[oe] bitbaking aufs

[Vitus Jensen]

On Wed, 24 Aug 2011 11:02:05 +0200 Thomas Zimmermann wrote:
> 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,
...

> 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.

In this case (and in the meantime I came to the same conclusion) it is easiest to use the already patched kernel tree from aufs.sourceforge, create a linux-aufs_2.6.36.bb and use that for my device.  Or have a second look to union-mount (http://valerieaurora.org/union/) and build a recipe for that tree.

Thank you for your viewpoints, they helped.
  Vitus

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