####[ How-Do-I Documents ]###################################
Sub : Loadlin Boots HDI #001
How-Do-I enable a multi-boot system where my M$-Win is on the
first partition and I have Linux on the other, below the 1024
cylinder limit of LILO ?
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Contents:
1. What is Loadlin
2. Where to get Loadlin
3. Why use Loadlin
4. Various options for booting Linux
5. How Loadlin works
6. How do you go about using loadlin
o Down-loading loadlin
o Copying kernel to M$ partition
7. Subsequent M$ TO-DOs
8. Loadlin and MS-DOS
9. How to make a Loadlin boot disk
10. Some other handy utilities
11. Appendices
a) Sample msdos.sys
b) Sample config.sys
c) Sample autoexec.bat
12. Kudos and brickbats
###############################################################
1. What is Loadlin
1.1 This is a boot loader for Linux that runs under MSDOS.
It can boot Linux from a DOS prompt or CONFIG.SYS, and
fully supports the command line feature of the Linux
kernel. This also supports bzImage+initrd, i.e it can
load directly 'high' and can load the ramdisk. The DOS
program was originally written by Hans Lerman. Later
versions were jointly developed along with Werner
Almesberger (author of LILO).
1.2 Loadlin is a boot loader for Linux. It operates from a
DOS partition (or a DOS formatted diskette).LOADLIN is
an utility which starts a "logical reload" of your
machine, causing DOS to be completely overlaid with
Linux. When you wish to return to DOS you must use the
Linux "reboot" command, since DOS is no longer active.
1.2 Loadlin is written completely in TASM (3.0) and there-
fore a x86 DOS binary. LOADLIN is highly adaptable to
different DOS configurations, and now has very few
loading restrictions. It makes use of extended memory
and can load big kernels and ramdisk images directly.
It is also capable of booting a UMSDOS-based system
from a DOS drive.
2 Where to get Loadlin
2.1 Normally Loadlin comes with the distribution diskettes
of nearly all distros ... If not, down-load it from :
ftp://elserv.ffm.fgan.de/pub/linux/loadlin-1.6/
3 Why use loadlin
3.1 There are several reasons. The default boot loader for
Linux is LILO (Linux Loader). The older versions had a
few limitations:
a) Inability to load from UMSDOS systems
b) The "1024-voodoo" ... explained below
c) Inability to load multiple operating systems on the
same box e.g. Win+Linux+QNX+BeOS
3.2 All these limitations are overcome by Loadlin. There is
also an added advantage, in that, since the Master Boot
Record (MBR) is MSDOS/ Windows, there are no problems
with some virus scanners which frown at the altered MBR
(boot sector).
3.3 The 1024-voodoo
3.3.1 The Master Boot Record (MBR) contains a tiny program
which has just enough information and code to load ano-
ther program placed somewhere else on your hard disk to
continue the booting process. The MBR does not have the
space to store much code (< 512 bytes). LILO depends on
the BIOS API to read from hard disk. With older BIOSes
the hard disk geometry is defined in C/H/S (Cylinder/
Head/Sector) format which can go upto a maximum of 1024
cylinders. LILO therefore failed if the root partition
was located beyond 1024 cylinders ... 1024-voodoo !
3.3.2 This limitation has been circumvented in newer LILOs
(ver 21.4 and beyond), provided you have a newer BIOS
providing disk geometry in Linear Block Addressing form
(LBA).
3.4 The M$ problem
3.4.1 All M$ OSs always occupy the MBR by default. There is
absolutely no compromise on this issue. If you put LILO
on the MBR, control actually passes over to Linux which
if located above the first 1024 cylinders, fails to do
a successful boot.
4. Various options for booting Linux
4.1 Since there are problems with the default Linux loader
(LILO) in certain situations alternatives available are
a) Repartition hard disk in such a way to keep the root
partition within the 1024 cylinder limit, use LILO..
This may not be a viable option if there is a lot of
data already installed on the Win/ DOS partition.
b) Boot into MSDOS/ Win and use a DOS program to boot
into Linux (e.g. Loadlin)
c) Use independent boot managers like partition magic.
All these boot loaders normally run from a primary
partition where the executables and data are kept.
Since an IDE hard drive can have a max of 4 primary
partitions, you effectively lose one Primary parti-
tion (and one less OS can be installed).
