[MULTI BOOT] ERROR while booting 'failed to set xfermode '

[blackjack]

6.966283] ata1.00: failed to set xfermode (err_mask=0x40)

Hello
I'm getting this message and a slow boot on ubuntu 18.04 with kernel 4.20. however this does not occur when i use kernel 4.15. any kernel after that gives me this message during bootup. Any advice on how to fix please?

Kde neon 18.04 , dell latitude e6430

[oshunluvr]

Go back to 4.15. 4.20 hasn't been released for 18.04 yet.

ata errors are drive interface errors. Your drive controller isn't working as it's currently configured. If you knew enough about kernel compiling, you'd probably can fix it yourself. Otherwise, I wouldn't expect that to be your only issue.

From: http://ubuntuhandbook.org/index.php/...tu-linux-mint/

The mainline kernels do not include any Ubuntu-provided drivers or patches. They are not supported and are not appropriate for production use

[v7peer]

If it works on kernel 4.15 then I would suggest that you use this kernel and lock it so it cannot update anymore.
In Synaptic you can lock the kernel easily and of course you can lock it in the terminal (I do not now the command)

[jglen490]

There's really no need to lock the kernel, just be very careful about deliberately going out of bounds on the supported kernels for 18.04. If you absolutely feel the need for a more recent kernel, then investigate newer versions of the distro.

[oshunluvr]

Just so everyone is clear about this topic; This 4.20 kernel did not come from Ubuntu in the form of an update or installed from a supported channel.

The OP deliberately went "off campus" and installed an unsupported, untested, and/or un-configured kernel. I have no problem with someone doing that, but you must be totally clear that you will have to recompile the kernel to get it to work and you must expect and be prepared for failures. It is possible to do all this, but it requires knowledge of how to do so, what to configure and add-in, and the time to do it right In my early days with Linux and PCs back then of much less RAM, power, drive space, etc., "rolling-your-own" kernel wasn't uncommon. However, it often took weeks to get it right and anything you decided you didn't need in there wouldn't magically work later on. This is not a small task. I encourage everyone to learn and dig in and try it, but not on a computer you plan to use for daily activities. The kernel contains, among other things, the settings and drivers that we rely on to make our systems work. In this day and age of computing, the need to shave a few bytes off your memory profile or pull out a bunch of drivers you know you won't use to save a couple hundred bytes of drive space just simply isn't worth the effort. Do it to learn, as a hobby, or because it's there, but don't expect it to "just work." The Ubuntu and KDE developers spend a lot of time and energy getting things to "just work" for us and I don't take that for granted.

Going outside the gates and doing your own thing is fine, but in most cases you're on your own.

[blackjack]

The mainline kernels do not include any Ubuntu-provided drivers or patches. They are not supported and are not appropriate for production use

AHHHH thanks ! I did not know this. Im trying out btrfs on my laptop and I have read on many places to keep the kernel up to date.That is why I updated via ukuu.
I seem to get poorer battery life on btrfs on my laptop compared to ext4. I was wondering whether this was due to the inbuilt compression in btrfs. (does anyone know if it is on by default at OS installation ?) I hoped a newer kernel would improve things.