Initial import

INSTALL

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+
+                    SOS: A Simple Operating System
+
+               Compilation/Installation/Test instructions
+
+
+Compilation
+===========
+
+IMPORTANT
+---------
+
+Don't forget to run 'make clean' before 'make' after you have modified
+any source or header file(s).
+
+
+On a x86 host where grub is correctly installed
+-----------------------------------------------
+
+Simply run 'make'
+
+
+On a non-x86 host (without grub of course !)
+--------------------------------------------
+
+See extra/README
+
+
+On an x86 host without Grub, or with a buggy Grub
+-------------------------------------------------
+
+See extra/README
+
+How do I know I have a buggy grub installation ? Answer: in the qemu
+PC emulator, Grub hangs while loading the kernel
+
+
+Installation
+============
+
+Nothing special to do besides compiling
+
+
+Test the SOS Kernel
+===================
+
+On a x86 real machine with Grub installed
+-----------------------------------------
+
+ 1st method
+   => Boot the sos.elf file (append 'kernel=<path_to>sos.elf' in the
+      menu.lst or type it on Grub's command line) from a hard disk, a
+      floppy, or from the network
+
+ 2nd method
+   => Copy the file 'fd.img' to a floppy and boot from it
+
+
+On a x86 real machine without Grub installed
+--------------------------------------------
+
+ 1st method
+   => see extra/README to compile with the grub floppy image we provide,
+      copy the file 'fd.img' to a floppy, and boot from it
+
+ 2nd method
+   => see extra/README to compile with the boot sector we provide (up to
+      article 2 only), copy the file 'extra/sos_bsect.img' to a floppy,
+      and boot from it
+
+
+Inside a PC emulator (x86 and non-x86 hosts)
+--------------------------------------------
+
+Tested on both the bochs emulator (x86/linux, sparc/solaris and
+ppc/linux hosts, 'apt-get install bochs-x vgabios' on debian
+testing/unstable), and the qemu system emulator (with libsdl
+installed: 'apt-get install libsdl1.2-dev' on debian
+testing/unstable).
+
+ 1/ Grub is installed on the host (x86 hosts only)
+ - - - - - - - - - - - - - - - - - - - - - - - - -
+
+   bochs: boot from the file 'fd.img'. Example of a ~/.bochsrc:
+     floppya:     1_44=/home/d2/sos/fd.img, status=inserted
+     romimage:    file=/usr/share/bochs/BIOS-bochs-latest, address=0xf0000
+     vgaromimage: /usr/share/vgabios/vgabios.bin
+     megs:63 # 63 Mo de RAM
+
+   qemu: run 'qemu -fda fd.img'
+     If grub hangs while loading the kernel, please go to method 2/
+
+ 2/ Grub is not installed (all hosts)
+ - - - - - - - - - - - - - - - - - -
+
+  See extra/README to generate a floppy image with the Grub floppy
+  image we provide, and:
+
+   bochs: boot from the file 'fd.img'
+
+   qemu: run 'qemu -fda fd.img'
+
+ 3/ Bonus: boot with the bootsector we provide (all hosts, up to art. 2 ONLY !)
+ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  
+  See extra/README to generate a floppy image with the boot sector we
+  provide, and:
+
+   bochs: boot from the file 'extra/sos_bsect.img'
+
+   qemu: run 'qemu -fda extra/sos_qemu.img'
+
+  NOTE: After article 2, this way of booting is not supported: please
+  use the method 2/ above.
+
+
+NOTE : recommended versions of the tools
+----------------------------------------
+ - OS           : Linux 2.6.11.7-d2-1 i686
+ - gcc          : gcc (GCC) 3.3.5 (Debian 1:3.3.5-8)
+ - GNU binutils : GNU ld version 2.15
+ - GNU make     : GNU Make 3.80
+
+Also tested with (on ppc/debian host):
+ - OS           : Linux 2.6.10-powerpc ppc
+ - gcc          : gcc (GCC) 3.2.2
+ - GNU binutils : GNU ld version 2.13.2
+ - GNU make     : GNU Make 3.80
+
+--
+David Decotigny

LICENSE

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+		    GNU GENERAL PUBLIC LICENSE
+		       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.
+                       59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+			    Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it.  (Some other Free Software Foundation software is covered by
+the GNU Library General Public License instead.)  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
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+
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+
+  For example, if you distribute copies of such a program, whether
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+
+  We protect your rights with two steps: (1) copyright the software, and
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+
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+  The precise terms and conditions for copying, distribution and
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+
+		    GNU GENERAL PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
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+
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+
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+
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+
+These requirements apply to the modified work as a whole.  If
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+
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+
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+
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+
+			    NO WARRANTY
+
+  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
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+
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+
+		     END OF TERMS AND CONDITIONS
+
+	    How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) 19yy  <name of author>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+    Gnomovision version 69, Copyright (C) 19yy name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Library General
+Public License instead of this License.

