big-img, chainload self

.gitignore

@@ -5,3 +5,4 @@
 *.iso
 *.o
 *.so
+*.tmp

Makefile

@@ -8,6 +8,7 @@ MYAS ?= gcc
 OBJ_EXT ?= .o
 OUT_EXT ?= .img
 RUN ?= bios_hello_world
+TMP_EXT ?= .tmp
 
 INS := $(wildcard *$(IN_EXT))
 OUTS := $(patsubst %$(IN_EXT),%$(OUT_EXT),$(INS))
@@ -24,7 +25,24 @@ all: $(OUTS)
 	$(MYAS) -c -o '$@' '$<'
 
 clean:
-	rm -f *$(OBJ_EXT) *$(OUT_EXT)
+	rm -fr *$(OBJ_EXT) *$(OUT_EXT) *$(TMP_EXT)
 
 run: all
 	qemu-system-i386 '$(RUN)$(OUT_EXT)'
+
+BIG_IMG_DIR := big_img$(TMP_EXT)
+BOOT_DIR := $(BIG_IMG_DIR)/boot
+GRUB_DIR := $(BOOT_DIR)/grub
+big-img: all
+	rm -rf '$(BIG_IMG_DIR)'
+	mkdir -p  '$(GRUB_DIR)'
+	for out in $(OUTS); do\
+	  printf "menuentry \"$${out%.*}\"  {\n   chainloader /boot/$$out\n}\n" >> '$(GRUB_DIR)/grub.cfg';\
+	  cp "$$out" '$(BOOT_DIR)';\
+	done
+	# TODO why does this fail to boot properly?
+	#make -C multiboot/hello-world
+	#mkdir -p '$(BOOT_DIR)/multiboot'
+	#printf "menuentry \"multiboot/hello-world\"  {\n   chainloader /boot/multiboot/hello-world.img\n}\n" >> '$(GRUB_DIR)/grub.cfg';\
+	#cp multiboot/hello-world/main.img '$(BOOT_DIR)/multiboot/hello-world.img'
+	grub-mkrescue -o 'big.img' '$(BIG_IMG_DIR)'

README.md

@@ -10,6 +10,9 @@ Hello world programs that run without an operating system.
     1.  BIOS
         1.  [BIOS one char](bios_one_char.S)
         1.  [BIOS hello world](bios_hello_world.S)
+        1.  [BIOS newline](bios_newline.S)
+        1.  [BIOS carriage return](bios_carriage_return.S)
+        1.  [BIOS clear screen](bios_clear_screen.S)
     1.  APM
         1.  [APM shutdown](apm_shutdown.S)
         1.  [APM shutdown 2](apm_shutdown2.S)
@@ -31,6 +34,8 @@ Hello world programs that run without an operating system.
 
     sudo apt-get install build-essential gnu-efi qemu nasm xorriso
 
+### Emulator
+
 Run the default program on QEMU:
 
     make run
@@ -42,7 +47,9 @@ Run a given program:
 
 Tested on Ubuntu 14.04 AMD64.
 
-To run on real hardware, insert an USB, determine its device (`/dev/sdX`) with:
+### Real hardware
+
+Insert an USB, determine its device (`/dev/sdX`) with:
 
     sudo lsblk
     sudo fdisk -l
@@ -58,3 +65,15 @@ Then:
 - choose to boot from the USB
 
 Tested on: ThinkPad T400.
+
+#### Big image
+
+Create a `big.img` that contains all examples that can be booted from GRUB:
+
+    make big-img
+
+Now if you do:
+
+    sudo dd if=big.img of=/dev/sdX
+
+you can test several examples with a single USB burn, which is much faster.

bios_carriage_return.S

@@ -0,0 +1,26 @@
+/*
+What happens when a newline is output with bios.
+
+Outcome:
+
+    hello
+         world
+
+Carriage returns are needed just like in old days.
+*/
+
+#include "common.h"
+BEGIN
+    mov $msg, %si
+    mov $0x0e, %ah
+loop:
+    lodsb
+    or %al, %al
+    jz halt
+    int $0x10
+    jmp loop
+halt:
+    hlt
+msg:
+    .asciz "hello\n\rworld"
+END

bios_clear_screen.S

@@ -0,0 +1,29 @@
+/*
+Clear screen by scrolling.
+*/
+
+#include "common.h"
+BEGIN
+
+/*
+Print one char to ensure that something will be claered.
+
+On some systems, BIOS messages get automatically cleared. Not the case for QEMU 2.0.0.
+*/
+mov $0x0E40, %ax
+int $0x10
+
+/* Function ID. */
+mov $0x06, %ah
+/* nr. of lines to scroll, 00 means clear window. */
+mov $0x0, %al
+/* TODO: I think this is the style. */
+mov $0x7, %bh
+/* CH,CL: row,column upper left corner (00:00) */
+mov $0x0, %cx
+/* DH,DL: row,column lower right corner (24:79) */
+mov $0x184f, %dx
+int $0x10
+
+hlt
+END

bios_newline.S

@@ -0,0 +1,26 @@
+/*
+What happens when a newline is output with bios.
+
+Outcome:
+
+    hello
+         world
+
+Carriage returns are needed just like in old days.
+*/
+
+#include "common.h"
+BEGIN
+    mov $msg, %si
+    mov $0x0e, %ah
+loop:
+    lodsb
+    or %al, %al
+    jz halt
+    int $0x10
+    jmp loop
+halt:
+    hlt
+msg:
+    .asciz "hello\nworld"
+END

bios_one_char.S

@@ -1,12 +1,16 @@
 /*
 Print a single `@` character with the BIOS.
+
 More minimal than the hello world.
 */
 
 #include "common.h"
 BEGIN
-mov $0x40, %al
+/*
-mov $0x0e, %ah
+40 == ASCII for '@'
+0E == BIOS function ID.
+*/
+mov $0x0E40, %ax
 int $0x10
 hlt
 END

grub/Makefile

@@ -0,0 +1,13 @@
+.POSIX:
+
+.PHONY: clean run
+
+main.img:
+	make -C '../mbrs' && cp '../bios_hello_world.img.sym' 'iso/boot/main.img'
+	grub-mkrescue -o '$@' iso
+
+clean:
+	rm -f iso/boot/*.img *.img
+
+run: main.img
+	qemu-system-i386 -hda '$<'

grub/chainloader/README.md

@@ -11,3 +11,5 @@ This example uses a file, but the most common way to use it is with:
     chainloader +1
 
 which uses the first sector of some partition instead of a file.
+
+TODO: why does it fail for hybrid ISO images? <http://superuser.com/questions/154134/grub-how-to-boot-into-iso-partition#comment1337357_154271>

grub/chainloader/iso/boot/grub/grub.cfg

@@ -1,5 +1,7 @@
-set timeout=0
+menuentry "hello-world" {
-set default="0"
-menuentry "main" {
     chainloader /boot/main.img
 }
+# Reload ourselves again.
+menuentry "self +1" {
+    chainloader +1
+}