Gentoo Archives: gentoo-embedded

From: Joakim Tjernlund <joakim.tjernlund@×××××××××.se>
To: gentoo-embedded@l.g.o
Subject: Re: [gentoo-embedded] quickpkg and PKG_INSTALL_MASK
Date: Tue, 24 Jan 2012 08:03:57
Message-Id: OFEBDA1FC0.30EED2E1-ONC125798F.002A27B5-C125798F.002B3E16@transmode.se
In Reply to: Re: [gentoo-embedded] quickpkg and PKG_INSTALL_MASK by Ed W
1 Ed W <lists@××××××××××.com> wrote on 2012/01/23 19:43:49:
2
3 > From: Ed W <lists@××××××××××.com>
4 > To: gentoo-embedded@l.g.o
5 > Date: 2012/01/23 19:44
6 > Subject: Re: [gentoo-embedded] quickpkg and PKG_INSTALL_MASK
7 >
8 > On 26/12/2011 18:03, Joakim Tjernlund wrote:
9 > > I am contemplating a greater problem too. Our system require we can install
10 > > multiple versions of our SW and switch between them. This is easy to do when it
11 > > comes to our own app but not when one want to upgrade core parts of the system, like
12 > > libc etc.
13 > >
14 > > So I am thinking one could use --bind mounts and switch_root to solve that. Basically
15 > > one has a skeleton root FS with /bin, /lib, /usr /opt etc.
16 > > Each upgrade goes into dirs like:
17 > > bin_1.x.y/ usr_1.x.y/ lib_1.x.y/ opt_1.x.y/ sbin_1.x.y/
18 > > Then, from an initramfs, one selects which of xxx_1.x.y dir one wants to use
19 > > and --bind mounts them under the corresponding skeleton dir.
20 > >
21 >
22 > I'm doing something like this using aufs. The performance seems "not
23 > bad", but you get a couple MB or so memory hit. (I'm using squashfs as
24 > well, so unsure which causes the main memory increase).
25
26 hmm, not sure how aufs would work out. One would like to permanently delete the
27 old sw at some point and I don't see how, perhaps I misunderstand something?
28
29 How does aufs do w.r.t power cuts? We need a reliable FS w.r.t power cuts. In the
30 past we have used JFFS2 on NOR flash and that has worked really well. Now
31 we need to switch to NAND due to size requirements.
32
33 >
34 > I think if the device is reasonably beefy then you should have no
35 > problem with aufs or some similar overlay filesystem (I think some new
36 > one got added to kernel recently?). Failing that, what about good old
37 > "cp -a" to merge all the input dirs? Takes some time and disk space,
38 > but nice and simple?
39
40 Not sure I get the "cp -a" idea. You are suggesting to create a new root FS by
41 copying the non changed dirs from the previous version and combine these with
42 the new SW?
43
44 Jocke

Replies

Subject Author
Re: [gentoo-embedded] quickpkg and PKG_INSTALL_MASK Todd Goodman <tsg@×××××××××.net>