5 How Loadlin works.
5.1 The normal boot process of booting on an x86 platform
is as follows:
5.1.1 On initial power up, control is passed on to the BIOS
which checks configuration as saved in the CMOS, does
a probe of all hardware interfaces, and then reads the
MBR of the selected device (be it Hard disk, floppy or
the CDROM).
5.1.2 The code on the MBR directs control to another booting
program, which in M$ systems are 2 hidden/ system files
(io.sys and msdos.sys), followed by loading of command
interpreter command.com. After this configuration pref-
erences are loaded from config.sys, and programs to be
run at boot through autoexec.bat.
5.1.3 In this sequence the first level from where control can
be transferred is [config.sys], and subsequently, from
[autoexec.bat]. If Linux kernel is booted from autoexec
some amount of memory would be taken up by the programs
initiated from config.sys. Requirement to remove these
programs from memory therefore arise.
5.1.4 For Loadlin boots, the Linux kernel must be kept within
the M$ partition (not Linux /boot). The kernel itself
should be correctly pointed to the "/" partition where
Linux is installed. All that Loadlin does is to load
the kernel, which once loaded, can access all the ext2
partitions of your installation. The Linux init process
then commences normally as in LILO.
6 How do you go about using loadlin
6.1 Loadlin can successfully operate from any DOS or Win-9x
boot. The development of Loadlin ceased in 97-98, and
Win32 was the last thing added. There is no intrinsic
support for Win-NT or other M$ OSs like Win-2k, ME etc.
released subsequently.
6.2 Conceptually, being a pure Win-32 executable, it should
be operable on any system where config.sys or autoexec.
bat can be trapped. However I have not personally tried
it, and therefore, the rest of the methods described
pertain to MSDOS and Win-9x.
6.3 Down-loading Loadlin.
6.3.1 Loadlin comes as a zipped file. It can be downloaded or
copied to the M$ partition, and unzipped with any of
the unzipping tools (e.g. pkzip, winzip etc). There is
only one program of importance loadlin.exe, the others
are documentation, program source etc.
6.3.2 Make an independent directory in your M$ partition:
C:>mkdir C:\loadlin
Copy loadlin.exe to it ( optionally documentation can
also be copied there). Read all the doc files ...
6.4 Transferring kernel (vmlinuz) to M$ partition
6.4.1 As stated in Para 5.1.4, the kernel also needs to be
kept in the same directory ... only that at this stage
there is no kernel image available, unless you have
already installed Linux, and have made a boot disk.
6.4.2 If you have made a boot disk already, and have Linux
already installed, to run from (say /dev/hda2), the
kernel image should already be pointed correctly. It
is, however, safer to check.
6.4.3 If you have not installed Linux, nor have a boot disk,
there is no go ... you have to install Linux first. On
a pre-existing M$/ Win-9x box, first step is to ensure
you have a M$/ Win boot floppy at hand so that you can
do a fdisk /mbr to get back into M$/Win. At this stage
go and install Linux using the installation method for
your distro. At the end of it all LILO needs to be put
in place ... DO NOT put LILO on the MBR. Just place it
on the boot sector of your "/" (root) partition .. AND
ensure you make a boot disk. Once this is done, exit.
At this stage, you will be able to boot into M$/ Win9x
through hard disk, and into Linux with boot disk only.
The situation is good enough.
6.4.4 To copy your kernel (vmlinuz) to M$ partition you have
to go through Linux. M$/ Win cannot access ext2 parti-
tions. After booting, step [#1] is to identify kernel
image. In most distros this is kept in /boot. ( Note :
the kernel image may have a name of vmlinuz, zimage or
bzImage )
#cd /boot
#ls -al vmlinuz*
6.4.4.1 For each of these do:
#file vmlinuz.. (whatever)
6.4.4.2 One of these will show "Linux kernel x86 boot execut-
able". This is the file to be copied.
6.4.4.3 Next step is to see that this is correctly pointed to
your "/" (root) device.
#rdev vmlinuz
6.4.4.4 You will get a response like /dev/hda2. If this is okay
leave it alone, otherwise change it for your "/":
#rdev vmlinuz /dev/hda3 (or wherever your "/" lies)
6.4.4.5 Now you are assured that the kernel has been identified
and that it is correctly pointed. Next step is to mount
the M$ partition. You need a mount point for that. For
many distros a default /mnt is created at installation.
