In my previous post I noted I’m working on a project here in Los Angeles, of which I don’t wan to get much into the details of. On the other hand, what I’m going to tell you about this, for now, is that it’s a device and it’s running Gentoo as part of its firmware.
You can also guess, if you know us, that since both me and Luca are involved, there is some kind of multimedia work going on.
I came here to strip down as much as possible the production firmware so that the image could be as small as possible, and still allow all the features we need on the device. This is not a new task for me, as I’ve done my best to strip down my own router so that it would require the least amount of space as possible, and I’ve also done some embedded firmwares based on Gentoo before.
The first obstacle you have if you want to reduce the size of Gentoo is almost certainly the set of init scripts that come with OpenRC; for a number of reasons, the init scripts for things like
hwclock are not installed by the package that install the commands (respectively
sys-apps/util-linux) but rather are installed by OpenRC itself. They are also both enabled by default, which is okay for a general desktop system but fails badly on embedded systems, especially when they don’t even have a clock.
Then you have to deal with the insane amount of packages that form our base system; without going into the details of having
tar and so on as part of the base untouchable system (which luckily is much easier to override with the new Portage 2.2, even if it insists bothering you about an overridden system set), and focusing on what you’re going to use to boot the system, OpenRC is currently requiring you a mixture of packages including
which (a single command that lies in its own package … for ESR’s sake, why was it not implemented within coreutils yet?),
sed (seriously, four packages for these? I mean I know they are more widely used than
coreutils, as they are often used on non-Linux operating systems, but do they really deserve their own package, each of them?).
The most irritating part nowadays for me I guess is the
procps battle: with the latter now maintained by Debian, I wonder why they haven’t merged the former yet. Given that they are implementing utilities for the same areas of the system… of course one could wonder why they are not all part of
util-linux anyway — yes I know that Debian is also supporting GNU/kFreeBSD on their package. At any rate there is another consideration to be made: only the newer
procps allows you to drop support for the
ncurses library, earlier depended on it forcefully, and the same is still true for
For what it’s worth, what I decided to do was to replace as much as possible with just
busybox, including the troublesome
psmisc, so that I could drop
ncurses from our firmware altogether — interestingly enough, OpenRC depends explicitly on
psmisc even though it is not bringing in most of the rest of its dependencies.
Public Service Announcement: if you’re writing an init script and you’re tempted to use
replace it with use
command -v instead … depending on an extra program when
sh already has its built-in is bad, ‘mkay?
Edit: people made me notice that
type -p is not in POSIX so it does not work in Dash. I’m afraid that my only trials to run OpenRC without bash before have used BusyBox, which supports it quite fine; the option to use
command -v is valid though, thanks Tim.
Oh right, of course to replace
coreutils usage with BusyBox you have to be able to drop it out of the dependency tree. Sounds easy, doesn’t it? Well, the problem is that even if you’re not deal with PulseAudio (which we are), which brings in
eselect-esd, as of yesterday at least every package that could use Python would bring
eselect-python in! Even when you were setting
Fortunately, after I bitched a bit about it to Luca, he made a change which at least solves the issue at hand until the stupid eclass is gone out of the tree. And yes I’m no longer even trying to consider it sane, the code is just so hairy and so encrypted that you can’t make heads or tails of it.
There are more issues with a project like this that I can discuss, outside of those part that are “trade secret” (or rather business logic), so expect to hear a bit more about it before it’s announced full out. And many of these have to do with how easy (or not) is to use Gentoo as a basis for devices’ firmwares.