From bf4556b97210201feb430cd16d3da6d54689a0df Mon Sep 17 00:00:00 2001
From: Ciro Santilli <ciro.santilli@gmail.com>
Date: Sat, 12 Sep 2015 11:37:30 +0200
Subject: [PATCH] Infinite loop, rm .elf output

---
 .gitignore                                      |   1 +
 bios_one_char.S                                 |   7 +++++--
 infinite_loop.S                                 |  11 +++++++++++
 multiboot/README.md                             |   2 +-
 multiboot/hello-world/Makefile                  |   5 +++--
 multiboot/hello-world/isodir/boot/grub/grub.cfg |   3 +++
 multiboot/hello-world/main.elf                  | Bin 9638 -> 0 bytes
 template.S                                      |   4 ++++
 8 files changed, 28 insertions(+), 5 deletions(-)
 create mode 100644 infinite_loop.S
 create mode 100644 multiboot/hello-world/isodir/boot/grub/grub.cfg
 delete mode 100755 multiboot/hello-world/main.elf
 create mode 100644 template.S

diff --git a/.gitignore b/.gitignore
index 3c3aac9..04443a8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 *.bin
 *.efi
+*.elf
 *.img
 *.iso
 *.o
diff --git a/bios_one_char.S b/bios_one_char.S
index 084d864..617fbe8 100644
--- a/bios_one_char.S
+++ b/bios_one_char.S
@@ -1,5 +1,8 @@
-# Print a single `@` character with the BIOS.
-# More minimal than the hello world.
+/*
+Print a single `@` character with the BIOS.
+More minimal than the hello world.
+*/
+
 #include "common.h"
 BEGIN
 mov $0x40, %al
diff --git a/infinite_loop.S b/infinite_loop.S
new file mode 100644
index 0000000..48cc960
--- /dev/null
+++ b/infinite_loop.S
@@ -0,0 +1,11 @@
+/*
+This is a common alternative to `hlt`.
+
+It likely wastes more energy? But is less prone to being interrupted than `hlt`.
+*/
+
+#include "common.h"
+BEGIN
+loop:
+jmp loop
+END
diff --git a/multiboot/README.md b/multiboot/README.md
index fade8b9..223e62b 100644
--- a/multiboot/README.md
+++ b/multiboot/README.md
@@ -25,4 +25,4 @@ GRUB leaves the application into a well defined starting state.
 
 It seems that Linux does not implement Multiboot natively, but GRUB supports it as an exception: <http://stackoverflow.com/questions/17909429/booting-a-non-multiboot-kernel-with-grub2>
 
-Use `grub-mkrescue` to make a multiboot file into a bootable disk.
+Use `grub-mkrescue` and `grub-mkdisk` to make a multiboot file into a bootable ISO or disk.
diff --git a/multiboot/hello-world/Makefile b/multiboot/hello-world/Makefile
index a9604eb..d7d9902 100644
--- a/multiboot/hello-world/Makefile
+++ b/multiboot/hello-world/Makefile
@@ -1,11 +1,12 @@
+# main.elf is the main output: the multiboot file.
 main.elf: entry.o main.o
 	ld -m elf_i386 -nostdlib -T linker.ld -o '$@' $^
 
 entry.o: entry.asm
-	nasm -f elf '$<' -o '$@'
+	nasm -f elf32 '$<' -o '$@'
 
 main.o: main.c
-	gcc -c -m32 -std=c99 -ffreestanding -fno-builtin -Os -Wall -Wextra -o '$@' '$<'
+	gcc -c -m32 -std=c99 -ffreestanding -fno-builtin -Os -o '$@' -Wall -Wextra '$<'
 
 clean:
 	rm -f *.elf *.o
diff --git a/multiboot/hello-world/isodir/boot/grub/grub.cfg b/multiboot/hello-world/isodir/boot/grub/grub.cfg
new file mode 100644
index 0000000..436dd09
--- /dev/null
+++ b/multiboot/hello-world/isodir/boot/grub/grub.cfg
@@ -0,0 +1,3 @@
+menuentry "main" {
+	multiboot /boot/main.bin
+}
diff --git a/multiboot/hello-world/main.elf b/multiboot/hello-world/main.elf
deleted file mode 100755
index 44383cd2233e5d1a03a97b29fec340583c249022..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

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diff --git a/template.S b/template.S
new file mode 100644
index 0000000..48c2e1d
--- /dev/null
+++ b/template.S
@@ -0,0 +1,4 @@
+#include "common.h"
+BEGIN
+hlt
+END