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On Thu, May 28, 2015 at 12:46 PM, Rich Freeman <rich0@g.o> wrote: |
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> |
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> On Thu, May 28, 2015 at 11:57 AM, Canek Peláez Valdés <caneko@×××××.com> |
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wrote: |
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> > Others have already answered, but I will add that if you put "emergency" |
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> > anywhere in the kernel command line, then systemd will boot to the |
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rescue |
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> > target; that's why I suggested to do it in my first answer. |
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> |
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> I'm pretty sure that won't work for an initramfs - they're almost |
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> certainly designed to ignore that instruction. |
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Actually, it does work (see attached screenshot). I set my root= kernel |
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command line parameter wrong on purpose, and systemd (inside dracut) |
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dropped me inside a rescue shell. |
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That's a full systemd instance, I could journalctl'd things and start and |
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stop services... only those inside the initramfs, of course. |
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> Usually when somebody |
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> wants a rescue shell, they want it in their root filesystem, and not |
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> in their initramfs before it has pivoted. That is why dracut has |
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> options like rd.break. |
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But that doesn't help you at all when the problem is exactly that you |
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cannot mount your root filesystem. With the rescue shell of systemd (inside |
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dracut), you can analyze the problem, or perhaps even mount your root |
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filesystem and continue the boot process; the initramfs should have all the |
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necessary tools to do that. |
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> If the problem were with systemd/services/etc in the actual root |
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> filesystem (once the actual distro has started booting), then putting |
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> emergency on the command line should get you a rescue shell. |
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Again, what if the problem is before *that*? |
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> The same generally applies to openrc - if the initramfs isn't mounting |
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> your root filesystem, then passing instructions to openrc won't do |
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> anything since in that case openrc isn't even running. |
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But in this case, systemd *is* inside the initramfs: |
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# ls usr/lib/systemd/ |
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network systemd-cgroups-agent systemd-journald systemd-shutdown |
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systemd-vconsole-setup |
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system systemd-fsck systemd-modules-load systemd-sysctl |
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system-generators |
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systemd systemd-hibernate-resume systemd-reply-password systemd-udevd |
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That's my initramfs. With dracut, systemd *is* the initramfs init system. |
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Regards. |
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-- |
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Canek Peláez Valdés |
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Profesor de asignatura, Facultad de Ciencias |
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Universidad Nacional Autónoma de México |
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