Makefile

@@ -0,0 +1,83 @@
+## Copyright (C) 2004,2005  The SOS Team
+##
+## This program is free software; you can redistribute it and/or
+## modify it under the terms of the GNU General Public License
+## as published by the Free Software Foundation; either version 2
+## of the License, or (at your option) any later version.
+## 
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+## 
+## You should have received a copy of the GNU General Public License
+## along with this program; if not, write to the Free Software
+## Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+## USA. 
+
+CC=gcc
+LD=ld
+CFLAGS  = -Wall -nostdinc -ffreestanding -DKERNEL_SOS
+LIBGCC := $(shell $(CC) -print-libgcc-file-name) # To benefit from FP/64bits artihm.
+LDFLAGS = --warn-common -nostdlib
+OBJECTS = bootstrap/multiboot.o					\
+          hwcore/idt.o hwcore/gdt.o				\
+	  hwcore/swintr.o hwcore/swintr_wrappers.o		\
+	  hwcore/exception.o hwcore/exception_wrappers.o	\
+	  hwcore/irq.o hwcore/irq_wrappers.o hwcore/i8259.o	\
+	  hwcore/paging.o 			                \
+	  hwcore/i8254.o drivers/x86_videomem.o drivers/bochs.o	\
+	  hwcore/cpu_context.o hwcore/cpu_context_switch.o	\
+	  hwcore/mm_context.o					\
+	  sos/kmem_vmm.o sos/kmem_slab.o sos/kmalloc.o		\
+	  sos/physmem.o sos/klibc.o				\
+	  sos/thread.o sos/kwaitq.o				\
+          sos/time.o sos/sched.o sos/ksynch.o			\
+	  sos/process.o sos/syscall.o				\
+          sos/assert.o sos/main.o sos/mouse_sim.o               \
+	  sos/uaccess.o sos/calcload.o				\
+          userland/userprogs.kimg sos/test-art7.o
+
+KERNEL_OBJ   = sos.elf
+MULTIBOOT_IMAGE = fd.img
+PWD := $(shell pwd)
+
+# Main target
+all: $(MULTIBOOT_IMAGE)
+
+$(MULTIBOOT_IMAGE): $(KERNEL_OBJ)
+	./support/build_image.sh $@ $<
+
+$(KERNEL_OBJ): $(OBJECTS) ./support/sos.lds
+	$(LD) $(LDFLAGS) -T ./support/sos.lds -o $@ $(OBJECTS) $(LIBGCC)
+	-nm -C $@ | cut -d ' ' -f 1,3 > sos.map
+	size $@
+
+-include .mkvars
+
+# Create the userland programs to include in the kernel image
+userland/userprogs.kimg: FORCE
+	$(MAKE) -C userland
+
+# Create objects from C source code
+%.o: %.c
+	$(CC) -I$(PWD) -c $< $(CFLAGS) -o $@
+
+# Create objects from assembler (.S) source code
+%.o: %.S
+	$(CC) -I$(PWD) -c $< $(CFLAGS) -DASM_SOURCE=1 -o $@
+
+FORCE:
+	@
+
+# Clean directory
+clean:
+	$(RM) *.img *.o mtoolsrc *~ menu.txt *.img *.elf *.bin *.map
+	$(RM) *.log *.out bochs*
+	$(RM) bootstrap/*.o bootstrap/*~
+	$(RM) drivers/*.o drivers/*~
+	$(RM) hwcore/*.o hwcore/*~
+	$(RM) sos/*.o sos/*~
+	$(RM) support/*~
+	$(RM) extra/*~
+	$(MAKE) -C userland clean

README

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+
+                    SOS: A Simple Operating System
+
+
+This   is   SOS,   a   Simple   Operating   System   for   i386-family
+processors. This is  as simple as possible to show a  way to program a
+basic Operating System on real  common hardware (PC).  The code should
+be easily readable and understandable thanks to frequent comments, and
+references to external documentation.  We chose to implement the basic
+features  of an OS,  thus making  design decisions  targetting towards
+simplicity  of  understanding,  covering  most  of  the  OS  classical
+concepts,  but  not  aiming  at  proposing  yet  another  full-fledged
+competitive OS  (Linux is  quite good at  it). However, for  those who
+would  like to  propose some  enhancements, we  are open  to  any code
+suggestions (patches only,  please).  And yes, there might  be bugs in
+the code, so please send us any bug report, and/or patches !
+
+The OS comes as  a set of articles (in french) to  be published in the
+journal  "Linux Magazine  France". Each  month, the  part of  the code
+related to the current article's theme is released (see VERSION file),
+and the resulting OS can  be successfully compiled and run, by booting
+it from a floppy on a real  machine (tested AMD k7, Cyrix and Intel P4
+pentiums), or through an x86  emulator (bochs or qemu).  The resulting
+OS is available as a multiboot compliant ELF kernel (sos.elf) and as a
+floppy image (fd.img).  It provides  a very very very basic demo whose
+aim is to  understand how everything works, not  to animate sprites on
+the screen with 5:1 dolby sound.
+
+The initial technical features and lack-of-features of the OS are:
+ - monolithic kernel, fully interruptible, non-preemptible (big kernel
+   lock), target machines = i386 PC or better
+ - compiles on any host where the gcc/binutils toolchain (target
+   i586-gnu) is available. Can be tested on real i486/pentium
+   hardware, or on any host that can run an i486/pentium PC emulator
+   (bochs or qemu)
+ - kernel loaded by grub, or by a sample bootsector (up to article 2
+   ONLY)
+ - clear separation of physical memory and virtual memory concepts,
+   even inside the kernel: no identity-mapping of the physical memory
+   inside the kernel (allows to move virtual mappings of kernel pages
+   at run-time, eg to free ISA DMA pages, and to avercome the 4G RAM
+   barrier)
+ - slab-type kernel memory allocation
+ - no swap, no reverse mapping
+ - VERY simple drivers: keyboard, x86 video memory, IDE disks
+ - logical devices: partitions, FAT filesystem, "hard-coded"
+   mountpoints only (~ MSDOS)
+ - no network stack
+ - user-level features: ELF loader (no shared libraries), processes,
+   user threads (kernel-level scheduling only), mmap API, basic VFS
+
+To understand where to look at for what, here is a brief description:
+ - Makefile: the (ONLY) makefile of the OS. Targets are basically
+   'all' and 'clean'
+ - bootstrap/ directory: code to load the kernel. Both the stuff
+   needed for a multiboot-compliant loader (eg grub) AND a bootsector
+   are provided. The bootsector may only be used up to article 2.
+ - sos/ directory: the entry routine for the kernel (main.c), various
+   systemwide header files, a set of common useful C routines
+   ("nano-klibc"), and kernel subsystems (kernel memory management,
+   etc...)
+ - hwcore/ directory: Low-level CPU- and kernel-related routines
+   (interrupt/exception management, translation tables and segment
+   registers, ...)
+ - drivers/ directory: basic kernel drivers for various (non CPU)
+   devices (keyboard, x86 video memory, bochs 0xe9 port, ...). Used
+   mainly for debugging
+ - support/ directory: scripts and configuration files to build the
+   floppy images
+ - extra/ directory: a set of configuration files to be customized for
+   non-x86 host installations (yes, we primarily develop SOS on a ppc, for
+   the x86 target of course), or for grub-less installations. See
+   README file in this directory.
+
+The code is licensed under the terms of the GNU GPL version 2 (see
+LICENSE file).
+
+Enjoy !
+
+                        David Decotigny, Thomas Petazzoni, the Kos team
+                                                   http://sos.enix.org/
+                                        http://david.decotigny.free.fr/
+                                           http://kos.enix.org/~thomas/
+                                                   http://kos.enix.org/
+
+
+--
+David Decotigny
+
+PS: Made with a Mac.

