Hi On Friday 18 March 2011, Daniel Baumann wrote: > On 03/18/2011 01:57 PM, David Kuehling wrote: > > As mentioned before I'm currently trying to make live-boot work for a > > powerpcspe embedded system. Currently I'm testing this with a fat > > partition on a usb hard-disk attached to the system. > > unionfs is going to disappear really soon in 3.x; unionmount support is > not yet in kernel mainline, there's experimental patches against > live-boot available (and it's a quite high priority to get them > merged into live-boot soon). > > or in other words: you will have to patch the kernel, either for using > aufs, or by using unionmount. Fedora uses a devmapper based approach for its live media, which doesn't require any kernel modifications. The basic idea for this is to extend a filesystem loop image on tmpfs backed extents (writable loop image as a sparse file) in RAM. Performance of this devmapper approach appears to be slightly better than aufs, but it also has some drawbacks, namely the filesystem overhead for the required loop image (~about 35-50 MB for an ISO image), having to define a fixed maximum size for the sparse file at boot time and larger RAM requirements, but it does work with pretty much any unpatched mainline kernel with devmapper support enabled. We added this functionality to aptosid some time ago, when aufs' future appeared to be quite uncertain, but never actually used it in a release because of the afforementioned disadvantages; it should be relatively easy to port similar functionality to live-boot though. Of course, VFS based union mounts are the way to go and the ideal/ final solution to this problem, unfortunately it appears that its development has seriously lost momentum recently and it becomes questionable when or /if/ this functionality will be merged mainline. Another potential alternative would be OpenSuSE's (kiwi) fuse based approach, however we didn't actually test that (as we'd like to avoid 'large' userland/ fuse dependencies in the initramfs). Regards Stefan Lippers-Hollmann, aptosid developer  http://svn.berlios.de/wsvn/fullstory?op=comp&compare%5B%5D=%2Ffll-live-initramfs%2Ftrunk%2Fscripts%2Ffll%4028103&compare%5B%5D=%2Ffll-live-initramfs%2Ftrunk%2Fscripts%2Ffll%4027340 (plus a small bugfix in r28658) Vcs-Svn: svn://svn.berlios.de/fullstory/fll-live-initramfs/trunk Vcs-Browser: http://svn.berlios.de/wsvn/fullstory/fll-live-initramfs/trunk/
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