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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

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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
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When we speak of free software, we are referring to freedom, not
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To protect your rights, we need to make restrictions that forbid
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We protect your rights with two steps: (1) copyright the software, and
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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
under the terms of this General Public License. The "Program", below,
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either verbatim or with modifications and/or translated into another
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the term "modification".) Each licensee is addressed as "you".
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running the Program is not restricted, and the output from the Program
is covered only if its contents constitute a work based on the
Program (independent of having been made by running the Program).
Whether that is true depends on what the Program does.
1. You may copy and distribute verbatim copies of the Program's
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conspicuously and appropriately publish on each copy an appropriate
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notices that refer to this License and to the absence of any warranty;
and give any other recipients of the Program a copy of this License
along with the Program.
You may charge a fee for the physical act of transferring a copy, and
you may at your option offer warranty protection in exchange for a fee.
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c) If the modified program normally reads commands interactively
when run, you must cause it, when started running for such
interactive use in the most ordinary way, to print or display an
announcement including an appropriate copyright notice and a
notice that there is no warranty (or else, saying that you provide
a warranty) and that users may redistribute the program under
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License. (Exception: if the Program itself is interactive but
does not normally print such an announcement, your work based on
the Program is not required to print an announcement.)
These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the Program,
and can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
sections when you distribute them as separate works. But when you
distribute the same sections as part of a whole which is a work based
on the Program, the distribution of the whole must be on the terms of
this License, whose permissions for other licensees extend to the
entire whole, and thus to each and every part regardless of who wrote it.
Thus, it is not the intent of this section to claim rights or contest
your rights to work written entirely by you; rather, the intent is to
exercise the right to control the distribution of derivative or
collective works based on the Program.
In addition, mere aggregation of another work not based on the Program
with the Program (or with a work based on the Program) on a volume of
a storage or distribution medium does not bring the other work under
the scope of this License.
3. You may copy and distribute the Program (or a work based on it,
under Section 2) in object code or executable form under the terms of
Sections 1 and 2 above provided that you also do one of the following:
a) Accompany it with the complete corresponding machine-readable
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integrity of the free software distribution system, which is
implemented by public license practices. Many people have made
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This section is intended to make thoroughly clear what is believed to
be a consequence of the rest of this License.
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certain countries either by patents or by copyrighted interfaces, the
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may add an explicit geographical distribution limitation excluding
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the limitation as if written in the body of this License.
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of the General Public License from time to time. Such new versions will
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either of that version or of any later version published by the Free
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Foundation.
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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
OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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REPAIR OR CORRECTION.
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WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
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INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.
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.

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## 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

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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.

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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.

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/* 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

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#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__ */

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/* 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);
}

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/* 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

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/* 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);
}

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/* 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_ */

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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

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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

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/*
* @(#) $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.