Error screen at system startup after kernel update 4.4.0.108.

I strongly recommend NOT INSTALLING the kernel update 4.4.0-108 for linux systems. It has gone out to solve the vulnerabilities in the processors with speculative execution Meltdown and Specter.

Reasons for the update.

This year has started with notifications of vulnerabilities in the processors of the most important brands. It affects both Intel and AMD, but also to the ARM processors, this means that android devices are also exposed.

The problem was notified to the manufacturers in June 2017 from Google’s Project Zero. Since then it has managed to exploit the vulnerability by showing passwords, images, etc. In general, parts of memory that are in the area of other users or even in the area of system. Moreover, in systems running virtually, you can access memory from other systems or the host.

It is a design problem in processors that perform speculative (or predictive) execution to accelerate processing. When it get to a fork in the code, the processor choose a path and move forward hoping that they have succeeded for save time, if not, the incorrect part is discarted and continue execution on the correct path.

The error is that some data remains in the processor’s cache for a while and, as this memory is very fast, it’s possible to read a lot of information that the user have not access normaly.

As this is very serious there is already an update for the different operating systems and programs. When speculative execution is removed some processing speed is lost, but how much it is not so clear, some people say that up to 30%, others that is insignificant, I suppose it will depend on what is being executing.

If you have already done so, you can choose another version of kernel in the grub start menu in “advanced options for ubuntu”

Greetings and happy year 2018