[Toybox] Booting a toybox system

[Rob Landley]

On 12/21/13 23:26, ibid.ag at gmail.com wrote:
> I did some testing on what it took to get a minimal toybox system to boot,
> autoload modules, and connect to the network (manually).

I've fiddled around with this before but it's a judgement call: all you 
need to boot a system to a shell prompt via initramfs is a shell. What 
the system needs depends entirely on what it'll be doing.

The aboriginal use case in the roadmap includes what aboriginal needs, 
but among other things that don't use modules...

> I'm testing in qemu with user networking; the ethernet drivers are built
> as modules (pcnet32.ko/e1000.ko).
>
> Instead of building a root filesystem, I'm just using the initrd as a
> live filesystem.

The initmpfs patches were intended to make this a bit easier. I need to 
go do some more work on aboriginal to make it default to a basic system 
in initmpfs and then mount the toolchain on a directory and properly set 
it up in the $PATH, add some symlinks, and maybe a bind mount or two... 
But given how little time I've been able to scrape up for toybox lately, 
trying to carve off more for aboriginal is... a todo item.

> I create bin/, dev/, proc/, sys/, var/run/, var/log/, lib/modules/, lib/dhcp/,
> tmp/, and mnt/. sbin can be a symlink to bin.
> toybox gets dropped in bin/ and all the necessary symlinks created.

Ok.

> Modules get installed in /lib/modules/$KERNRELEASE/kernel/, as they would
> ordinarily; I then run in the project root:
> /sbin/depmod -b . $KERNRELEASE
> rm lib/modules/*/*.bin lib/modules/modules.{softdep,devname}
> #extract any files I need
> #create the initrd:
> find ./|cpio -o -H newc |gzip -9c >../tbinitrd.img
>
> And that's ready for qemu.
>
>
> In qemu, I configure the network like so:
> ifconfig eth0 up
> dhcp -v -s /lib/dhcp/set.sh
>
> Hope this is helpful to someone,

Sounds good. So what's the prognosis, anything majore missing? (You used 
depmod and toybox hasn't got one, but is that a build tool or a runtime 
tool...)

> Isaac Dunham
>
>
> Commands needed:
> Other programs:
> pdksh (as /bin/sh)

I really need to find time to tackle toysh properly. I know what I need 
to _do_, I'm just having to stay more fully employed to support my 
family than I did a few years back...

>>From toybox:
> #boot
> init
> mount # hacked version of Ashwini Sharma's last version; all probably work
> mkdir # for /dev/pts
> getty # I used mine
> login # if you use pdksh directly, you don't need getty or login
>
> #autoload modules; no, the kernel doesn't seem to do this...
> find
> cat
> xargs
> resolve_modalias # mine; because modprobe -q isn't quiet (optional)
> modprobe         #v2 from Ashwini

Is that a bug in modprobe?

> #networking
> ifconfig
> dhcp
> route
>
> #testing
> ftpget  # from Ashwini with my patch, to test network
> echo
> env
> ls
> lsmod
>
> #shutdown
> sync
> umount
> kill
> killall
> poweroff # optional if you send the right signal to init
>
> Scripts:
>
> /init: (devtmpfs is not automounted from the initrd!)

I need to send another kernel patch to make the devtmpfs automount thing 
actually happen for initmpfs...

> #!/bin/sh
> mount -t devtmpfs dev /dev
> exec toybox init
>
> /etc/fstab (simplifies rcS)
> /etc/inittab (not needed with Ashwini's getty)
> /etc/init.d/rcS (autostart at boot)
> /lib/dhcp/set.sh
>
> Files for user accounts...
> /etc/passwd
> /etc/shadow
> /etc/group
> /etc/profile

Looks good to me. I might be up for adding a www/rootfs directory with 
an example root filesystem layout. (It would logically be doc/skeleton 
but our documentation directory is a copy of the website, so...)

Or maybe ascript to generate such (via here documents) would make more 
sense, living in scripts?

Thanks for the heads up,

Rob

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