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On Fri, May 14, 2021 at 2:36 AM John Covici <covici@××××××××××.com> wrote: |
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> |
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> I would look in the grub.cfg and give us exactly what is in the stanza |
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> you are using, including where it thinks the root file system is, |
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> etc. Also, see if there is any genkernel option to get some debugging |
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> info out of the initrd, I know using dracut you can get breakpoints |
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> during the process and see how its doing. |
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Tried dracut. No change. |
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Added the kernel command line debug options (#3 in “Identifying your |
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problem area” in ‘man dracut’). No change. |
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Feeling peevish, I made a file of random junk using dd if=/dev/random |
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of=initrd.img count=4096. Then supplied that pile of junk as the initrd. |
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Again, no change. |
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Then I supplied a nonexistent file name (xxx.img) as the initrd. This time |
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I got a complaint: |
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error: file ‘/xxx.img’ not found. |
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Press any key to continue... |
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So, it’s getting as far as wanting to read the initrd, and is smart enough |
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to tell whether the specified initrd actually exists on the specified boot |
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partition. But it can’t actually be doing anything with the initrd, or it |
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would have objected to the random junk I fed it. |
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From https://en.m.wikipedia.org/wiki/Initial_ramdisk#Implementation, it |
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appears that grub is in charge of loading both linux and the initrd into |
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memory, then handing execution over to linux along with a pointer to the |
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memory location of the initrd. |
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I’ve observed that that no booting output comes out of linux, nor any |
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complaints from linux about the nonsense contents I fed it from the random |
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initrd I built. That suggests to me that grub has failed to load linux |
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and/or the initrd into memory, or that it's failed to hand execution |
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control to linux. |
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Next step: learned how to run an interactive grub2 command shell. With |
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full debugging turned on, it looks like grub2 can load the kernel image, |
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and it looks like it loads the initrd as well. At least there are no |
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complaints and the reported initrd size looks correct. |
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But when I issue the boot command, grub2 issues a handful of mallocs and |
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does a little token parsing, and then just stops... |
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So it appears that the boot problem arises right around the handoff from |
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grub2 to linux. Don’t know whether grub2 or linux has failed. I don’t |
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know how to get either one to tell me more. |
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John |
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