VERSION

@@ -0,0 +1,11 @@
+SOS -- Simple OS
+Copyright (C) 2003,2004,2005 The SOS Team (David Decotigny & Thomas Petazzoni)
+
+Version "Article 7 (1st part)" -- Basic user programs support
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; either version 2
+   of the License, or (at your option) any later version.
+
+   See the LICENSE file included in the distribution.

bootstrap/multiboot.S

@@ -0,0 +1,85 @@
+/* Copyright (C) 1999  Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; either version 2
+   of the License, or (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+   USA. 
+*/
+
+	
+/* The operating system is booted by Grub, so we almost have nothing
+   to do to boot it. We only have to conform to the Multiboot
+   standard, as defined by the Grub documentation */
+	
+#define ASM 1
+/* The multiboot.h header contains a lot of multiboot standard
+   definitions */
+#include "multiboot.h"
+
+	/* The multiboot header itself. It must come first. */
+.section ".multiboot"
+	/* Multiboot header must be aligned on a 4-byte boundary */
+	.align 4
+multiboot_header:
+  /* magic=        */ .long MULTIBOOT_HEADER_MAGIC
+  /* flags=        */ .long MULTIBOOT_HEADER_FLAGS
+  /* checksum=     */ .long -(MULTIBOOT_HEADER_MAGIC \
+                              +MULTIBOOT_HEADER_FLAGS)
+  /* header_addr=  */ .long multiboot_header
+  /* load_addr=    */ .long __b_load
+  /* load_end_addr=*/ .long __e_load
+  /* bss_end_addr= */ .long __e_kernel
+  /* entry_addr=   */ .long multiboot_entry
+	
+/* Here is the beginning of the code of our operating system */
+.text
+
+.globl start, _start
+start:
+_start:
+multiboot_entry:
+	/* Set up a stack */
+	movl $(stack + MULTIBOOT_STACK_SIZE), %ebp
+	movl %ebp, %esp
+
+	/* Set EFLAGS to 0 */
+	pushl $0
+	/* pop stack into the EFLAGS register */
+	popf
+
+	/* Push the magic and the address on the stack, so that they
+	will be the parameters of the cmain function */
+	pushl %ebx
+	pushl %eax
+
+	/* Call the cmain function (os.c) */
+	call EXT_C(sos_main)
+
+	/* Should never get there */
+loop:
+	hlt
+	jmp loop
+
+/* Here is the stack */
+.section ".init_stack", "aw", @nobits
+.size stack, MULTIBOOT_STACK_SIZE
+stack:
+	.space MULTIBOOT_STACK_SIZE
+
+/* Some data characterizing the stack addresses */
+.data
+	.globl bootstrap_stack_bottom
+bootstrap_stack_bottom: .long stack
+
+	.globl bootstrap_stack_size
+bootstrap_stack_size: .long MULTIBOOT_STACK_SIZE

bootstrap/multiboot.h

@@ -0,0 +1,133 @@
+#ifndef __MULTIBOOT_H__
+#define __MULTIBOOT_H__
+
+/* multiboot.h - the header for Multiboot */
+/* Copyright (C) 1999  Free Software Foundation, Inc.
+   
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+/* Macros.  */
+
+/* The magic number for the Multiboot header.  */
+#define MULTIBOOT_HEADER_MAGIC		0x1BADB002
+
+/* The flags for the Multiboot header.  */
+#define MULTIBOOT_HEADER_FLAGS		0x00010003
+
+/* The magic number passed by a Multiboot-compliant boot loader.  */
+#define MULTIBOOT_BOOTLOADER_MAGIC	0x2BADB002
+
+/* The size of our stack (16KB).  */
+#define MULTIBOOT_STACK_SIZE	        0x4000
+
+#define MULTIBOOT_CMDLINE 4
+#define MULTIBOOT_MODS 8
+
+/* C symbol format. HAVE_ASM_USCORE is defined by configure.  */
+#ifdef HAVE_ASM_USCORE
+# define EXT_C(sym)			_ ## sym
+#else
+# define EXT_C(sym)			sym
+#endif
+
+#ifndef ASM
+/* Do not include here in the assembler sources.  */
+
+#include <sos/types.h>
+
+/* The address of the stack of the bootstrap thread */
+extern sos_vaddr_t bootstrap_stack_bottom;
+extern sos_size_t bootstrap_stack_size;
+
+/* Types.  */
+
+/* The Multiboot header.  */
+typedef struct multiboot_header
+{
+  unsigned long magic;
+  unsigned long flags;
+  unsigned long checksum;
+  unsigned long header_addr;
+  unsigned long load_addr;
+  unsigned long load_end_addr;
+  unsigned long bss_end_addr;
+  unsigned long entry_addr;
+} multiboot_header_t;
+
+/* The symbol table for a.out.  */
+typedef struct aout_symbol_table
+{
+  unsigned long tabsize;
+  unsigned long strsize;
+  unsigned long addr;
+  unsigned long reserved;
+} aout_symbol_table_t;
+
+/* The section header table for ELF.  */
+typedef struct elf_section_header_table
+{
+  unsigned long num;
+  unsigned long size;
+  unsigned long addr;
+  unsigned long shndx;
+} elf_section_header_table_t;
+
+/* The Multiboot information.  */
+typedef struct multiboot_info
+{
+  unsigned long flags;
+  unsigned long mem_lower;
+  unsigned long mem_upper;
+  unsigned long boot_device;
+  unsigned long cmdline;
+  unsigned long mods_count;
+  unsigned long mods_addr;
+  union
+  {
+    aout_symbol_table_t aout_sym;
+    elf_section_header_table_t elf_sec;
+  } u;
+  unsigned long mmap_length;
+  unsigned long mmap_addr;
+  unsigned long drives_length;
+  unsigned long drives_addr;
+} multiboot_info_t;
+
+/* The module structure.  */
+typedef struct module
+{
+  unsigned long mod_start;
+  unsigned long mod_end;
+  unsigned long string;
+  unsigned long reserved;
+} module_t;
+
+/* The memory map. Be careful that the offset 0 is base_addr_low
+   but no size.  */
+typedef struct memory_map
+{
+  unsigned long size;
+  unsigned long base_addr_low;
+  unsigned long base_addr_high;
+  unsigned long length_low;
+  unsigned long length_high;
+  unsigned long type;
+} memory_map_t;
+
+void dump_multiboot_info(multiboot_info_t *mbi);
+
+#endif /* ! ASM */
+
+#endif /* __MULTIBOOT_H__ */

