On Sun, 2007-06-24 at 12:46 -0400, C. Scott Ananian wrote: > Sorry, wrong email... > --scott > ---------- Forwarded message ---------- > From: C. Scott Ananian <[EMAIL PROTECTED]> > Date: Jun 24, 2007 12:44 PM > Subject: XO in-field upgrades > To: [EMAIL PROTECTED] > Cc: Christopher Blizzard <[EMAIL PROTECTED]>, Michail Bletsas > <[EMAIL PROTECTED]>, John Watlington <[EMAIL PROTECTED]>, > [email protected] > > > In the weekend I just read about Alex' plan for XO in-field upgrades. > The mailing list message is here: > http://lists.laptop.org/pipermail/devel/2007-June/005381.html > I think the proposal deserves more discussion; in particular there are > some interactions with vserver and copy-on-write, as well as > networking (I really don't want the laptops broadcasting information > about what upgrade blobs they have on mDNS! We should use a multicast > address at least...) Also, I think we've discussed shipping binary > diffs rather than git's integral blobs, which may (or may not) be > incompatible with the proposal so far. Fundamentally, I don't think > that re-using git's design philosophy wholesale is actually the Right > Thing for this application.
For the stuff in that mail I don't see how vserver and copy-on-write has any bearing. That mail is strictly about how to get the bits of a specific update to the laptop. How we then later apply the bits to the machine is a different thing. mDNS *is* multicast. But the blobs won't be exposed over mDNS, that is far to much data for a protocol like that. mDNS is just used to announce "here is a laptop that has this version of the image installed", and if the version is later we can upgrade another laptop from that one. Binary diffs seem much less useful. They enforce a specific base version that you have to have around, and they enforce the direction of upgrade. If you can cheaply generate at runtime (on the client) a minimal diff between any two versions you can avoid storing unnecessary information, and you can upgrade between any two versions (including going backwards). I find that quite superiour to having to e.g. upgrade multiple steps by using multiple diffs. _______________________________________________ Devel mailing list [email protected] http://lists.laptop.org/listinfo/devel
