User:Erik Garrison: Difference between revisions

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= XO partitioning.=
Image:Flor_de_ceibo.jpg|A child uses an XO in Uruguay
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== Whoami ==
''Objective'': Implement partitioning to enable the following features:
* Improved OFW-level flash updates. Partitioning can isolate user files from system ones and provide a method to isolate flash updates of the system.
* LZO compression of system and user files. LZO compression can yield large (~500%) disk read/write performance gains over zlib (currently used). The existing single-partition layout would require the introduction of LZO support into OFW. While this might be a useful project, we need not seek to implement every compression format available in the Linux kernel in OFW. Partitioning will allow us to keep the boot partition in a format which OFW can decompress (probably zlib), but move system and user files to LZO to realize performance gains during post-early-boot system operation.
* Boot failure due to NAND fillup. In-field observation suggests that the dangerous situation in which NAND is completely filled arises mostly because users download activities and large media files to their home directories (datastore). Provided system boot can complete without writing to user-controlled partitions (which must be verified), partitioning offers a pattern to protect the system from the effects of such user activity. On its own it won't resolve the less-common problem of system NAND fillup.


Erik Garrison, Davis Square, Somerville resident (I live on the same floor as the [http://www.acetarium.com/ acetarium]). I avidly ride my bike to work. I used to [http://www.hcs.harvard.edu/~harvcrew/Website/# row] but now get my on-water enjoyment from [http://www.community-boating.org/ sailing]. I often [[Muffin man | bring bread]] to the office using money from the [http://spreadsheets.google.com/pub?key=pIt3xaCWJ9eZ9jGaXgTgsag&gid=0| OLPC bread fund], which I manage. I'm easily reachable via IRC; I'm erikg on FreeNode and OFTC's IRC networks. I speak Spanish.
''Major issues'':

* Update of systems from single partition to multiple. The change of partition structure means that system updates will likely have to move user data off the memory device and onto an external storage unit, repartition the NAND, and copy user data back into the new user data partition after the system NAND update is complete. This is a non-trivial support problem. If possible it is strongly desirable to provide a method to update a running system. Doing so will likely require sufficient space to shuffle user data around during update, and it may be that there is no specific solution.
== Projects ==
* Assembly of partitioned images. See: [http://www.nslu2-linux.org/wiki/HowTo/AddJFFS2SupportUsingATrailerPartitionTable]. There is an existing tool (slugimage) which can be used to produce partitions readable by the code in the Linux source tree (drivers/mtd/redboot.c). Assembly should ideally be introduced into the build process.

* [[/rpmxo]] A minimal fedora system bootable from the XO's internal NAND
* [[/Partitioning]]
* [[/Image Digestor]] A script to produce the digests used by OFW during secure reflash
* [[/X Composite tests]]
* [[/Grab key]]
* [[/Mesh routing]] using 80211mac and libertas thin firmware
* [[/Datastore]] and Journal rebase

Latest revision as of 21:49, 16 December 2008

  • A child uses an XO in Uruguay

    A child uses an XO in Uruguay

Whoami

Erik Garrison, Davis Square, Somerville resident (I live on the same floor as the acetarium). I avidly ride my bike to work. I used to row but now get my on-water enjoyment from sailing. I often bring bread to the office using money from the OLPC bread fund, which I manage. I'm easily reachable via IRC; I'm erikg on FreeNode and OFTC's IRC networks. I speak Spanish.

Projects

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