Re: bitbaking aufs

[Thomas Zimmermann <ml@vdm-design.de>]

On Wednesday, August 24, 2011 00:11:39 Vitus Jensen wrote:
> Hej!
> 
> I would like to use a layered filesystem in our ppc603e-based machine: the
> rootfs built from openembedded would be read-only, any customizations go
> to a writable filesystem and should the need occur to start fresh all I
> need is a mechanism to remove the contents of the writable filesystem.
> 
> In openembedded (2011.03) there is unionfs and aufs
> (http://aufs.sourceforge.net/), aufs is more actively developed so I would
> like to use that.  Unfortunately the recipe in oe uses aufs1 which does
> not support current kernels.  Could change that to aufs2.2 but
> aufs2 now has two seperated repos (patched kernel or source plus patches =
> "standalone") and I'm in doubt how to proceed.  Especially as aufs_cvs.bb
> contains some CONFIG_xxx voodo.
> 
> My intention is to use the "standalone" repo and "inherit module" from oe
> but how do I apply kernel patches in this case?  The kernel resides in
> ${TMPDIR}/sysroots, do I patch that???  Or do I have to apply those
> patches during kernel build?  I could extract them from git and add them
> to the kernel recipe for my machine but this doesn't feel right,
> 
> I think, I need some advice how to best get aufs2.2 building.  And a good
> example for a "inherit module" recipe using sysroot kernel source might
> help.  Which should I use as example for aufs?
> 
> Best regards,
>     Vitus

You have to patch the kernel to export a lot of symbols for aufs2. So you have 
to rebuild the kernel anyway. And then i think it would be the easiest way if 
you integrate it into your kernel directly. Like described in the README 
section 3.1.

In my opinion a standalone aufs recipe is not possible, because the kernel 
needs to be patched and you have to use the specific branch for your kernel 
version.

Regards
Thomas