drivers/bochs.c

@@ -0,0 +1,123 @@
+/* Copyright (C) 2004  David Decotigny
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; either version 2
+   of the License, or (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+   USA. 
+*/
+#include <hwcore/ioports.h>
+#include <sos/klibc.h>
+
+#include "bochs.h"
+
+/* This is a special hack that is only useful when running the
+   operating system under the Bochs emulator.  */
+#define SOS_BOCHS_IOPORT 0xe9
+
+sos_ret_t sos_bochs_setup(void)
+{
+  return SOS_OK;
+}
+
+#define _putchar(chr) \
+    outb((chr), SOS_BOCHS_IOPORT)
+
+sos_ret_t sos_bochs_putchar(char c)
+{
+  _putchar(c);
+
+  return SOS_OK;
+}
+
+sos_ret_t sos_bochs_putstring(const char* str)
+{
+  for ( ; str && (*str != '\0') ; str++)
+    _putchar(*str);
+
+  return SOS_OK;
+}
+
+sos_ret_t sos_bochs_puthex(unsigned val, int nbytes)
+{
+  unsigned c;
+
+#define BOCHS_PRTHEX(q) \
+  ({ unsigned char r; if ((q) >= 10) r='a'+(q)-10; \
+     else r='0'+(q); _putchar(r); })
+
+  switch (nbytes)
+    {
+    case 4:
+      c = (val >> 24) & 0xff;
+      BOCHS_PRTHEX((c >> 4)&0xf);
+      BOCHS_PRTHEX(c&0xf);
+    case 3:
+      c = (val >> 16) & 0xff;
+      BOCHS_PRTHEX((c >> 4)&0xf);
+      BOCHS_PRTHEX(c&0xf);
+    case 2:
+      c = (val >> 8) & 0xff;
+      BOCHS_PRTHEX((c >> 4)&0xf);
+      BOCHS_PRTHEX(c&0xf);
+    case 1:
+      c = val & 0xff;
+      BOCHS_PRTHEX((c >> 4)&0xf);
+      BOCHS_PRTHEX(c&0xf);
+    }
+
+  return SOS_OK;
+}
+
+
+sos_ret_t sos_bochs_hexdump(const void* addr, int nbytes)
+{
+  int offs;
+  for (offs = 0 ; offs < nbytes ; offs++)
+    {
+      const unsigned char *c;
+      
+      if ((offs % 16) == 0)
+	{
+	  sos_bochs_putstring("0x");
+	  sos_bochs_puthex(offs, 4);
+	}
+      
+      if ((offs % 8) == 0)
+	sos_bochs_putstring("   ");
+
+      c = (const unsigned char*)(addr + offs);
+      sos_bochs_puthex(*c, 1);
+      sos_bochs_putstring(" ");
+      
+      if (((offs + 1) % 16) == 0)
+        sos_bochs_putstring("\n");
+    }
+
+  if (offs % 16)
+    sos_bochs_putstring("\n");
+
+  return SOS_OK;
+}
+
+
+sos_ret_t sos_bochs_printf(const char *format, /* args */...)
+{
+  char buff[256];
+  va_list ap;
+  
+  va_start(ap, format);
+  vsnprintf(buff, sizeof(buff), format, ap);
+  va_end(ap);
+  
+  return sos_bochs_putstring(buff);
+}

drivers/bochs.h

@@ -0,0 +1,55 @@
+/* Copyright (C) 2004  David Decotigny
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; either version 2
+   of the License, or (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+   USA. 
+*/
+#ifndef _SOS_BOCHS_H_
+#define _SOS_BOCHS_H_
+
+/**
+ * @file bochs.h
+ *
+ * If you compiled Bochs with the --enable-e9-hack, then any character
+ * printed to the 0xE9 I/O port is printed to the xterm that is
+ * running Bochs. This may appear to be a detail, but in fact, this
+ * functionnality is *VERY* precious for debugging purposes. This
+ * """driver""" handles this feature.
+ */
+
+#include <sos/errno.h>
+#include <sos/types.h>
+
+sos_ret_t sos_bochs_setup(void);
+
+sos_ret_t sos_bochs_putchar(char c);
+
+sos_ret_t sos_bochs_putstring(const char* str);
+
+/** Print the least signficant 32 (nbytes == 4), 24 (nbytes == 3), 16
+    (nbytes == 2) or 8 (nbytes == 1) bits of val in hexadecimal. */
+sos_ret_t sos_bochs_puthex(unsigned val, int nbytes);
+
+/** hexdump-style pretty printing */
+sos_ret_t sos_bochs_hexdump(const void* addr, int nbytes);
+
+/**
+ * Print the formatted string. Very restricted version of printf(3):
+ * 1/ can print max 255 chars, 2/ supports only %d/%i, %c, %s, %x
+ * without any support for flag charachters (eg %08x).
+ */
+sos_ret_t sos_bochs_printf(const char *format, /* args */...)
+     __attribute__ ((format (printf, 1, 2)));
+
+#endif