Otherwise you need to create a mount point:
#mkdir /mnt
6.4.4.6 Next mount the partition
#mount -t msdos /dev/hda1 /mnt
(assuming that /dev/hda1 is your M$ partition. Note:the
partition is being loaded as msdos and NOT vfat. This
is because, in most stock kernels of nearly all distros
msdos support in statically compiled, whereas vfat is
not. vfat support needs to be compiled or loaded as a
module for long filenames to work).
6.4.4.7 If you do a "ls /mnt" you should be able to see the
directory structure of M$ partition with all file names
truncated to 8.3 since you mounted it a M$. No harm ...
Now copy the kernel. Kernels may have name which is not
in the 8.3 format. Ensure that the filename written to
the M$ directory follows the 8.3 convention. E.g.:
#cp /boot/kernel-2.2.16 /mnt/loadlin/vmlinuz
6.4.4.8 That is about all there is to it. Your kernel image has
been copied to C:\loadlin\vmlinuz.
6.4.5 Once this is done .. exit from Linux. The rest of it is
to be done from M$/ Win.
7 Subsequent M$ TO-DOs
7.1 The test floppy
7.1.1 There is no magic here. The secret is in Win-9x rescue
disks. You notice that in Win-9x rescue disks you get a
menu on boot? That is because in Win9x, the hidden file
msdos.sys is an ASCII file! Make a spare Win-9x rescue/
boot disk and play around on that first.
C:\> attrib -h -s -r a:\msdos.sys
C:\> copy msdos.sys msdos1.sys
C:\> attrib +h +s +r a:\msdos.sys
[Read msdos1.sys well ... there are no changes needed.
You will see that MultiBoot has been enabled]
7.1.2 What a valid Win-98 looks like is pasted at Appendix "A"
7.1.3 Make a Win-9x boot disk first, and play around with that
If things work ... venture to hard disk.
o format a: /s /v .... bootable floppy
o copy /path/of/vmlinuz a:
o copy /path/of/loadlin.exe a:
o make a one line config.sys
shell=a:\loadlin.exe a:\vmlinuz root=/dev/hda2 ro
(change "root=" to the path your Linux is installed)
7.1.4 Can you boot Linux ? If yes, then proceed to make this
disk multi-boot.
7.2 Making new boot floppy to multi-boot
7.2.1 Copy msdos1.sys (from the one which you changed attrib)
to this disk.
o ren msdos1.sys msdos.sys
o attrib +h +r +s msdos.sys
7.2.2 Make a config.sys with only two options ... plain Win98
and Linux.
------------<Sample config.sys for boot disk>-----------
[menu]
menuitem=Menu1, Win-98
menuitem=Menu2, Linux
menudefault=Menu1,15
menucolor=15,1
[Menu1]
REM Default into Win-98 DOS mode
DEVICE=C:\windows\HIMEM.SYS /testmem:off
DEVICEHIGH=C:\windows\EMM386.EXE NOEMS
dos=HIGH,UMB
stacks=9,256
buffers=32,0
files=32
FCBS=4,0
[Menu2]
REM Load Linux through Config.sys
shell=a:\loadlin.exe a:\vmlinuz root=/dev/hda2 ro
---------------</End of Config.sys>---------------------
7.2.3 There may not be enough space on this disk for all the
files needed by Win ... so no need for putting autoexec
or putting additional drivers except for HIMEM.SYS and
EMM386.EXE on the floppy ... after all, this is for test
only.
7.2.4 Boot from this floppy. You will notice a menu of Win-98
and Linux on a blue screen. Select with arrow keys and
press [Return] to confirm.
7.2.5 This will give the confidence to play around more. When
you are cock sure ... take the plunge, and make changes
to your hard disk set up.
7.3 Setting it on your hard disk
7.3.1 DO NOT DELETE old Win9x Configuration files. Just rename
them to msdos.000, config.000 and autoexec.000. In case
of trouble, boot through Win rescue disk and rename the
.000 files. You would have to change attributes of
msdos.sys of-course before renaming!
7.3.1 Copy the msdos.sys file from the working a: boot disk to
c: ... the procedure is the same as above.
o C:\> attrib -r -h -s a:\msdos.sys
o C:\> copy a:\msdos.sys C:\
o attrib +r +h +s C:\msdos.sys
7.3.2 Write a config.sys for C: with all the parameters you
normally use for your Win-9x system. I am placing below
a config.sys with 2 Linuxes, Win-98 and DOS. The "pygmy"
linux is just to show how an UMSDOS installation is done
for a full installation on a M$ partition at /dev/hda1.
