RE: [gentoo-embedded] x86 SBC Gentoo Embedded HotTo version 0.07

[Marcel Romijn]

Hi Heath,

I know about the limited number of write cycles on CF. Therefore I want
the CF only to supply the kernel and the ramdisk image. My intention is
to run Linux and my application completely from ramdisk.
I want my device to be complately silent, therefore it has a fanless
ME6000 board, no fans in the case and no harddisk (actually strange to
'hear' a computer boot in complete silence!). The CF is on an IDE
converter and is recognized as /dev/hda1 (although for testing it has a
normal harddisk connected).

I was able to follow your howto to the end.
Although I had some problems where the boot process stopped after
"Freeing unused kernel memory". This turned out to be a typo in
/etc/fstab on my side.

Now that I have bootable configuration, I can look into what it takes to
have the system files in a ramdisk image and have it mounted as '/'.

I think I could just create an initrd from the whole system and have
grub and the kernel extract it in memory and mount it.
I have not done much investigation on it, be it seems to me that the
/linuxrc in the initrd can be fairly simple. Actually just calling the
/sbin/init once the ramdisk is mountded as '/'.

Anyone any experience with this?

PS. Maybe we should spawn of another thread about VIA Epia boards, CF
and booting. I saw Pierre Cassimans is interested in this subject as
well.
This might go off topic for the Gentoo Embedded Howto.

Marcel

-----Original Message-----
From: Heath Holcomb [mailto:liquidcable@×××××.com] 
Sent: Sunday, 14 August, 2005 0:53
To: gentoo-embedded@l.g.o
Subject: Re: [gentoo-embedded] x86 SBC Gentoo Embedded HotTo version
0.07

On Friday 12 August 2005 01:39 am, Marcel Romijn wrote:
> Hello Heath,
>
> Nice writedown! I haven't made it to the end yet (lack of time), but
I'm
> getting there...
>
> I noticed some issues along the way (not counting grub begin spelled
as
> "grug" or "gurb" ;-) )
>
> In step 3 you write:
>
> <snip>
> # Set root password for the embedded_rootfs
> chromm /embedded_rootfs
> passwd
> rm /embedded_rootfs/etc/passwd-
> Exit
> </snip>
>
> I presume 'chromm' should have been 'chroot' ?
> If it is indeed 'chroot' then you should either do "rm /etc/passwd-"
> before the "exit" or the "exit" before the "rm
> /embedded_rootfs/etc/passwd-".

Yes, "chromm" should be "chroot".  The order is correct, as far as I can
tell.
chroot /embedded_rootfs
passwd
rm /embedded_rootfs/etc/passwd-
exit


> A few lines down, you write:
>
> <snip>
> rm -R /embedded_rootfs/var/db/pkg/ *
> </snip>
>
> As a reletive newbie, doing a quick copy/paste of this command late in
> the evening as root in '/', this wiped out all files, except the ones
> that were firmly locked.
> Fortunately, I'm going through you HowTo in VMWare, so I could restore
a
> previous snapshot ;-)
>
> I presume the space before the '*' should have been omitted?
>
> <snip>
> rm -R /embedded_rootfs/var/db/pkg/*
> </snip>

Major typo on my part.  Fixed in version 0.08.

>
> My aim is to create an embedded Gentoo for a Via Epia ME6000, which
> reads the kernel and a ramdisk image from CF and then runs completely
> from RAM.
> If I'm not mistaken, you were heading for a Via Epia as well?

My target will be a Via based SBC.  From what I have read using a
ramdisk on a 
x86 based platform really does not buy you much.  But you sure don't
want to 
write to the CF all that often (limited write cycles, usallay 100,000 to

300,000).  So I plan on mounting the / partition of the CF as read only
and 
creating a separate partition that is mounted read/write and have my
embedded 
application and only my application write to that partition.

