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On 20/08/2013 16:08, Tanstaafl wrote: |
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> On 2013-08-20 8:22 AM, Neil Bothwick <neil@××××××××××.uk> wrote: |
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>> On Tue, 20 Aug 2013 14:10:21 +0200, J. Roeleveld wrote: |
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>> |
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>>>> Not really, because make is intelligent enough to no bother |
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>>>> recompiling anything for which the source has not changed. |
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>>> |
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>>> True, but why recompile the kernel just to redo the initramfs? |
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>>> As mentioned, I don't update/recompile the kernel as often. |
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>>> "genkernel" puts the initramfs where it needs to be, kernel-make |
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>>> doesn't. |
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>> |
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>> That depends on your needs. The reason I do it this way is so that the |
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>> initramfs is locked to the kernel. Once that kernel boots, it will always |
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>> boot because the initramfs cannot be changed. If I make a change to the |
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>> initramfs, that's a new kernel and however broken it may be, the old one |
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>> will still work. |
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> |
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> So, you're saying that whoever it was that said that some userland files |
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> (that the initramfs 'refers to') could get updated, causing it to get |
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> out of sync - and presumably causing it to fail to boot if/when you |
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> rebooted - was wrong? |
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> |
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> The main thing about this whole initramfs thing is, like Dale, I just |
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> don't understand it. I understand grub and grub.conf. I understand |
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> enough about compiling a kernel to be able to get it done and be |
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> reasonably sure it is done right. |
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What part don't you understand? How to use it, how it works, how to |
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build it? |
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The full correct way to test such a thing is to configure and build the |
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new kernel, build the initramfs, install the whole lot, add new stanza |
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to grub.conf and reboot. If it fails, reboot with the old kernel, then |
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investigate. |
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You have servers and the only time you would really be building a new |
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kernel is to do an update you plan to use, correct? Presumably you have |
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a defined maintenance window for that, so make full use of the time. You |
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can copy debian's scheme in grub.conf to configure a known good fallback |
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that will be used if the boot fails. |
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> |
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> But if my system ever failed to boot because of a problem with the |
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> initramfs, I basically would be hosed. |
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You can't fix them (well, not easily), you just rebuild them. |
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If it helps, think of an initramfs as a minimal system image that is |
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compressed and stored in a file. The kernels mounts it at /, uses it |
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briefly to looad some drivers and do kernel-space setups then invokes |
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some internal magic to toss it and mount the real (and now accessible) / |
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correctly. It's magic because you cannot do this anymore once init has |
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started |
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> |
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>> The kernel and initramfs are so closely coupled, it just seems sensible |
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>> to keep them in the same file, since neitherof them is any use without |
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>> the other. |
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> |
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> See above... |
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> |
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-- |
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Alan McKinnon |
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alan.mckinnon@×××××.com |
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