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On Fri, Aug 2, 2013 at 8:06 AM, Duncan <1i5t5.duncan@×××.net> wrote: |
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> Steven J. Long posted on Fri, 02 Aug 2013 12:31:08 +0100 as excerpted: |
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> |
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>> As Rich said, lvm doesn't link outside rootfs so it's not an issue: you |
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>> only really need an initramfs if rootfs is on lvm/encrypted/raid, or you |
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>> need udev to get through localmount. |
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> |
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> Or, unfortunately, for root on mult-device btrfs[1], since the usual |
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> kernel commandline rootflags=device=/dev/whatever doesn't seem to work |
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> for some reason.[2] |
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> |
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> Tho hopefully that bug will be fixed before the "experimental" label is |
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> stripped from btrfs... |
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> |
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Passing rootflags=device= is a little fragile anyway, since it depends |
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on the kernel detecting your devices in a certain order. Having a |
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multi-device btrfs root without an initramfs is asking for trouble. |
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> --- |
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> [1] Yes, as appropriate for running on an experimental fs, I have |
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> backups, tho the dual-device raid1 mode I'm using is /reasonably/ stable, |
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> now. I switched to btrfs when I upgraded to ssd, both for the ssd |
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> support and for checksummed data/metadata with a second copy to retrieve |
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> from if the first fails the checksum. |
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> |
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> [2] I tried with a btrfs raid1 and could mount either device with root= |
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> and rootflags=degraded, so it was definitely parsing rootflags, but no |
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> way was it taking rootflags=device= to mount them undegraded without a |
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> userspace btrfs device scan first, and that requires an initr*. Maybe it |
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> was a problem with the kernel splitting at the second = instead of the |
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> first, I don't know, but it definitely wasn't working. So now I'm |
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> running dracut with several of its default modules stripped via |
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> INSTALL_MASK including the one pulling in kmod since I'm running |
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> monolithic kernel and have kmod package.provided, and USE=btrfs plus |
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> adding it to the module config. |
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> |
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If you just want a minimal initramfs that calls btrfs scan on boot |
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without hacking the crap out of dracut, feel free to use my little |
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homegrown project. Just adjust the paths, make sure your busybox is |
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static, and you should be good to go. |
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|
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https://bitbucket.org/floppym/initramfs/src |
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