a simple boot loader that will be copied to all disks that outputs a message

telling the user that the machine requires a boot cd

diff --git a/dummy_bootloader/Makefile b/dummy_bootloader/Makefile
new file mode 100644 (file)
index 0000000..6268133
--- /dev/null
+++ b/dummy_bootloader/Makefile
@@ -0,0 +1,17 @@
+all: dummy_bootloader
+
+dummy_bootloader: dummy_bootloader.S
+       nasm $< -o $@
+
+testbootdisk: dummy_bootloader
+       $(shell dd if=/dev/zero of=testbootdisk bs=512 count=2880)
+
+run: testbootdisk
+       $(shell dd if=dummy_bootloader of=testbootdisk conv=notrunc)
+       $(shell qemu -fda testbootdisk -boot a)
+
+clean:
+       rm -f dummy_bootloader
+       rm -f testbootdisk
+
+.phony: all run clean

diff --git a/dummy_bootloader/dummy_bootloader.S b/dummy_bootloader/dummy_bootloader.S
new file mode 100644 (file)
index 0000000..c8f1512
--- /dev/null
+++ b/dummy_bootloader/dummy_bootloader.S
@@ -0,0 +1,44 @@
+SCREEN_COLS     equ 80
+SCREEN_ROWS     equ 25
+STACK_SEGMENT   equ 09000h     ; top of memory
+STACK_SIZE      equ 00fffh     ; 4K - 1 bytes of stack
+       
+TEXT_COLOR     equ 0x07        ; white on black
+
+       jmp 07c0h:start
+
+message                db "PlanetLab nodes require a boot cd at all times to function.",0
+       
+start:
+       mov ax, cs
+       mov ds, ax
+       mov es, ax
+       
+       mov sp, STACK_SEGMENT   ; setup stack (not really used)
+       mov ss, sp
+       mov sp, STACK_SIZE
+
+       ;; clear out the screen, using the scroll down bios int.
+       mov ah, 0x07            ; for int 0x10, 0x07 is scroll down window
+       mov al, 0               ; entire window
+       mov cx, 0               ; upper left corner = (0,0)
+       mov dh, SCREEN_ROWS     ; row of bottom
+       mov dl, SCREEN_COLS     ; column of right
+       mov bh, 7
+       int 10h                 
+       
+       mov si, message
+
+strout: lodsb
+       cmp al, 0
+       je done
+       mov ah, 0x0E            ; for int 0x10, 0xOE is char out
+       mov bx, TEXT_COLOR
+       int 0x10
+       jmp strout
+
+done:  
+       jmp done
+       
+       times 510 - ($ - $$) db 0 ;  last two bytes are magic for x86 boot sectors
+       dw 0aa55h