> Regards,
>
> Marcel Romijn
>
>
> -----Original Message-----
> From: Heath Holcomb [mailto:liquidcable@×××××.com]
> Sent: Monday, 08 August, 2005 4:17
> To: gentoo-embedded@l.g.o
> Subject: [gentoo-embedded] x86 SBC Gentoo Embedded HotTo version 0.07
>
> Version 0.07
> Please add, delete, modify. Thanks!
>
> Several fixes.  Root password now works.  Several work arounds are no
> longer
> need, as the embedded Gentoo team has fixed them (I'm guess because I
no
>
> longer get those errors).  There is still one problem when "emerge -e
> system"
> for groff.  Bug 98187 (http://bugs.gentoo.org/show_bug.cgi?id=98187).
> Check
> out the bug report for the temp fix/work around (USE="-sandbox" emerge
> -e
> system).
>
> I've update my website with this version also.
> http://www.bulah.com/embeddedgentoo.html
>
>
>
#-----------------------------------------------------------------------
> ---------
> # Embedded Gentoo How-To for x86
> #
> # A how-to guide to setup a Gentoo embedded environment, you must be
> root.
> # These commands are to be run on your development system,
> # any x86 Gentoo Linux computer will do.  The system should be fast,
> # to speed development.  The target can be any x86 based SBC.  I'm
> # using a Geode based SBC.  Latter I'll use a Via based SBC.
> #
> # version 0.07
> # 2005.8.7
> #
> # Heath Holcomb (heath at bulah.com)
> # Ned Ludd (original commands posted)
> # Lloyd Sargent (contributor)
> # Yuri Vasilevski (contributor)
> # Mike George (contributor)
> # Kammi Cazze (contributor)
> # Marius Schaefer (contributor)
> #
> # Definitions and Terms
> # system_rootfs = your regular rootfs, development computer
> # development_rootfs = what you use to build the embedded_rootfs
> # embedded_rootfs = rootfs you deploy to the target system
> # SBC = single board computer (here it's an x86 based)
> #
> # References
> # http://www.gentoo.org/doc/en/handbook/index.xml
> # http://www.epiawiki.org
> # http://epia.kalf.org
> # Gentoo embedded mailing list (gentoo-embedded@l.g.o)
> #
> #
> # Overview of process (steps)
> # 1 - Prepare the development_rootfs from your system_rootfs
> # 2 - Build the development_rootfs
> # 3 - Build the embedded_rootfs
> # 4 - Build and install non-system programs to the embedded_rootfs
> # 5 - Build and install a kernel to the embedded_rootfs
> # 6 - Deploy embedded_rootfs to target
> #
>
#-----------------------------------------------------------------------
> ---------
>
> #----- Step 1 - Prepare the development_rootfs from your system_rootfs
> -------
>
> # You must be root.
> su -
>
> # Create the development_rootfs.
> # I use i586 because of target is a Geode processor.
> mkdir -p /opt/i586-gentoo-uclibc-linux/usr/portage
>
> # Download the latest stage 1 tarball.
> wget \
>
http://gentoo.osuosl.org/experimental/x86/embedded/stages/stage1-x86-ucl
> ibc-2005.0.tar.bz2
>
> # Untar the stage to the development_rootfs.
> tar -xvjpf stage1-x86-uclibc-2005.0.tar.bz2 -C
> /opt/i586-gentoo-uclibc-linux/
>
> # Mount the proc and portage directories to your development_rootfs.
> # Makes your system_rootfs's proc and portage directory available from
> inside
> # of your development_rootfs (after chrooting).
> mount --bind /proc /opt/i586-gentoo-uclibc-linux/proc/
> mount --bind /usr/portage /opt/i586-gentoo-uclibc-linux/usr/portage
>
> # Copy over DNS information to the development_rootfs.
> cp /etc/resolv.conf /opt/i586-gentoo-uclibc-linux/etc/resolv.conf
>
> # Chroot into the development_rootfs.
