Re: [gentoo-embedded] baselayout-2, busybox and uclibc

[Natanael Copa]

On Wed, 2007-10-10 at 20:48 +0200, Marc Blumentritt wrote:
> Hi,
>
> first: Be warned, this is a long email!
>
> I'm working on my first embedded system. I plan to build for my media pc
>  a minimal gentoo, based on uclibc, busybox, and baselayout-2. I want to
> use standard init.d scripts from gentoo. The root file system will be
> placed in initramfs for maximum boot speed. Kernel will be monolithic
> and device files static.

interesting!

...

> QUESTION: Are there any useful configuration tips for dropbear?

default dropbear config have just worked for me.

> OK, the next steps are what I want to do next:
>
>
> 6.) Configuration of busybox: busybox provides a lot of tools, but some
> tools should not be used. I have so far identified:
> - start-stop-daemon (provided by baselayout-2)

I use bb start-stop-daemon (not with baselayout-2 though). It works for
almost all Gentoo scripts. (postgresql is one who does not)

> - init (provided by sysvinit)
> I configure busybox to not provide these tools in
> $PORTAGE_CONFIGROOT/etc/portage/savedefaults/sys-apps/busybox-1.6.1:
> Comment the following:
> # for start-stop-daemon
> CONFIG_START_STOP_DAEMON=y
> CONFIG_FEATURE_START_STOP_DAEMON_FANCY=y
> CONFIG_FEATURE_START_STOP_DAEMON_LONG_OPTIONS=y
> # for init
> CONFIG_INIT=y
> # CONFIG_DEBUG_INIT is not set
> CONFIG_FEATURE_USE_INITTAB=y
> CONFIG_FEATURE_INIT_SCTTY=y
> CONFIG_FEATURE_INIT_SYSLOG=y
> CONFIG_FEATURE_EXTRA_QUIET=y
> CONFIG_FEATURE_INIT_COREDUMPS=y
> CONFIG_FEATURE_INITRD=y
> After configuration reinstall busybox with USE=savedconfig
>
> QUESTION: Are there any tools I should disable, too? Do I really need
> coreutils (and ncurses, which is pulled in by coreutils) or are the
> busybox tools enough (busybox provides about 69% of the tools in coreutils)?

I think busybox coreutils should work.  If it doesn not, we should fix
busybox. (if you give me a list, I can take a look at it when i get
time)

Here below you also say you use sysvinit. Then you can turn off bb init
i think. (unless you use it in initramfs)

> 7.) Device files: create minimum device file set. QUESTION: What is the
> minimum device file set for booting in ram from initramfs? The following
> list is taken from "Building Embedded Linux Systems":
> files:
> mem, null, zero, random, tty0, tty1, ttyS0 (QUESTION: do I need this? I
> do not want to use a serial port), tty, console
> links:
> fd (link to /proc/self/fd), stdin (link to fd/0), stdout (link to fd/1),
> stderr (link to fd/2)
>
> Are there any other files?

why not just run mdev -s and let mdev create everything.

> All files I need to fully use my media-pc I will create after booting
> with mdev (from busybox) and copy them to my build machine, since I want
> to use static device files.

You might want to have a look at my medv config and /lib/mdev/* scripts
shipped in my alpine-baselayout.

http://dev.alpinelinux.org/alpine/alpine-baselayout/

I have also an init.d/mdev script that let me use mdev as an udev
replacement.

> 8.) System configuration: up to now I have only two QUESTIONs:
> -How do I use locals with uclibc?

You mean locales? uclibc has locale support but its not good :-(

> -Do I have to tell baselayout-2, that I use ash as shell?

I dunno, I think /bin/sh pointing to busybox should be enough.

> 9.) install grub.
>
> 10.) Build kernel and initramfs from ROOT
>
> 11.) Boot media-pc with livecd and copy kernel, initramfs and grub files
> to media-pc. QUESTION: Since I have already grub installed on my
> media-pc, grub installation to boot sector is not a problem, but what do
> you do, if you do not have grub installed? Boot with livecd, extract
> initramfs and use installed grub to install grub to boot sector?

You can use grub on livecd.

>
> QUESTION: Do you have any remarks?

You could try busybox-1.7.x. Its a good release.

>
> OK, thanks for reading.

Thanks for sharing your experiences

> Marc

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