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On 29/09/2013 19:43, Tanstaafl wrote: |
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> On 2013-09-28 6:46 PM, Neil Bothwick <neil@××××××××××.uk> wrote: |
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>> Except you can never break Gentoo with a kernel update because, unlike |
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>> some other distros, installing a new kernel does not uninstall the |
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>> previous one. No matter how badly wrng a kernel update goes, you can |
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>> always hit reset then select the old one from the GRUB menu - |
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>> reinstallation doesn't come into it. |
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> |
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> My understanding is that this is not true, and that a USERLAND update |
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> (LVM2, which I use, among them) can cause breakage that will cause the |
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> CURRENT kernel+initramfs to no longer boot. |
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> |
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> Is my understanding flawed? |
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No, this can happen in theory. It's quite simple to describe in somewhat |
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abstract terms: |
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Imagine for example that LVM makes a backwards-incompatible change to |
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it's metadata. You are warned about this and take care to update your |
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kernel so that it can deal with the new metadata by including support |
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for both formats. |
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And you forget to update the initramfs. Reboot. Oops. |
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This is merely highly inconvenient, not the end of the world. Download a |
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very recent rescue disk on another computer and boot with that to effect |
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the repair. Then leave work and make your local publican's day whilst |
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you vent your fury yet again |
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Point is, this is not a situation unique to kernels, userlands and |
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initramfs. That kind of error can occur in so many different ways (eg |
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deploy a seriously broken linker and loader, or simply uninstall bash on |
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a RHEL4 host), it's just that when it happens in the circumstances you |
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ask about, it's one of the most inconvenient errors in a huge list. |
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This is why we sysadmins have jobs - we are supposed to have subtantial |
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clue and be able to predict and avoid such goofs. |
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> Totally side question: Anyone ever hear Linus' opinion of an initramfs |
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> being required to boot a system? |
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Never read it myself, but I'll hazard a guess: |
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He detests it with a passion calling it a grotesque hack, but tolerates |
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it because binary distros need it and no-one has come up with something |
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better (i.e. it sucks less)? |
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-- |
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Alan McKinnon |
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alan.mckinnon@×××××.com |
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