List Archive: gentoo-embedded
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Ed W <lists@...> wrote on 2012/01/23 19:43:49:
> From: Ed W <lists@...>
> To: firstname.lastname@example.org
> Date: 2012/01/23 19:44
> Subject: Re: [gentoo-embedded] quickpkg and PKG_INSTALL_MASK
> On 26/12/2011 18:03, Joakim Tjernlund wrote:
> > I am contemplating a greater problem too. Our system require we can install
> > multiple versions of our SW and switch between them. This is easy to do when it
> > comes to our own app but not when one want to upgrade core parts of the system, like
> > libc etc.
> > So I am thinking one could use --bind mounts and switch_root to solve that. Basically
> > one has a skeleton root FS with /bin, /lib, /usr /opt etc.
> > Each upgrade goes into dirs like:
> > bin_1.x.y/ usr_1.x.y/ lib_1.x.y/ opt_1.x.y/ sbin_1.x.y/
> > Then, from an initramfs, one selects which of xxx_1.x.y dir one wants to use
> > and --bind mounts them under the corresponding skeleton dir.
> I'm doing something like this using aufs. The performance seems "not
> bad", but you get a couple MB or so memory hit. (I'm using squashfs as
> well, so unsure which causes the main memory increase).
hmm, not sure how aufs would work out. One would like to permanently delete the
old sw at some point and I don't see how, perhaps I misunderstand something?
How does aufs do w.r.t power cuts? We need a reliable FS w.r.t power cuts. In the
past we have used JFFS2 on NOR flash and that has worked really well. Now
we need to switch to NAND due to size requirements.
> I think if the device is reasonably beefy then you should have no
> problem with aufs or some similar overlay filesystem (I think some new
> one got added to kernel recently?). Failing that, what about good old
> "cp -a" to merge all the input dirs? Takes some time and disk space,
> but nice and simple?
Not sure I get the "cp -a" idea. You are suggesting to create a new root FS by
copying the non changed dirs from the previous version and combine these with
the new SW?