7.3.3 I am also placing an autoexec.bat below (Appendix "C").
Note how each segment calls a separate batch file. It is
easier to maintain and errors in one do not cascade over
to other batch processes.
7.3.4 I am also placing a linux.bat file (Appendix-"D") which
has been commented enough for your discomfort ;-) I am
assuming that you need no assistance in writing batch
files for Win and DOS ...
8 Loadlin and MS-DOS
8.1 Unlike in Win-9x, msdos.sys is NOT an ASCII file. There
is no scope of menu through config.sys, so loading has
to be through autoexec.bat only. This applies for all
versions of MS-DOS (ver 6.22 and below), DR DOS and all
other types of DOS.
8.2 There is a need to flush all unwritten buffers before
loadlin is called:
smartdrv /C
8.2.1 Reduce the number of devices installed through config.
sys. When loadlin loads the kernel it automatically
clears them all, but more time is taken.
8.3 For MS-DOS loadlin boots the changes from Win-9x are:
o no tinkering with msdos.sys (you cannot, binary file)
o no tinkering with config.sys
o only loading through autoexec.bat
9 How to make a Loadlin boot disk
9.1 The simplest method of making a boot disk is through
loadlin. Totally a MS-DOS (or DOS prompt) job:
o format a: /s /v
o copy c:\loadlin\loadlin.exe a:
o copy c:\loadlin\vmlinuz a:
o write a one line config.sys:
---
shell=a:\loadlin.exe a:\vmlinuz root=/dev/hda2 ro
REM (change "root=" to the path your Linux is installed)
---
9.2 Note, if you have loadlin installed, and you use it for
booting purposes, there is absolutely no need for LILO
or having anything in /boot. However, it is not a bad
idea keeping /boot and LILO, in case you want to switch
at a later date, or want to make a LILO based boot disk
Note: Programs like mkbootdisk need LILO ...
9.3 FYI, there is also a shell script written by me for the
making of LILO boot floppies available for download at:
http://oocities.com/usmbish/mbf-0.3.tar.gz
9.3.1 I don't want to write a batch file about making loadlin
boot disks ... the process is too simple ...
10 Some other handy utilities
10.1 Winux is a graphical configuration interface for Loadlin
bootloader. Once installed, it can also be used to fire
Linux from within Windows. This is a program written in
Delphi by Herve Utard, and is available under GPL from:
http://www.linux-france.org/prj/winux/English/Downloads.html
10.1.1 For this program to operate the kernel images would have
to be copied from the ext2 partition to the Windows par-
tition, by the method described earlier.
10.1.2 This program essentially creates a winux.conf file of
the Linux installations on your system, and can be fired
from your Windows desktop. The program clears all memory
before handing control to Linux.
10.1.3 In the method described by me earlier, we are going over
into Linux at the config.sys stage itself, so there is
no need to go into Windows at all. However, if you are
new to the game, and more comfortable from the Windows
screen, this is another option.
10.2 explore2fs : This is a must-have if you want to read (or
write to) ext2 partitions from Windows. The write option
as on date of this HDI was still experimental. This is a
program written in Delphi, by John Newbegin and is GPLed
It is available for download from:
http://uranus.it.swin.edu.au/~jn/linux/explore2fs.htm
10.2.1 WARNING: The write support is still experimental. There
are chances of damaging your file system... It is better
avoiding write to ext2 partitions at this stage. Default
"read only" support is safe for unrestricted use ... and
can be used for jobs like copying the kernel image from
your ext2 partition to M$ partition.
##############################################################
11 Appendices
##############################################################
Appendix - "A"
---------------[ MSDOS.SYS ]----------------------------
[Paths]
WinDir=C:\WINDOWS
WinBootDir=C:\WINDOWS
HostWinBootDrv=C
[Options]
BootMulti=1
BootGUI=1
DoubleBuffer=1
AutoScan=1
WinVer=4.10.2222
;
;The following lines are required for compatibility with other programs.
;Do not remove them (MSDOS.SYS needs to be >1024 bytes).