drivers/x86_videomem.c

@@ -0,0 +1,127 @@
+/* Copyright (C) 2004  David Decotigny
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; either version 2
+   of the License, or (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+   USA. 
+*/
+#include <sos/klibc.h>
+#include <hwcore/ioports.h>
+
+#include "x86_videomem.h"
+
+/* The text video memory starts at address 0xB8000. Odd bytes are the
+   ASCII value of the character, even bytes are attribute for the
+   preceding character. */
+#define VIDEO   0xb8000
+
+
+/* Console screen size */
+#define LINES   25
+#define COLUMNS 80
+
+
+/** The structure of a character element in the video memory. @see
+    http://webster.cs.ucr.edu/AoA DOS edition chapter 23 */
+typedef struct {
+  unsigned char character;
+  unsigned char attribute;
+} __attribute__ ((packed)) x86_video_mem[LINES*COLUMNS];
+
+
+
+/** The base pointer for the video memory */
+static volatile x86_video_mem *video = (volatile x86_video_mem*)VIDEO;
+
+sos_ret_t sos_x86_videomem_setup(void)
+{
+  /*
+   * Hide cursor. @see Ralf Brown's interrupt (and port) list
+   * http://www-2.cs.cmu.edu/~ralf/files.html
+   */
+#define CRT_REG_INDEX 0x3d4
+#define CRT_REG_DATA  0x3d5
+
+  /* CRT index port => ask for access to register 0xa ("cursor
+     start") */
+  outb(0x0a, CRT_REG_INDEX);
+
+  /* (RBIL Tables 708 & 654) CRT Register 0xa => bit 5 = cursor OFF */
+  outb(1 << 5, CRT_REG_DATA);
+
+  return SOS_OK;
+}
+
+
+sos_ret_t sos_x86_videomem_cls(unsigned char attribute)
+{
+  /* Clears the screen */
+  int i;
+  for(i = 0 ; i < LINES*COLUMNS ; i++)
+    {
+      (*video)[i].character = 0;
+      (*video)[i].attribute = attribute;
+    }
+
+  return SOS_OK;  
+}
+
+
+sos_ret_t sos_x86_videomem_putstring(unsigned char row, unsigned char col,
+				     unsigned char attribute,
+				     const char *str)
+{
+  unsigned video_offs = row*COLUMNS + col;
+
+  if (video_offs >= LINES*COLUMNS)
+    return -SOS_EINVAL;
+  
+  for ( ; str && *str && (video_offs < LINES*COLUMNS) ; str++, video_offs++)
+    {
+      (*video)[video_offs].character = (unsigned char)*str;
+      (*video)[video_offs].attribute = attribute;
+    }
+
+  return SOS_OK;
+}
+
+
+sos_ret_t sos_x86_videomem_putchar(unsigned char row, unsigned char col,
+				   unsigned char attribute,
+				   unsigned char c)
+{
+  unsigned video_offs = row*COLUMNS + col;
+
+  if (video_offs >= LINES*COLUMNS)
+    return -SOS_EINVAL;
+  
+  (*video)[video_offs].character = c;
+  (*video)[video_offs].attribute = attribute;
+
+  return SOS_OK;
+}
+
+
+sos_ret_t sos_x86_videomem_printf(unsigned char row, unsigned char col,
+				  unsigned char attribute,
+				  const char *format, /* args */...)
+{
+  char buff[256];
+  va_list ap;
+  
+  va_start(ap, format);
+  vsnprintf(buff, sizeof(buff), format, ap);
+  va_end(ap);
+  
+  return sos_x86_videomem_putstring(row, col, attribute, buff);
+}

