Re: newer releases of various kernels cause boot to hang with ZFS

[voidlinux-github@inbox.vuxu.org]

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New comment by emacsomancer on void-packages repository

https://github.com/void-linux/void-packages/issues/12519#issuecomment-503410468
Comment:
Ok, so debugging this was a bit tricky. The gist is this: the recentness of the kernels was a red herring, the crucial factor was whether the kernel was installed before or after the zvol swap file was created. All kernels created after swap was created end up with a dracut configuration which (apparently by default) assumes that swap will be used for resume, and when booting any of these kernel results in dracut waiting about 2 minutes trying to finding the swap partition (so these kernels do *eventually* boot). 

So I'll close this issue (which wasn't what it appeared) but document a possible resolution:

One Potential Fix
==========
I don't really use resume, so at least one easy fix for this issue is to create a dracut conf file, e.g.:

/etc/dracut.conf.d/omit-resume-for-zvol-swap.conf containing:

`omit_dracutmodules+=" resume "`

and call `xbps-reconfigure -f` on the relevant kernels.

I'm not sure if a zvol swap can be used for resume/seen at the appropriate time by dracut or not.

Using Swap on ZFS root?
==============
It's possible that the location of the swap partition could be specified in a way that dracut could locate it (though, again, not using resume, I'm not sure about swap size requirements for using resume). zvol-type swap ends up being mounted on `/dev/zvol/<POOL-NAME>/swap`. I think dracut looks for the resume/swap to be located at `/dev/zd0`.

 I'll investigate further. But for now there's at least a clear fix for this issue, which turns out not to be at all what it first appeared.