Comment 25 for bug 1742675

Since it is probably due to Meltdown+Spectre patches we've probably missed additional parameter - intel microcode used to build initramfs. It has changed 2018-01-08 to new one but was changed back to old one yesterday because many users reported boot and stability problems. It for sure affects boot and generally "behavior". So to be sure that i use correct microcode i've updated to lates on as of today and regenerated all initramfs files fo all installed kernels doing:

sudo update-initramfs -u -k 4.4.0-112-generic

and so on for all kernels.

Now linux-image-4.4.0-112-generic works for me most of the time. Sometimes it hangs during boot (about 1 in 3 boots) but once it boots everything is ok and additionally Meltdown+Spectre is fully fixed (according to checker script).

But still there are problems with latest versions of 4.10 and 4.13 kernels.
Mainline kernels work for me since they don't have all patches for Meltdown+Spectre (or even if they have them as a code, they need updated toolchain to be used to compile them to activate these patches but automated build system for mainline PPA doesn't support it for now).

It look in general like in my case (Asus Zenbook UX305FA with Intel Core M-Y510) Meltdown+Spectre patches are OK when they are applied to 4.4 kernel but they break my laptop when applied to more recent kernels.

On the other hand every kernel works on my "big" PC with AMD Athlon.