Bom is a micro kernel that makes extensive use of virtual file systems.
Currently the beagle bone black is the only device Bom runs on. It has support for UART, sd cards, mmc cards, timers, interrupts, etc. Currently no networking, USB, or HDMI.
To build for the beagle bone black run
make config_am335x
make
This will compile the kernel, libraries and utilities. You will then need to set up an sd card and copy them to it with utilities under /bin, and the kernel somewhere. You will probably want to copy u-boot's MLO and u-boot.img files along with a uenv.txt file. Or you can download a raw image of the file system with the kernel and utilities at some point in the recent past from here.
Once Bom boots you will be presented with something like
Bom Booting...
root:
message about a device...
message about a device...
message about a device...
Where 'message about a device...' will be one of 'sd card on mmc0' or 'emmc card on mmc1'.
From here if you enter '/dev/mmc0/a' bom will load the fat partition I (and you, not bom, but bom will believe you assuming partition 0 is active) assume exists on mbr partition 0 of the sd card and mount it on '/mnt'. Bom will then bind '/mnt/bin' to '/bin' and exec '/bin/init'.
'/bin/init' is whatever program you want the start on boot. I have a shell, also under '/bin/shell'. Surprisingly it is the shell in 'bin/shell' of this repository.
This shell is currently pretty flimsy. Horribly built too. So far it doesn't support pattern matching but does support list joining. If that is a term. For example I can do:
The shell has been rebuild. It is a lot better now but doesn't
support the following just yet. It does support {command grouping; like this} and conditionalls && like || this, along with
redirection.
% ls /bin/mount^(fat tmp)
11 25292 26624 /bin/mountfat
11 15224 16384 /bin/mounttmp
%
% ls /dev/mmc^(0 1)
dev/mmc0:
11 2934964224 2934964224 raw
11 67108864 67108864 a
dev/mmc1:
11 3925868544 3925868544 raw
11 16777216 16777216 a
11 3909058560 3909058560 d
%
Which makes things a little easier.
It supports redirections such as '>', '>>', '<', and pipes. Along with and's and or's. So this (should) work:
% mkdir /b
% mounttmp /b || echo mount failed. && exit
% echo hello > /b/test
% cat /b/test
hello
% echo hi there > /b/test
% cat /b/test
hi there
% echo go away >> /b/test
% cat /b/test
hi there
go away
%
And so on.
Ports, feature additions and criticisms all welcome.