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