drivers/x86_videomem.h

@@ -0,0 +1,97 @@
+/* Copyright (C) 2004  David Decotigny
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; either version 2
+   of the License, or (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+   USA. 
+*/
+#ifndef _SOS_X86_VIDEOMEM_H_
+#define _SOS_X86_VIDEOMEM_H_
+
+/**
+ * @file x86_videomem.h
+ *
+ * On x86 PC platforms, the text mode screen memory (and CGA/EGA/VGA
+ * too) is mapped into physical memory. This file handles access to
+ * this screen, supposed to be set in text-mode, through this memory
+ * area. All the functions below print the characters directly to the
+ * memory, without interpreting the escaped characters (such as \n,
+ * \r...)
+ */
+
+#include <sos/errno.h>
+
+/**
+ * x86 video attributes
+ * See http://webster.cs.ucr.edu/AoA/DOS/ch23/CH23-1.html
+ */
+/* Normal and Dark/Light foreground */
+#define SOS_X86_VIDEO_FG_BLACK     0
+#define SOS_X86_VIDEO_FG_DKGRAY    8
+#define SOS_X86_VIDEO_FG_BLUE      1
+#define SOS_X86_VIDEO_FG_LTBLUE    9
+#define SOS_X86_VIDEO_FG_GREEN     2
+#define SOS_X86_VIDEO_FG_LTGREEN   10
+#define SOS_X86_VIDEO_FG_CYAN      3
+#define SOS_X86_VIDEO_FG_LTCYAN    11
+#define SOS_X86_VIDEO_FG_RED       4
+#define SOS_X86_VIDEO_FG_LTRED     12
+#define SOS_X86_VIDEO_FG_MAGENTA   5
+#define SOS_X86_VIDEO_FG_LTMAGENTA 13
+#define SOS_X86_VIDEO_FG_BROWN     6
+#define SOS_X86_VIDEO_FG_YELLOW    14
+#define SOS_X86_VIDEO_FG_LTGRAY    7
+#define SOS_X86_VIDEO_FG_WHITE     15
+/* Background */
+#define SOS_X86_VIDEO_BG_BLACK     (0 << 4)
+#define SOS_X86_VIDEO_BG_BLUE      (1 << 4)
+#define SOS_X86_VIDEO_BG_GREEN     (2 << 4)
+#define SOS_X86_VIDEO_BG_CYAN      (3 << 4)
+#define SOS_X86_VIDEO_BG_RED       (4 << 4)
+#define SOS_X86_VIDEO_BG_MAGENTA   (5 << 4)
+#define SOS_X86_VIDEO_BG_BROWN     (6 << 4)
+#define SOS_X86_VIDEO_BG_LTGRAY    (7 << 4)
+/* Blinking */
+#define SOS_X86_VIDEO_FG_BLINKING  (1 << 7)
+
+
+/** Setup the video RAM mapping and clear the screen */
+sos_ret_t sos_x86_videomem_setup(void);
+
+/** Clears the screen and set the background color as given by
+    attribute */
+sos_ret_t sos_x86_videomem_cls(unsigned char attribute);
+
+/** Print the string on the scren with the given attribute. Does not
+    handle scrolling */
+sos_ret_t sos_x86_videomem_putstring(unsigned char row, unsigned char col,
+				     unsigned char attribute,
+				     const char *str);
+
+/** Print the character on the scren with the given attribute. Does not
+    handle scrolling */
+sos_ret_t sos_x86_videomem_putchar(unsigned char row, unsigned char col,
+				   unsigned char attribute,
+				   unsigned char c);
+
+/**
+ * Print the formatted string. Very restricted version of printf(3):
+ * 1/ can print max 255 chars, 2/ supports only %d/%i, %c, %s, %x
+ * without any support for flag charachters (eg %08x).
+ */
+sos_ret_t sos_x86_videomem_printf(unsigned char row, unsigned char col,
+				  unsigned char attribute,
+				  const char *format, /* args */...)
+     __attribute__ ((format (printf, 4, 5)));
+
+#endif /* _SOS_X86_VIDEOMEM_H_ */

extra/Makefile

@@ -0,0 +1,40 @@
+OBJCOPY=objcopy
+
+all: sos_qemu.img
+
+-include ../.mkvars
+
+# The image is the simple concatenation of the boot sector and the kernel
+# It may be use in bochs or on a real floppy, but NOT in qemu (see below)
+sos_bsect.img: bsect.bin sos.bin
+	cat $^ > $@
+	@echo "You can use the $@ image in bochs or on a real floppy (NOT qemu)"
+
+# For qemu, the trick is to tell it we have *more* than 1440 sectors (720kB).
+# Rtherwise the qemu disk geometry will be configured to be that of a 720kB
+# floppy, while our boot sector assumes it to be 1.44MB
+sos_qemu.img: sos_bsect.img
+	# Padding with 0s after the bsect/kernel image
+	cat $< /dev/zero | dd of=$@ bs=1k count=1440
+	@echo "You can use the $@ image in qemu, bochs, or on a real floppy"
+
+# we extract the boot sector from the main ELF binary
+bsect.bin: sos_bsect.elf
+	$(OBJCOPY) -v -O binary -j .bootsect $< $@
+
+# we extract the kernel code from the main ELF binary
+sos.bin: sos_bsect.elf
+	$(OBJCOPY) -v -O binary -R .bootsect $< $@
+
+# The main ELF binary contains the boot sector and the kernel code
+# linked together (hence we deal with a SINGLE image that we split
+# above) because they share some symbol definitions
+sos_bsect.elf: bootsect.o compile_kernel
+	$(LD) --warn-common -T ./sos_bsect.lds -o $@ \
+		bootsect.o $(wildcard ../hwcore/*.o ../drivers/*.o ../sos/*.o)
+
+compile_kernel:
+	$(MAKE) -C ..
+
+clean:
+	$(RM) *.img *.elf *.bin *~ *.o *.out

extra/README

@@ -0,0 +1,73 @@
+
+Contents of the extra/ directory
+================================
+
+Data and configuration files to support generation of sos on non-x86
+and/or grub-less hosts:
+ - dot.mkvars: file to copy as .mkvars in the root directory to
+   compile on a non-x86 host, and to generate the grub floppy image on
+   a grub-less host
+ - grub.img.gz: compressed image of a Grub floppy (without any
+   kernel). Used by dot.mkvars.
+ - mtoolsrc: file needed by .mkvars to compile a the floppy image
+
+Support of a sos-specific boot sector:
+ - Makefile: rules to compile sos_bsect.img, the floppy image with the
+   boot sector and the Sos
+ - bootsect.S: x86 Sos boot sector (GNU as). Depends on sos_bsect.lds
+ - sos_bsect.lds: ld script to bind the boot sector with the remaining
+   of the kernel
+
+Misc:
+ - qemu-port-e9.diff: patch over qemu to support the bochs "port 0xe9 hack"
+
+
+What you can do with these files
+================================
+
+
+*** Compile SOS from another architecture:
+------------------------------------------
+ - compile a cross-compiler for the i586-gnu target. This involves
+   compiling the binutils and gcc. Here are example configuration
+   options for them:
+   binutils (replace sparc-cun-solaris with your arch):
+     ../binutils-2.13/configure --prefix=/udd/ddecotig/temp_dd/xgcc/host-sparc-solaris7/stow/binutils-2.11 --host=sparc-sun-solaris2.7 i586-gnu
+     make && make install
+   gcc (ditto):
+     CFLAGS="-O2 -Dinhibit_libc" ../gcc-3.2/configure --target=i586-gnu --prefix=/udd/ddecotig/temp_dd/xgcc/host-sparc-solaris7/stow/gcc-3.2 --with-as=/udd/ddecotig/temp_dd/xgcc/host-sparc-solaris7/bin/as --with-ld=/udd/ddecotig/temp_dd/xgcc/host-sparc-solaris7/bin/ld --with-gnu-as --with-gnu-ld --enable-languages=c --disable-shared --disable-multilib --disable-nls --enable-threads=single
+     make && make install
+ - compile the mtools
+ - copy dot.mkvars to the root directory of SOS, as ".mkvars"
+ - customize the CC/LD/... variables to suit your cross-compiler
+   installatioon
+ - now you may run make from the SOS root directory, it should
+   generate the Grub boot floppy image. The following warning is
+   normal:
+     .mkvars:16: attention : écrasement des commandes pour la cible « grub-sos.img »
+     Makefile:92: attention : anciennes commandes ignorées pour la cible « grub-sos.img »
+
+
+*** To compile SOS from an x86 where grub is not or incorrectly installed:
+--------------------------------------------------------------------------
+ - copy dot.mkvars to the root directory of SOS, as ".mkvars"
+ - customize the CC/LD/... variables to suit your cross-compiler
+   installatioon
+ - now you may run make from the SOS root directory, it should
+   generate the Grub boot floppy image. The following warning is
+   normal:
+     .mkvars:16: attention : écrasement des commandes pour la cible « grub-sos.img »
+     Makefile:92: attention : anciennes commandes ignorées pour la cible « grub-sos.img »
+
+
+*** To compile SOS with its own bootloader:
+-------------------------------------------
+ - for cross-architecture compilation: see above
+ - cd to this extra/ directory
+ - run 'make'
+ - the floppy image is: sos_bsect.img
+ NOTE : SOS will not boot correctly this way after article 2 !
+
+
+--
+David Decotigny

