[gentoo-embedded] Re: your very helpful embedded-gentoo howto and CF card

[Heath H Holcomb]

I would not use a 2.4 kernel unless your specific hardware is not stable on 
2.6 or you need a custom application that only runs under 2.4.  In either 
case these requirements are rare, and 2.6 is mostly the way to go.

On my development system I have a hard drive with a full install of Gentoo 
2005.0, and 1 GB partition setup so I can set up my embedded rootfs to test.  
I use the Gentoo install to mount a NFS shared directory from my development 
laptop (were I guild the embedded rootfs) and copy over the embedded rootfs 
to the 1 GB partition.  I then modify my gurb.conf to give me the option of 
booting from the embedded rootfs on the 1 GB partition.  This speeds 
development because getting the embedded rootfs done write the first time is 
almost impossible.

The problem sounds like a kernel thing.  Move to 2.6 and then see what 
happens.  Remember lspci is your friend (to find out what hardware you have).

Also remember Compact Flash cards have limited writes to the flash cells 
(usually measured in 100,000 to 300,000 writes); while hard drive have writes 
measured in hundreds of millions or billions.

Your board uses the CLE266.  If you want X (not using the generic vesa driver) 
you need to look at the Unichrome project.  I subscribe to there mailing 
list.
http://unichrome.sourceforge.net/

I'm also sending this response to the mailing list.

I'm deploying my embedded rootfs to my test hard drive this weekend, so I'll 
have corrections and modifications to the how-to.  By the end of the weekend 
the x86 how-to should be somewhat complete, at least at a very basic level.

-- 
Heath Holcomb
liquidcable
liquidcable at bulah.com


On Friday 03 June 2005 01:39 pm, you wrote:
> Hi Heath,
>
> As you may recall, I was going to try to use your HOWTO to
> create a gentoo embedded system on a CF card. I followed your
> instructions up to Step 6, and then I do the following. I'm
> not booting yet. Grub starts, but then seems to crash when
> the kernel starts. I'm not sure because it's on the screen for
> a split second and then my machine reboots. I suspect that I
> made some mistakes in the kernel so I'm going to rebuild it,
> and try again, but if you have any comments or thoughts on my
> process I welcome them:
>
> My target SBC is a VIA EPIA ME-6000. I have my CF card as
> my primary IDE device, and a CDROM drive as the secondary IDE device.
> In the CDROM I'm using the Gentoo 2005.0 live cd.
>
> I'm sending this to you alone because I don't know if it's of
> general enough interest. If you think it is, please feel free
> to send it to the gentoo-embedded list, or tell me and I'll do it.
>
> The mistake I think I made in the kernel is that I built it on an old
> gentoo system with a 2.4 kernel, so it created a 2.4 kernel, but your
> instructions seem to be for a 2.6, so I'm going to repeat the process on
> a newer gentoo system with a 2.6 kernel.
>
> Any comments are welcome
>
> Thanks again for writing your HOWTO
>
> Michael
>
> ---
>
>
> 1. attach CF card as primary, CDROM as secondary
>
> 2. boot Gentoo live CD
>
> 3. fdisk /dev/hda
>
>    boot: hda1 32M ext2 type 83
>    root: hda2 rest ext2 type 83
> remember to make hda1 bootable
>
> 4.
>    mke2fs /dev/hda1
>    mke2fs /dev/hda2
>
> 5. mount the root and boot partitions
>
>    mkdir /mnt/hda1
>    mount -t ext2 /dev/hda1 /mnt/hda1
>    mkdir /mnt/hda2
>    mount -t ext2 /dev/hda2 /mnt/hda2
>
> 6. copy the developed rootfs into the second partition on the CF card
>
>      # on devel machine in chroot env
>      cp -r /embedded_rootfs /tmp # first copy from chroot env to outside
> world
>
>      # on devel machine in normal env
>      scp -r /opt/i586-gentoo-uclibc-linux/tmp/embedded_rootfs \
>       root@192.168.0.22:/mnt/hda2    # IP address of my target SBC
>      FIXME do something about buzybox links
>      FIXME some problem with portage - same?
>
> 7. copy grub
>
>      # on devel machine in normal env
>      scp /sbin/grub root@192.168.0.22:/mnt/hda2
>
> 8. copy boot dir to /boot
>
>    on target SBC
>      cp -r /mnt/hda2/boot/* /mnt/hda1
>
> 8. install grub
>
>    % /mnt/hda2/grub
>
>    root (hd0,0)  # grub's root i.e. boot
>    setup (hd0)
>    quit
>
> 9. configure grub.conf
>
>    % nano -w /mnt/hda1/grub/grub.conf
>
>      default 0
>      timeout 10
>      splashimage=(hd0,0)/grub/splash.xpm.gz
>
>      title=Linux 2.6.x
>      root (hd0,0)
>      kernel /vmlinuz-2.6.x root=/dev/hda1
>
> 10. fstab
>
>    % nano -w /mnt/hda2/etc/fstab
>
>    # <fs>          <mountpoint>    <type>          <opts>    <dump/pass>
>    none                    /proc           proc            defaults
> 0 0
>
>    # glibc 2.2 and above expects tmpfs to be mounted at /dev/shm for
>    # POSIX shared memory (shm_open, shm_unlink).
>    # (tmpfs is a dynamically expandable/shrinkable ramdisk, and will
>    #  use almost no memory if not populated with files)
>    # Adding the following line to /etc/fstab should take care of this:
>
>    none                    /dev/shm        tmpfs           defaults
> 0 0 /dev/hda2       /               ext2            ro        0 1
>
>
> 11. reboot
>
>    sync    # make sure writes are flushed to CF card
>    reboot

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