diff options
Diffstat (limited to 'boot/startup-x86_64.s')
| -rw-r--r-- | boot/startup-x86_64.s | 22 |
1 files changed, 8 insertions, 14 deletions
diff --git a/boot/startup-x86_64.s b/boot/startup-x86_64.s index 4f34cc7..4855bf0 100644 --- a/boot/startup-x86_64.s +++ b/boot/startup-x86_64.s @@ -26,17 +26,16 @@ MAX_MEM: equ 512 [BITS 32] startup: - cld ; GCC-compiled code expects the direction flag to be 0 - cli ; disable interrupts + cld + cli lgdt [gdt_80] ; set new segment descriptors ; global data segment mov eax, 3 * 0x8 - ; 0x8 is the length of each entry - ; these registers point to 4th entry the GDT (see also the code there) - ; in x86 long mode these are dummy pointers - ; which are not actually used in addressing. (don't use segmentation at all) - ; all the addresses are physical addresses from 0. + ; 0x8 is the length of each entry these registers point to 4th entry the GDT + ; (see also the code there) in x86 long mode these are dummy pointers which + ; are not actually used in addressing. (don't use segmentation at all) all + ; the addresses are physical addresses from 0. mov ds, ax mov es, ax mov fs, ax @@ -46,19 +45,16 @@ startup: mov ss, ax mov esp, init_stack+STACKSIZE -; -; Switch to 64-bit Long Mode -; - init_longmode: ; activate address extension (PAE) mov eax, cr4 or eax, 1 << 5 mov cr4, eax +setup_paging: ; Provisional identical page mapping, using 1G huge page (therefore only 2 table ; levels needed) -setup_paging: + ; ; PML4 (Page Map Level 4 / 1st level) mov eax, pdp or eax, 0xf @@ -96,7 +92,6 @@ activate_long_mode: ; jump to 64-bit code segment -> full activation of Long Mode jmp 2 * 0x8 : longmode_start - ; ; system start, part 2 (in 64-bit Long Mode) ; 1. clear BSS @@ -105,7 +100,6 @@ activate_long_mode: ; 4. (optional) enable SSE ; 5. jump to rust main code ; - longmode_start: [BITS 64] ; clear BSS |