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxa
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxb
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxc
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxd
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxe
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxf
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxg
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxh
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxi
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxj
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxk
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxl
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxm
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxn
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxo
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxp
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxq
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxr
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxs
#######################################################################
Appendix - "B"
----------------[ CONFIG.SYS ]----------------------
[menu]
menuitem=Menu1, DOS Prompt (Win-98)
menuitem=Menu2, Slakware (Ver 7.1)
menuitem=Menu3, Pygmy Linux
menuitem=Menu4, Windows 98 Normal
menudefault=Menu1,15
menucolor=15,1
[Menu1]
REM Default into Win-98 DOS mode
REM Enable xms thru himem.sys (640-1024k)
DEVICE=C:\windows\HIMEM.SYS /testmem:off
REM Enable memory beyond 1 mb
DEVICEHIGH=C:\windows\EMM386.EXE NOEMS
REM Load DOS High in memory
dos=HIGH,UMB
REM CD-ROM Driver primer
DEVICEHIGH /L:1,40800 =C:\WINDOWS\OAKCDROM.SYS /D:MSCD001
REM Enable Compressed drive r & w
DEVICEHIGH=C:\WINDOWS\COMMAND\DRVSPACE.SYS /MOVE
REM Requirements of Win/ DOS software
stacks=9,256
buffers=32,0
files=32
FCBS=4,0
[Menu2]
REM Load Linux through Config.sys
rem It is possible to boot Linux from here as shown below
rem shell=c:\loadlin\loadlin.exe @C:\loadlin\linuxpar.1
rem ----------------------------------------------------
REM If the line below is commented, then we can load Linux
REM through AUTOEXEC.BAT but that option at times fails to
REM operate successfully
shell=c:\loadlin\loadlin.exe c:\loadlin\vmlinuz.slk root=/dev/hda2 ro
[Menu3]
REM Load Pygmy Linux through Config.sys
rem ----------------------------------------------------
REM Note attribute has to be ro for ext2 and rw for umsdos
REM ------------------------------------------------------
shell=c:\loadlin\loadlin.exe c:\loadlin\vmlinuz.pyg root=/dev/hda1 rw
[Menu4]
REM Load Windows-98 Normal, Same as DOS except that
REM CDROM driver NOT needed
DEVICE=C:\DOS\HIMEM.SYS
DEVICE=C:\DOS\EMM386.EXE NOEMS
DOS=HIGH, UMB
DEVICEHIGH=C:\WINDOWS\COMMAND\DRVSPACE.SYS /MOVE
DEVICEHIGH=C:\WINDOWS\setver.exe
buffers=32,0
files=32
dos=UMB
FCBS=4,0
################################################################
Appendix -"C"
-------------[ Autoexec.BAT ] ----------------------
@IF ERRORLEVEL 1 PAUSE
@ECHO OFF
IF "%config%"=="Menu1" GOTO Menu1-BAT
IF "%config%"=="Menu2" GOTO Menu2-BAT
IF "%config%"=="Menu3" GOTO Menu3-BAT
IF "%config%"=="Menu4" GOTO Menu4-BAT
:Menu4-BAT
REM This is in reverse order, with default last
REM This is for Windows-98 (item 4 on menu)
REM Control being passed to external program
command c:\command.com /k c:\util\Win98.bat
:Menu3-BAT
REM Load Linux (Pygmy) from UMSDOS partition
command c:\command.com /k c:\util\pygmy.bat
:Menu2-BAT
REM Load Linux (Slackware) from /dev/hda2
command c:\command.com /k c:\util\linux.bat
:Menu1-BAT
REM This is exactly same as Windows except for necessity for
REM loading mouse and CDROM device drivers
command c:\command.com /k c:\util\dos7.bat
###############################################################
Appendix - "D"
---------------[ c:\util\linux.bat ]----------------
@ECHO OFF
rem This loads Slackware Linux 7.1 from /dev/hda2
rem Loadlin <kernel_image> root=<root device> ro|rw
rem If on UMSDOS then "ro" should be changed to "rw"
rem Other information may need to be passed to the
rem kernel through Loadlin docs
rem
C:\loadlin\LOADLIN.EXE C:\loadlin\vmlinuz.slk root=/dev/hda2 ro
------------------------</end>---------------------
################################################################
12 Kudos and Brickbats
12.1 This document is released under GNU/ GPL license. You are
free to use and distribute this without any encumbrances.
12.2 Any kudos and brickbats should be directed at:
USM Bish <bish@nde.vsnl.net.in>
20 Sep 2001