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Linux 4.15 Released

Jan 28, 2018, 19:56 (0 Talkback[s])
(Other stories by Linus Torvalds)
After a release cycle that was unusual in so many (bad) ways, this
last week was really pleasant. Quiet and small, and no last-minute
panics, just small fixes for various issues. I never got a feeling
that I'd need to extend things by yet another week, and 4.15 looks
fine to me.

Half the changes in the last week were misc driver stuff (gpu, input,
networking) with the other half being a mix of networking, core kernel
and arch updates (mainly x86). But all of it is tiny.

So at least we had one good week. This obviously was not a pleasant
release cycle, with the whole meltdown/spectre thing coming in in the
middle of the cycle and not really gelling with our normal release
cycle. The extra two weeks were obviously mainly due to that whole
timing issue.

Also, it is worth pointing out that it's not like we're "done" with
spectre/meltdown. There is more work pending (arm, spectre-v1, misc
details), and perhaps equally importantly, to actually get the biggest
fix for the indirect branch mitigations, you need not just the kernel
updates, you need to have a compiler with support for the "retpoline"
indirect branch model.

You can do

cat /sys/devices/system/cpu/vulnerabilities/spectre_v2

and if you don't have a compiler that supports the retpoline
mitigations, you'll get:

Vulnerable: Minimal generic ASM retpoline

because only the assembly code (not the C code) will have the
retpoline mitigation. So keep that in mind.

Anyway, while spectre/meltdown has obviously been the big news this
release cycle, it's worth noting that we obviously had all the
*normal* updates going on too, and the work everywhere else didn't
just magically stop, even if some developers have been distracted by
CPU issues. In the *big* picture, 4.15 looks perfectly normal, with
two thirds of the full 4.15 patch being about drivers, and even the
arch updates are dominated by the arm DTS diffs, not by CPU bug
mitigation.

So the news cycle notwithstanding, the bulk of the 4.15 work is all
the regular plodding "boring" stuff. And I mean that in the best
possible way. It may not be glamorous and get the headlines, but it's
the bread and butter of kernel development, and is in many ways the
really important stuff.

Go forth and play with it, things actually look pretty good despite everything.

And obviously this also means that the merge window for 4.16 is open.
I already have a number of pull requests pending that I will start
merging tomorrow. Hopefully we'll have a _normal_ and entirely boring
release cycle for 4.16. Because boring really is good.

Linus

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