Thomas Frasher schrieb:
> Has anyone out there placed the miniRTL on a compact flash and gotten it to
> boot.
>
I attached a text, that I've written sometimes in the past, as I had the same
problems:
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Hi out there,
due to some questions here in the past I wrote down my methode how I got along
with booting a harddiskless computer. The 'initrd' (init ramdisk) is in fact a
zipped
file containing a bitmap of a complete filesystem, eg ext2, with all the
standard paths and files. In general, you can zip '/' with all files and
directories to get such a
initrd. The problem is, of course, that it's much to big this way. So it's the
magic to reduce it by concentrate to the really needed files, which is
application specific. By
the way, on the CDs of the Suse Linux Distribution are some emergency
filesystems as initrd which should work as a base. I myself need the initrd to
boot a small
card-pc which is controlling a machine. So I format a normal ramdisk for
example with mke2fs and make a standard dir tree, which I need for my
application, e.g.:
/
/bin
/sbin
/usr
/usr/bin
/usr/sbin
/dev
/proc
/etc
/lib
and so on, the files therein result from your application. At me there are in
general network tools, login, shells, telnet and ftp-server and my
appilication. Tricky is the
choosing of the needed lib files, because some programs give misleading error
messages. (for example says ping: unknown protocol icmp, when a special lib
file is
missing.) Hint: load not working programs to an editor an search for "lib". So
you should get all needed lib file names easily. Is the contens of your
filesystem fixed (it
ouly needs the necessary files for running, so no kernel files, no '/boot'
directory etc), zip it with gzip to a file named initrd.img.gz or so. After
that you heads to your
destination drive. For me it's a IDE-Flash-Disk (so there are no special
drivers necessary like for DiskOnChip), but this should work for floppys also,
you just don't
have so much space... I made a script for that, on which I can explain the
steps best: All my files are under /rdisk, what has to be taken care of in the
relative
pathnames. This is necessary to make lilo working on this files and not on your
regular harddisk files for booting your desktop machine.
Script: "mkflash":
#cfdisk #make a partition an make it bootable (only for flash disks)
mke2fs -m0 /dev/hda1 #make ext2 filesystem
mount /dev/hda1 ./mnt #mount flash to /rdisk/mnt
cp -av ./boot ./mnt #copy boot folder with files
cp -av ./initrd.img.gz ./mnt #copy initrd image
echo
echo "lilo with ./etc/lilo.conf!"
./makelilo #install kernel+initrd
umount ./mnt
Well: the boot folder, needed by lilo, is written to the formatted and mounted
disk. In the folder has to be the kernel for your destination system, the map
file and the
bootsector boot.b, which you can copy from the /boot dir from your desktop
machine. It's important, that the kernel was compiled with initrd support!
(make
menuconfig in /usr/src/linux and then make dep clean zImage). After that also
our initrd.img.gz is copied to the disk. In the end, lilo is called with a
command line that
is in a own script "makelilo" for historical reasons:
lilo -r /rdisk -C /etc/lilo.conf
The parameters are a little bit doubled, but better keep on the safe side. They
tell lilo to read it's config file from /rdisk/etc/headlilo.conf where the
parameters for my
embedded pc are. Normally it would take /etc/lilo.conf by default, what would
giva a mess. The configuration file looks like this:
# LILO config file
# Start LILO global Section
boot=/dev/hda #boote from flashdisk
map=/mnt/boot/map #here's the mapfile for the Kernel: Attention Flashdisc
must still be mounted
install=/mnt/boot/boot.b #here's the bootsector
read-only #mount the initrd readonly
vga = normal # force sane state
verbose = 3 #tell what you do
#prompt
delay=25 #wait for some useraction
# End LILO global section
#
# Linux bootable partition config begins
append="initrd=initrd.img.gz" #tell the kernel that is has a initrd
#append="initrd=initrd.img.gz init=/bin/sh" #this way a shell is started
after booting, good for debugging the boot sequence
image = /mnt/boot/kernel #here's the Kernel
initrd= /mnt/initrd.img.gz #here's the initrd
root = /dev/ram #mount the ramdisk as rootfilesystem
label = Linux #that's the name of our system
ramdisk= 10240 #this is the size of my unzipped ramdisk in kbytes
# Linux bootable partition config ends
#
#
Okay, this way a PC should boot a linux and work just as normal, only that the
system is on a ramdisk. It's especially good for embedded systems, because
after a
power loss the machine is booting just normal (without checking the filesystem)
and is back to work in some seconds.
best regards
Bernd Stahlbock
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