How do I remove a tunable that I added that stopped my system from booting properly?

biltong

Dabbler
Joined
Apr 21, 2015
Messages
13
I just saw some posts on getting Plex hardware quicksync acceleration wroking in jails and thought I would give it a shot. I did a
Code:
kldload /boot/modules/i915kms.ko
on my running system and that worked fine, I was able to see the necessary devices in /dev/ and my display was now running at native resolution. So I thought I would be fine to add the module to load at boot time.

I added "i915kms_load" as a loader tunable with the value set to "YES" and rebooted. The system definitely does load the module, I can see it in the early output of the boot process. Shortly later after initializing my USB devices, the screen goes black and the system appears unresponsive. Doesn't look like my system is active on the network as I can't SSH in nor can I get to the UI, both just time out.

So clearly something isn't quite right. Now, is there any way for me to remove that tunable? I can boot to another environment from an earlier update sure, but is it possible to "edit" my current live one (11.2-U4) and get it back?

EDIT I just tried this method here: https://www.ixsystems.com/community/threads/setting-tunables-at-time-of-install.71985/#post-504420

At the loader prompt I entered
Code:
set i915kms_load=NO
and booted, same behaviour continued. I tried the same thing with quotes around the NO and didn't get anywhere with that either. :(

I am successfully able to boot to an earlier boot environment, and given that 11.2-U4.1 is out I could just update to that as I don't think I made any config changes between 11.2-U1 which is the last stable environment I had, and 11.2-U4 which was working fine till I started dicking around with it.

It looks like the i915kms module either isn't actually being loaded properly, or isn't being respected because right after kernel modules are loaded I see some output from the vga driver and my console resolution is stuck at 640x480. It also looks like the system borks right around the time it tries to mount root, judging by the timing from the working environment and when my broken one tries to boot.

EDIT 2 looks like the module being loaded that early is the wrong version according to this reddit comment https://www.reddit.com/r/freenas/co..._on/egifciv?utm_source=share&utm_medium=web2x

I am running on an i3 4160 which appears to only be supported by the module available from ports, which means I need to wait for root to be loaded to load the correct version of the module.
 
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