On 01/29/2012 12:00 PM, Robert A. Lerche wrote:
Hi. I have previously built LFS and used the LFS Live CD project to
create a custom system (back in the 6.3 / 6.4 days).
I am now engaged in a project for a client using Android on a custom
embedded system. As you may know, Android uses the Linux kernel as a
base.
Has anyone out there built Android completely from sources?
Yes, even been through the joy of adding a new device at one point,
though people much smarter than I have superseded anything I might have
accomplished in my own impatience. Took me several hours to figure out
how to get the sucker to boot the first time.
I'd
appreciate a chance to chat with someone familiar with setting up a
complete source build environment.
See the IRC link below if you'd prefer direct chat to others methods of
information gathering...
Thanks in advance.
While the final product is not even remotely similar to LFS, you will
still find quite a bit in common with LFS in that massive 6GB source
tree, but still way more differences. You will need a proper mult-lib
setup on your build host, however, which renders LFS proper useless for
Android development. See CLFS if you really want to use *LFS as a build
host. I use Ubuntu in a VM myself. It's not terribly difficult to build
a cross toolchain from scratch either should you need it for projects
outside the tree, see codesorcery's open source changes.
IMO, the biggest pain of building android is learning to use the repo
script instead of git by itself. You are actually pulling code from from
around 200 (or potentially more) git repositories for the Android source
tree. The repo tool attempts to simplify that a bit, keeping a manifest
file which describes all of the various git repos and local paths, but
it, like any other tool, has a couple of gotchas. Do not try and change
the path after you have done an init, remove the entire tree and start
from scratch. Also, make sure it is more than one path element deep
below your home directory...use something like ~/Android/AOSP and
~/Android/Evervolv, not ~/AOSP and ~/Evervolv. If you ignore this last
bit, you won't like the result when you elect to remove one of the trees
by choice, followed by the other as necessity (note that git itself will
still work correctly so that you can push your changes back to github,
or wherever). I never did dig in and figure out the cause, but it does
not make a happy developer when it fails (and gives weird errors as
well, usually revolving around the .repo directory).
As mentioned by another poster, CyanogenMod has a great wiki and could
be used as a good starting point I suppose, but they are maintaining
something like 70+ devices now and have many many differences to AOSP.
If you are looking for examples, I think I'd look at a project that
manages less devices (Evervolv is one I follow and much much closer to
AOSP proper) for figuring out custom device profiles (and mealtime
functions (lunch/brunch) which are heavily modified in CM's repos).
Probably look for something with similar hardware to your new target and
go from there. Just about everyone uses github, so remember to include
it in your search terms if looking for direction.
Links:
I'm sure you've found this one already, at least I hope you have:
http://source.android.com/source/downloading.html
CodeSorcery (custom cross toolchain, not actually needed unless you
intend to develop in C outside of the Android source tree, probably just
use the one in git):
http://www.mentor.com/embedded-software/android/
CyanogenMod (great documentation, but probably overkill as a source for
creating a new device tree):
https://github.com/cyanogenmod
http://wiki.cyanogenmod.com/index.php?title=Main_Page
They also have a freenode IRC channel for developers, but I don't know
it off the top of my head. Some really smart people in there too.
Evervolv (one suggestion for example code for a new device tree (in
addition to the ones already in AOSP, there are many others out there as
well, but these guys tend to keep it simple enough, and the devs on IRC
will likely bend over backwards to help):
https://github.com/Evervolv
http://wiki.evervolv.com/index.php/Main_Page
irc://irc.freenode.net/#evervolv
Hope that gets you going in the right direction.
-- DJ Lucas
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