joerg.faschingbauer at aon
Aug 9, 2009, 11:02 AM
Post #4 of 6
>>>>> "Ed" == Ed W <lists [at] wildgooses> writes:
>> When all packages have been stacked, hook scripts that come with the
>> packages are run in a chroot. For example, packages can add their own
>> init scripts by calling rc-update, or add users, or whatnot.
Ed> I assume you run these hook scripts each time you boot then? This
Ed> seems like a good idea, I had been thinking about putting that on the
Ed> writable partition and dreaming up some way to ensure that the scripts
Ed> were only run once - I think your design is cleaner (although need to
Ed> watch boot speeds)
You definitely have to. Although our platform is "embedded" in a sense
that it has no keyboard and mouse, and that it has to "just work", it
has a dual core 2GHz Intel. This is not to say that boot is slow
(rc-update does not crunch numbers), it's just that it is fast enough
and we didn't invest much to speed it up.
Ed> I would be very interested to pick over your implementation details if
Ed> you were willing to share (offlist if you don't think it's sensible to
Ed> post publically?). I'm quite interested in how you picked the package
Ed> list and ordered them and exactly how you implemented the hook scripts
Ed> and failure conditions?
Unfortunately I did the work for my employer, so I cannot share it
with you, at least not character by character.
One package (one ISO) contains several directories which become aufs
branches during boot, and a dedicated single directory that contains
00base-os -> ../base-os
10core-modules -> ../blah
It's these links that give the order of the stack, and it's actually
the links that are being stacked. You need this order because (at
least) the base OS install has to come first. Other packages may
overlay files from there, for example /etc/X11/xorg.conf or
>> What I am extremely excited about is that everything worked right out
>> of the box. Not even one single problem. I expected aufs to fail with
>> many branches (currently we have some 50 of them), busybox to be not
>> compatible enough with the shell, initramfs to impose too many
>> restrictions ... - nothing.
Ed> That's really good to hear! I am currently only planning about 3-4
Ed> packages, but based on what you say I might look to split my packages
Ed> more granually...
Definitely. What I did was to keep things separate when they are not
related to each other. Some of the directories have a tree structure
that hosts only one single file. I don't have 50 ISO files around
though - I aggregate many directories into one ISO.