[Nix-dev] Grub problem: external pointer tables not supported

[Roger Qiu]

Hey glad you solvee it.

So the problem was that you were using Grub to directly access ZFS root
drive to get the kernel, but Nixos uses lots of hardlinks and Grub has a
problem reading that. So the kernel is now copied to /boot. That's actually
how it's done in gummiboot and probably other bootloaders.

Thanks,
Roger
On 24/01/2017 12:52 PM, "Tomasz Czyż" <tomasz.czyz at gmail.com> wrote:

> It looks like I hit some ZFS feature that it's not supported by grub
> module.
>
> How I found that?
> In grub, you can list files in zfs volumes by doing ``ls $drive/@/home``
> etc.
> I could list ``ls $drive/@/nix`` or ``ls $drive/@/nix/var`` but not ``ls
> $drive/@/nix/store`` where I kept the kernels.
>
> I found some explanations about lot's of files and lot's of hardlinks (nix
> store had at that time more than 130G and probably triggered the feature).
>
> nix-collect-garbage -d didn't help.
>
> I solved the problem by using boot.loader.grub.copyKernels = true;
>
> Kernels were copied to the same volume but to /boot where there is smaller
> number of files and worked perfectly.
>
>
> 2017-01-23 16:44 GMT+00:00 Tomasz Czyż <tomasz.czyz at gmail.com>:
>
>>
>>
>> 2017-01-23 16:15 GMT+00:00 Roger Qiu <roger.qiu at matrix.ai>:
>>
>>> Hey,
>>>
>>> Changing nixos generations won't affect the grub boot partition, that
>>> only changes which nixos kernel and initramfs image gets booted.
>>>
>> Because all boot options are not working one of my guesses is that in new
>> nix version, wrong config was generated when I did system update which
>> broke all options.
>>
>>> This looks like an error in the Grub partition. Maybe you recently
>>> updated it or changed it, or the partition got corrupted.
>>>
>> It's possible, I tried to boot from USB, do ``nixos-install
>> --no-root-passwd`` to reinstall the system, but I'm not sure how to force
>> grub/uefi partition recreation/reinstalling, any idea? Should I just format
>> it and will be recreated?
>>
>>> This is why other operating systems tend to make their /boot read-only...
>>>
>>> If you can't get into the OS, then you can try booting off a USB, and
>>> then edit the boot partition. Or run the uefi terminal app (but this one
>>> never worked for me). If you had cloned/raided boot partitions you can try
>>> changing the uefi image to boot from in your uefi settings (access it like
>>> BIOS).
>>>
>> I tried that, but I'm not sure what to change. I tried to reinstall grub
>> on EFI partition but I'm not sure how to do that, is regular grub-install
>> stuff way to go (I thought I had some issues with that and I tried
>> nixos-install after that).
>>
>>> Currently I have 2 uefi boot partitions cloned, but one failed so I've
>>> been booting off the other one.
>>>
>> Nice one, I think I'll try to do something like that.
>>
>> Thanks Roger.
>>
>>> Thanks,
>>> Roger
>>> On 23/01/2017 10:48 PM, "Tomasz Czyż" <to <tomasz.czyz at gmail.com>
>>>
>>
>>
>>> masz.czyz at gmail.com <tomasz.czyz at gmail.com>> wrote:
>>>
>>>> Hello,
>>>>
>>>> recently my grub said this to me after I restarted computer:
>>>>
>>>> Error: external pointer tables not supported
>>>> Error: you need to load the kernel first.
>>>>
>>>> Every option I select with nix (also past generations) shows me this
>>>> message.
>>>>
>>>> I updated the system to 17.03pre99792.c311871 on 2016-12-23 and
>>>> restarted it before multiple times (and worked). I don't remember if I did
>>>> other updates, but this is what's grub menu shows me.
>>>>
>>>> My disk layout is: EFI boot partition for grub, next partition is
>>>> encrypted luks volume and ZFS on top of it.
>>>>
>>>> This setup worked for me for 1.5 year now without any issue.
>>>>
>>>> Anybody is aware of any changes to grub/zfs recently or had same issue?
>>>> Any suggestions how I can recover from it or what can be wrong?
>>>>
>>>> Tom
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> nix-dev mailing list
>>>> nix-dev at lists.science.uu.nl
>>>> http://lists.science.uu.nl/mailman/listinfo/nix-dev
>>>>
>>>>
>>
>>
>> --
>> Tomasz Czyż
>>
>
>
>
> --
> Tomasz Czyż
>
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