> chroot /opt/i586-gentoo-uclibc-linux /bin/bash --login
>
>
> #----- Step 2 - Build the development_rootfs
> ---------------------------------
>
> # Create new environment and load variables into memory.
> env-update
> source /etc/profile
>
> # Modify make.conf file to your liking/needs.
> nano -w /etc/make.conf
> # This is for my target, Geode x86 processor.
> /*
> USE="bitmap-fonts minimal truetype-fonts mmx"
> CHOST="i586-gentoo-linux-uclibc"
> CFLAGS="-march=i586 -Os -pipe -fomit-frame-pointer -mmmx"
> CXXFLAGS="${CFLAGS}"
> FEATURES="buildpkg"
>
> VIDEO_CARDS="chips"
> UCLIBC_CPU="586MMX"
> */
>
> # Set profile to use 2.6 kernel.
> # The current stage uses 2.4 by default, and for most cases you are
> going
> # to want a 2.6.x kernel.
> cd /etc/
> unlink make.profile
> ln -s ../usr/portage/profiles/uclibc/x86 make.profile
>
> # Start the bootstrap script.
> cd /usr/portage/scripts
> ./bootstrap.sh -p -v
> ./bootstrap.sh
>
> # Emerge the system ebuild for the development_rootfs.
> emerge -e system
>
> #----- Step 3 - Build the embedded_rootfs
> ------------------------------------
>
> # Create the embedded_rootfs directory.
> mkdir /embedded_rootfs
>
> # Emerge baselayout-lite into embedded_rootfs.
> # This gives your system a basic file structure.
> # 1.0_pre1 is the only one that is stable, right?
> cd /usr/portage/sys-apps/baselayout-lite/
> ROOT=/embedded_rootfs emerge baselayout-lite-1.0_pre1.ebuild
>
> # Workaround 1
> # Baselayout-lite is still beta, so a few fixes are needed.
> # There needs to be a directory "log" in /var.
> # Inittab calls for /usr/bin/tail, but it needs to /usr/bin.
> mkdir /embedded_rootfs/var/log
> nano -w /embedded_rootfs/etc/inittab
> /*
> #tty3::respawn:/usr/bin/tail -f /var/log/messages
> tty3::respawn:/bin/tail -f /var/log/messages
> */
>
> # Emerge uclibc into the embedded_rootfs.
> # Use the -K option because we don't get the extra files created by
the
> # build/emerge process into our embedded rootfs which needs to be as
> # small as possible.
> ROOT=/embedded_rootfs emerge -K uclibc
>
> # Emerge busybox into the embedded_rootfs.
> # First you must emerge it into your development_rootfs.
> # This does not create the symlinks in our development embedded
rootfs.
> emerge busybox
> ROOT=/embedded_rootfs emerge -K busybox
>
> # Create the symlinks for busybox in the embedded_rootfs.
> mkdir /embedded_rootfs/proc
> mount -o bind /proc/ /embedded_rootfs/proc/
> chroot /embedded_rootfs /bin/busybox --install -s
> umount /embedded_rootfs/proc
>
> # Set time zone in your embedded_rootfs.
> # See http://leaf.sourceforge.net/doc/guide/buci-tz.html for details.
> # For central standard time in the US, use "CST6CDT".
> nano -w /embedded_rootfs/etc/TZ
> /*
> CST6CDT
> */
>
> # Install a boot loader (usually grug or lilo).
> # Once you copy/deploy your embedded_rootfs to your target SBC you
will
> # have to run grub on the command line to write to the master boot
> record
> # (MBR).
> # For some reason not all of /boot/grub is copied over to the
> # embedded_rootfs, so a extra manual copy step is needed.
> # The --nodeps gets rip of the run time need of ncurses.
> emerge --nodeps grub
> ROOT=/embedded_rootfs emerge -K --nodeps grub
> cp -R /boot/grub /embedded_rootfs/boot/
>
> # Modify your boot configure file.
> # The example below is for a gurb, for a boot partition on /dev/hda1
and
> only
> # one partition on the target SBC system.
> nano -w /embedded_rootfs/boot/grub/grub.conf
> /*
> default 0
> timeout 10
> splashimage=(hd0,0)/boot/grub/splash.xpm.gz