extra/bootsect.S

@@ -0,0 +1,406 @@
+
+/*
+ * @(#) $Id: bootsect.S,v 1.8 2004/11/20 16:00:11 d2 Exp $
+ * Description : Bootsecteur en syntaxe AT&T
+ * Auteurs : Thomas Petazzoni & Fabrice Gautier & Emmanuel Marty
+ *	     Jerome Petazzoni & Bernard Cassagne & coffeeman
+ *	     David Decotigny
+ * Bug reports to kos-misc@enix.org
+ */
+
+/*
+ * But global de ce bootsecteur :
+ *
+ *		- Initialiser la becane
+ *		- Charger le kernel
+ *		- Passer en mode protege
+ *		- Executer le kernel
+ *
+ * Taille restante : Je vous rappelle qu'un bootsecteur ne peut faire
+ * qu'au maximum 512 octets dont 2 octets obligatoires 0xAA55.  Sur
+ * les 510 octets reellement utilisables, il reste 3 octets dispo (60
+ * si on decide d'enlever le BPB un jour) !!!
+ *
+ * thomas_petazzoni :  - detection des codes d'erreurs de chargement
+ * David_Decotigny  :  - Passage en GNU as
+ * David_Decotigny  :  - Chargement du noyau au-dela du 1er Mega (taille
+ *                       max = 0x9e000 octets = 632ko), pour avoir le
+ *                       meme noyau sous grub et avec le bootsecteur
+ */
+
+ /*
+  * Sequence d'operations :
+  * - Le BIOS charge le bootsect en 0x7c00 (BOOT_ADRESS). On choisit
+  *   la representation 0x7c0:0000 pour que le .org 0 reste valide
+  * - Le bootsect se deplace de lui-meme en 0x9f000 (COPY_ADRESS). On
+  *   choisit la representation 0x9f00:0000 pour que le .org 0 reste
+  *   valide
+  * - Le bootsect verifie que le processeur est du type 386+
+  * - Il charge le noyau depuis la disquette en memoire a partir de
+  *   0x1000 (LOAD_ADRESS). Le noyau peut au max tenir sur
+  *   SECTORS_TO_LOAD secteurs
+  * - Il passe en pmode flat (apres ouverture a20)
+  * - Il recopie le noyau (situe en LOAD_ADRESS) vers son adresse
+  *   finale (FINAL_ADDRESS = 2Mo). La recopie se fait sur tout l'espace
+  *   LOAD_ADRESS ---> COPY_ADRESS, c'est a dire sur 0x9e000 octets =
+  *   632ko. Le noyau peut donc au max faire 632ko. Le nombre max de
+  *   secteurs de disquette qu'on peut charger est donc 1264
+  */
+
+
+/* La taille de la pile */
+#define BOOT_STACK_SIZE	        0x4000
+
+	.file	"bootsect.S"
+
+	/* Tout est place dans une seule section */
+	.section ".bootsect"
+
+	/* L'essentiel du bootsector (sauf les 1eres instructions)
+	   sont a un offset 0. On fait en sorte que le compilo soit
+	   d'accord la-dessus. Quand on a des adresse realm exotiques
+	   (0x7c00, 0x9f000, ...), on s'arrange toujours pour avoir un
+	   offset de 0 => on choisira le segment adapte (0x7c0,
+	   0x9f00, ...). Il ne faut pas oublier le ld -Ttext 0 */
+	.org 0
+
+	/* Pour que gas genere du 16bits, afin que ca marche en realm */
+	.code16
+
+#define SECTORS_TO_LOAD 128 /* 64 ko */ /* MAX=1264 */
+
+/*
+ * Parametres de la disquette. Comme c'est chiant de faire une
+ * procedure de detection auto, et que ca prend de la place, on fait
+ * ca "a la main". Par exemple, une DD 720 Ko a 9 secteurs/piste, une
+ * 1.44 Mo a 18 secteurs/pistes
+ */
+#define CYLS    80
+#define HEADS   1
+#define SECTS   18
+
+#define BOOT_ADRESS 0x07C00  	       /* Adresse de demarrage (lineaire) */
+#define BOOT_SEG (BOOT_ADRESS>>4)      /* Segment de Boot */
+#define BOOT_SIZE 512		       /* Taille bu bootsecteur */
+#define COPY_ADRESS 0x9F000  	       /* La ou on va copier le
+					  bootsecteur (lineaire) */
+#define COPY_SEG (COPY_ADRESS>>4)      /* Segment de la ou on va
+					  copier le bootsecteur */
+#define LOAD_ADRESS 0x01000  	       /* 1er chargement du systeme */
+#define LOAD_SEG (LOAD_ADRESS>>4)      /* Segment du 1er chargement du */
+#define MAX_KERN_LEN COPY_ADRESS-LOAD_ADRESS /* Taille noyau maxi */
+
+/* IMPORTANT : Cette valeur DOIT etre identique a l'adresse presente
+	       dans sos.lds ! */
+#define FINAL_ADDRESS 0x200000         /* Adresse finale (physique de 0 a 4G)
+	                                  ou est charge le noyau */
+
+#define OP16 .byte 0x66 ;
+#define OP32 .byte 0x66 ;
