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On Sat, 27 Mar 2021 18:40:52 -0400 |
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Joshua Kinard <kumba@g.o> wrote: |
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|
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> On 3/27/2021 18:16, James Le Cuirot wrote: |
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> > On Sat, 27 Mar 2021 17:43:34 -0400 |
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> > Joshua Kinard <kumba@g.o> wrote: |
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> > |
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> >> I kinda wish the Linux kernel had an ability to partially boot, init the |
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> >> networking subsystem, then fetch an initramfs image over TFTP like it can do |
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> >> with NFS Root. That would solve the problem on my MIPS system(s) (and make |
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> >> install netboots better). I've dug around, but this does not seem to be a |
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> >> capability currently in the kernel, unless I have over looked something. |
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> >> |
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> >> Otherwise in the future, I may just have to setup an initramfs into an NFS |
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> >> Root and teach the SGI's to somehow deal with it. Which all still seems |
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> >> unnecessarily complicated because some other distro thinks it knows what's |
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> >> best for everyone else (but I digress...). |
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> > |
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> > NBD may be a slightly simpler alternative and a bit more like an |
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> > initramfs. nbdkit can do all sorts of weird things. I thought it might |
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> > have a plugin for cpio archives, allowing you to use a regular |
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> > initramfs generated by Dracut or similar directly. It doesn't appear to |
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> > but plugins are quite easy to write. Alternatively you could just |
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> > extract the initramfs and use nbdkit-linuxdisk-plugin. |
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> |
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> Can NBD be used like I described? Never played with it before. The MIPS |
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> machine has functioning local disk drives, and currently, it boots fine by |
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> just pulling a kernel off my TFTP server and booting from the local drive, |
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> no initramfs needed because I compiled everything into it. If we ever force |
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> sep-usr to end, then I'll need a way to teach it to mount /usr before |
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> dropping into /bin/init (and nothing else). |
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Apologies, I went to experiment with this idea but I'd forgotten that |
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booting over NBD is not a built-in kernel feature and requires... an |
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initramfs. NFS looks like the only option with this general approach. |
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Rich is right though, the initramfs can be tiny. Dracut images are |
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heavy because they are very flexible and pack a lot of features but |
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none of that is required. |
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The kexec idea would be a nice bonus for you, if it works. Limiting |
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what kernel features you can enable must be frustrating. |
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It's also worth bearing in mind that you could just generate an image |
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with Dracut and extract it to a disk partition. That may seem a little |
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pointless if you're not using something like LVM or encryption but I |
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don't see the point in separate /usr either. ;) I'm guessing you don't |
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want to change your partition layout at this point though. |
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|
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-- |
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James Le Cuirot (chewi) |
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Gentoo Linux Developer |