>
> title=Linux 2.6.x
> root (hd0,0)
> kernel /vmlinuz-2.6.x root=/dev/hda1 vga=792
> */
>
> # Set root password for the embedded_rootfs
> chromm /embedded_rootfs
> passwd
> rm /embedded_rootfs/etc/passwd-
> exit
>
> # Modify fstab.
> # Below is mine, yours may vary.
> nano -w /embedded_rootfs/etc/fstab
> /*
> /dev/hda1		/		reiserfs	defaults
> 0 0
> none			/proc		proc		defaults
> 0 0
> none			/sys		sysfs		defaults
> 0 0
> none			/dev/shm	tmpfs	defaults	0 0
> */
>
> # Clean up the embedded_rootfs.
> # Don't know why these files are there in the first place, so if
anyone
> # can tell me why.....
> rm -R /embedded_rootfs/var/db/pkg/ *
> rm -R /embedded_rootfs/var/lib/portage/
>
> #---- Step 4 - Build and install non-system programs to the
> embedded_rootfs --
>
> # Emerge other software you need for you embedded target.
> # This is very wildly depending on your needs.
> # Also your proprietary application will be done here.
> emerge foo*
> ROOT=/embedded_rootfs emerge -K foo*
>
>
> #---- Step 5 - Build and install a kernel to the embedded_rootfs
> -------------
>
> # Install a kernel into embedded_rootfs.
> # First we will emerge it into our development_rootfs, then configure
> and
> # build it.
> emerge vanilla-sources
> cd /usr/src/
> cd linux
> make menuconfig
> # Configure your kernel for your TARGET SBC here.  I HIGHLY suggest
you
> # configure the kernel to compile everything into the kernel, and
> nothing
> # as a module.
> make
> ROOT=/embedded_rootfs make modules_install
> cp /usr/src/linux/arch/i386/boot/bzImage
> /embedded_rootfs/boot/vmlinuz-2.6.x
>
> # A few notes on compiling your kernel.
> # If deploying to Compact Flash/DiskOnChip/SD use ext2, as the
> journaling
> # filing systems "write" to much for a flash device.
> # If deploying to a hard drive use a journaling filing system, such as
> # ext3 or reiserfs.
>
>
> #---- Step 6 - Deploy embedded_rootfs to target
> ------------------------------
>
> # Prepare a Gentoo (or any Linux distro) system on the target SBC
using
> a
> # harddrive.  This is known as the target development rootfs.
> # We will create a partition (/embedded_rootfs) that will server as
our
> # "test" partition to deploy our embedded_rootfs that we generate on
our
> # development_system.
> #
> # I use the following partitions to speed development (yours may
vary):
> # /dev/hda1 - /embedded_rootfs - 1 GB
> # /dev/hda2 - /boot - 100 MB
> # /dev/hda3 - swap - (size varies, 512 MB is a good number)
> # /dev/hda4 - / - (what is left, at least 1.5 GB per 2005.0 install
> guide
> specs)
> #
> # Copy over your embedded_rootfs from you development system to your
> target
> # system and the directory /embedded_rootfs.  This needs to be done
via
> NFS as
> # need to preserve the permissions.
> #
> #The following commands are done from the
> # target development rootfs.
> mount -t reiserfs /dev/hda1 /mnt/embedded_rootfs
> mount -t nfs\
> 192.168.0.10:/opt/i586-gentoo-uclibc-linux/embedded_rootfs\
> /mnt/nfs_embedded_rootfs
> cp -adpR /mnt/nfs_embedded_rootfs/* /mnt/embedded_rootfs
>
>
> # Modify your target system's gurb.conf (or lilo.conf) for allow you
to
> boot
> # to the embedded_rootfs partition.
> #
> # Reboot, and if all goes well you'll be greeted with a login prompt.
> #
> # Fin.
>
>
>
> --
> heath holcomb
> liquidcable at bulah.com
> www.bulah.com
> --
> gentoo-embedded@g.o mailing list

-- 
heath holcomb
liquidcable at bulah.com
www.bulah.com
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