+
+/*
+ * Procedure qui vide le buffer clavier.
+ */
+#define WAITKB     \
+  1:               ;\
+    .word 0xeb     ;\
+    .word 0xeb     ;\
+    inb $0x64, %al ;\
+    andb $0x2, %al ;\
+    jnz 1b
+
+	/* Le point d'entree dans le bootsect */
+.globl _bsect
+_bsect:
+
+	/*
+	 * La portion qui suit est situee a un offset 0x7c00 en
+	 * memoire. Attention donc aux references memoire dans cette
+	 * partie. On choisit de rester en offset 0 (.org 0), mais on
+         * charge correctement les segments a 0x7c0.
+         */
+
+	movw $BOOT_SEG, %ax /* le bootsecteur est a 0x7C00 en lineaire */
+	movw %ax, %ds      /* on le copie a l'adresse COPY_ADRESS */
+	xorw %si, %si      /* comme cette adresse est la plus haute de la mem */
+	xorw %di, %di      /* on pourra charger un kernel + gros */
+	movw $(BOOT_SIZE>>1), %cx
+	movw $COPY_SEG, %ax
+	movw %ax, %es
+	cld
+	rep ; movsw
+			
+	/* on continue a executer le bootsecteur, mais maintenant a
+           partir de 0x9F000, qu'on represente sous la forme
+           0x9f00:offset */
+	ljmp $COPY_SEG, $here
+
+	/*
+	 * A partir de maintenant, on est a un offset 0 en memoire
+         * (segment 0x9f00), conformement a ce que veut le compilo.
+	 */
+here:
+	movw %ax, %ds
+
+	/* Petite pile temporaire (1k - 3.84k en RAM ; les adresses 0-1k
+	   correspondent au vecteur d'interruptions). */
+	movw %ax, %ss
+    	movw $(LOAD_ADRESS - 0x10), %sp
+        
+	/* Efface l'ecran */
+	movb $0x0, %ah
+	movb $0x3, %al
+	int 	$0x10
+
+	/* Affiche les messages d'attente */
+	movw $loadkern, %si
+	call message
+	movw $check, %si
+	call message
+
+check386:
+	/*
+	 * la attention, plus complexe : on teste si le proc est un
+	 * 386+ pour cela, on va essayer de modifier les bits 12 ? 14
+	 * du registre E-flag si la modification reste, alors le proc
+	 * est un 386+, sinon, c'est =< 286
+	 *
+	 * Merci a Emmanuel Marty pour la compatibilite avec les 386
+	 * "pre-jurassique"
+	 */
+
+	pushf /* on sauvegarde le E-Flag */
+	movb $0x70, %ah
+	pushw %ax
+	popf
+	pushf
+	popw %ax
+	orb %ah, %ah
+	je no386  /* si la modif n'est pas valable, alors on saute a
+                     no386 */
+	popf      /* on les restaure ? la fin ... */
+
+	/* Message de confirmation de 386+ et d'attente */
+        movw $found386, %si
+	call message
+	movw $loading, %si
+	call message
+
+/* Copie du noyau disquette => RAM a partir de 0x1000
+   L'adresse de destination est définie par es:0, où es vaut
+   initialement 0x100 (ie correspond alors à l'adresse 256*16, soit 4
+   ko). Chaque itération incrémente ce registre es de 32, ce qui
+   correspond à un bond de 32*16 en mémoire, soit la taille d'un
+   secteur. De cette façon, puisqu'on joue sur les segments plutôt que
+   sur les offsets, la taille du noyau n'est pas limitée à 64 ko. Elle
+   est limitée par contre à la taille de la mémoire disponible sous
+   les 1Mo, \ie 640 ko (0x9f000 - 0x1000).  */
+copyKernel:
+	/* Chargement du noyau en LOAD_SEG:0 */
+	/* 3 iterateurs :
+		- load_size : le nbre de secteurs a charger
+		- cl : le secteur ou on en est pour le
+		  cylindre en cours (<= SECTS)
+		- dh : la tete en cours (0/1)
+	*/
+	movb $0, %dl
+	movw $LOAD_SEG, %ax
+	movw %ax, %es
+
+	xorw %bx, %bx
+	xorw %dx, %dx
+	movw $1, %cx  	 /*  premier secteur */
+
+.nextsector:         	 /* prochain secteur */
+	incb %cl    	 /* en incrementant CL */
+	cmpb $SECTS, %cl /* si CL =< SECTS (=nbre de secteurs/pistes)
+			    alors on charge */
+	jbe .sector
+	movb $1, %cl     /* sinon on revient au secteur 1 */
+	incb %dh         /* mais sur l'autre tete */
+	cmpb $1, %dh     /* on recompare, si DH =< 1 */
+	je .sector	 /* on charge */
+	movb $0, %dh     /* sinon on repasse a la tete 0 */
+	incb %ch         /* mais on change de cylindre */
+
+.sector:
+	pushw %es
+	movw $0x0201, %ax /* service 0x2, chargement 0x1 seecteur */
+	int $0x13          /* Go ! */
+	jc halt           /* erreur */
+	popw %ax