ax - mov gs, ax - - mov ebp, 0x90000 ; Update our stack position so it is right - mov esp, ebp ; at the top of the free space. - - call BEGIN_PM ; Finally, call some well-known label |