diff options
| author | Marvin Borner | 2020-07-28 22:00:26 +0200 |
|---|---|---|
| committer | Marvin Borner | 2020-07-28 22:00:26 +0200 |
| commit | 44fa7a529656c1ec8a445cac4ee7b40351a7c753 (patch) | |
| tree | a21dfcd91e2a2bc2913848bbd1bca264ce455d0e | |
| parent | 7786aca4ebabc78048ca2442b6734e99ba631872 (diff) | |
Make the bin smaller so direct pointers are enough
This is not a final sollution but will work for the moment. I'm just too
confused by assembly so I implemented some tricks to shrink the binary.
| -rw-r--r-- | Makefile | 4 | ||||
| -rw-r--r-- | src/entry.asm | 10 |
2 files changed, 9 insertions, 5 deletions
@@ -20,8 +20,10 @@ CC = cross/opt/bin/i686-elf-gcc LD = cross/opt/bin/i686-elf-ld AS = nasm +CSFLAGS = -fno-stack-protector -fomit-frame-pointer -ffunction-sections -fdata-sections -Wl,--gc-sections -mpreferred-stack-boundary=2 -falign-functions=1 -falign-jumps=1 -falign-loops=1 -fno-unwind-tables -fno-asynchronous-unwind-tables -fno-math-errno -fno-unroll-loops -fmerge-all-constants -fno-ident -ffast-math + # TODO: Use lib as external library -CFLAGS = -Wall -Wextra -nostdlib -nostdinc -ffreestanding -fno-builtin -fno-pic -mgeneral-regs-only -std=c99 -m32 -pedantic-errors -Isrc/lib/inc/ -Isrc/inc/ -c +CFLAGS = $(CSFLAGS) -Wall -Wextra -nostdlib -nostdinc -ffreestanding -fno-builtin -fno-pic -mgeneral-regs-only -std=c99 -m32 -pedantic-errors -Isrc/lib/inc/ -Isrc/inc/ -c ASFLAGS = -f elf32 diff --git a/src/entry.asm b/src/entry.asm index 4b8b247..5fdf4c2 100644 --- a/src/entry.asm +++ b/src/entry.asm @@ -311,8 +311,9 @@ kernel_load: xor ax, ax ; Clear ax mov dx, ax ; Clear dx - cmp cx, EXT2_DIRECT_POINTER_COUNT ; Indirect pointer needed? - jge .indirect ; Singly indirect pointer + ; TODO: Add singly pointer support (until ~12KiB) + ;cmp cx, EXT2_DIRECT_POINTER_COUNT ; Indirect pointer needed? + ;jge .indirect ; Singly indirect pointer mov ax, [di] ; Set ax = block pointer shl ax, 1 ; Multiply ax by 2 @@ -328,22 +329,23 @@ kernel_load: xor ebx, ebx + ; Read singly indirect pointer mov bx, EXT2_GET_ADDRESS(EXT2_KERNEL_INODE) ; First block lea di, [bx + EXT2_IND_POINTER_OFFSET] ; Address of singly indirect pointer mov bx, 0x3000 ; Arbitrary address - mov ax, [di] ; Set ax = block pointer shl ax, 1 ; Multiply ax by 2 mov [lba], ax mov [dest], bx call disk_read + ; Read data sub cx, EXT2_DIRECT_POINTER_COUNT lea di, [ebx + 4 * ecx] mov bx, 0x4000 ; Arbitrary address - mov ax, [di] shl ax, 1 + ;sub bx, 0x400 mov [lba], ax mov [dest], bx call disk_read |