Linux Kernel 4.5 Officially Released

prisoninmate writes: Yes, you're reading it right, after being in development for the past two months, Linux kernel 4.5 is finally here in its final production version. It is internally dubbed "Blurry Fish Butt" and received a total of seven RC builds since January 25, 2016. Prominent features of Linux kernel 4.5 include the implementation of initial support for the AMD PowerPlay power management technology, bringing high performance to the AMDGPU open-source driver for Radeon GPUs, scalability improvements in the free space handling of the Btrfs file system, and better epoll multithreaded scalability. The sources are now available for download from kernel.org. Update: 03/14 13:24 GMT by T : Reader diegocg lists some other notable features (a new copy_file_range() system call that allows to make copies of files without transferring data through userspace; support GCC's Undefined Behavior Sanitizer (-fsanitize=undefined); Forwarded Error Correction support in the device-mapper's verity target; support for the MADV_FREE flag in madvise(); the new cgroup unified hierarchy is considered stable; scalability improvements for SO_REUSEPORT UDP sockets; scalability improvements for epoll, and better memory accounting of sockets in the memory controller), and links to an explanation of the changes at Kernel Newbies.

Comments

Still pretty crusty on laptops

[jones_supa]

I recently did a quick survey in Reddit on people's experience on suspend/hibernate, and I may summarize it simply by saying that Linux is not the best performer in this area. :D It's a shame that such an important laptop feature works so poorly. Some might say that it's because OEMs do not "support ACPI spec properly", but in practice most PCs don't... It could be more practical to just find the patterns that Windows uses, and imitate them.

One really weird thing is also that backlight adjustment requests are sent to both ACPI and GPU, which causes double backlight adjustment events on many laptops.

People fight about SystemD, various open source licenses, differences between DEs, filesystems, but at the same time there's these fundamental problems which should get way more attention. Sometimes it feels like we are in a house arguing what kind of wallpapers bring the best experience, while that same wall is infested with mold inside.

Some people still talk like this is supposed to be the hi-tech kernel that breathes new life to my PC. Are they blind to all this stuff happening?

Re:Still pretty crusty on laptops

[Kjella]

General issues are everybody's problem. Issues with one particular piece of hardware is:

a) Not really the problem of anybody else
b) Not something most people can reproduce
c) Not anybody's job

If Dell delivers laptops with Linux preinstalled, then it's their problem, they got the hardware to reproduce it and they got paid people working on it. If $random_user installs $random_distro on $random_laptop, well the manufacturer doesn't care. And while there's always a few people working to make Linux run on everything, they're few and they can't go around buying laptops just because and there's new models all the time. Red Hat will work on supporting the servers that RHEL runs on, they won't generally work on random hardware. And the kernel is mostly driven by paid development, other hardware is very much in the "you want support for that? great, submit a patch and we'll review it" mode.

Some might say that it's because OEMs do not "support ACPI spec properly", but in practice most PCs don't... It could be more practical to just find the patterns that Windows uses, and imitate them.

Says no person who has tried imitating an undocumented binary blob ever. Basically manufacturers just bang the code until it stops crashing, unless you can replicate it exactly which is hopeless in practice you're going to run into random issues. And random issues here aren't just glitches, they're usually crash/hang bugs. I'm sure a lot could be done if you brought the right people together with the right hardware and gave them some money to work on that. But I don't really see who'd do that, because it's not just free time and there's no profit in it.

Re:Still pretty crusty on laptops

[Gaygirlie]

People fight about SystemD, various open source licenses, differences between DEs, filesystems, but at the same time there's these fundamental problems which should get way more attention. Sometimes it feels like we are in a house arguing what kind of wallpapers bring the best experience, while that same wall is infested with mold inside.

You're setting up a false dichotomy, there: the fact that some people are designing filesystems or DEs or Systemd or such isn't necessarily away from progress on the ACPI-stuff and the likes. Not everyone knows enough about ACPI, for example, to be able to contribute anything useful, so them working on something else doesn't hinder the progress on the ACPI-stuff in the least.

Also, not everyone agrees with your priorities, like e.g. a lot of people deem work on filesystems more important than getting ACPI totally right -- not everyone needs working suspend, not everyone is running Linux on a broken laptop, but filesystems? Improvements in them are likely to have a much wider area of effect.

Re:Still pretty crusty on laptops

[Bert64]

Suspend and hibernate works just fine on laptops designed to run linux (e.g. chromebooks), the same can be said of macosx - suspend and hibernate is perfectly reliable on apple laptops, but is usually flakey on a hackintosh.

Linux already has various kludges to emulate the nonstandard way in which windows handles power management, but laptops also often come with customised model-specific drivers so even if you run windows you often still have problems if you run the default drivers or drivers for the chipsets rather than the specific laptop model.
The lower end laptop makers also make things difficult for users by varying the hardware in the same model, when looking at laptops recently i was told that a given model could have any one of 3 different wifi and ethernet chipsets, and that i wouldn't know which until i physically took delivery of the laptop... They will guarantee that you get "an 802.11ac wireless card" and "a gigabit ethernet", but the performance, range, stability or cpu usage can vary wildly between chipsets as can compatibility with linux or other systems and even (albeit quite niche) features like wireless monitor or master modes are not available with some chipsets.
The chipsets in use for various components were always an important factor for me when deciding what to purchase.

Yes it's a huge nasty mess!

Re:Still pretty crusty on laptops

[Viol8]

Ah , the old "Only kernel developers can complain about an issue, users should shut up and say nothing" school of thought. I wondered how long it would be before some mouth breathing window licker said it. Congratulations, you are that idiot.

Re:Still pretty crusty on laptops

[OzPeter]

If your hardware has problems, what are you contibuting to fix the problem? whining? *tumbleweeds*

Ahh .. victim blaming at its finest.

Re:Still pretty crusty on laptops

[OzPeter]

the same can be said of macosx - suspend and hibernate is perfectly reliable on apple laptops, but is usually flakey on a hackintosh.

Yeah .. works totally fine in OS X on my MacBook Pro.

But I can't seem to find the configuration controls for the Computer Bag Heater function. You know the one .. where you put the computer to sleep, close it up, put it in your bag, and then an hour later you feel how warm everything still is and realize that the damn computer is still running.

Re:Still pretty crusty on laptops

[fuzzyfuzzyfungus]

It's worth noting, in terms of 'difficulty of dealing with undocumented binary blobs and ACPI in general', that Microsoft's own designed, developed, and blessed Surface Pro and Surface Book products have been dogged by power management issues; and that's with hardware hand picked by Microsoft, an OS built by Microsoft, and drivers and firmware either written by Microsoft or written for Microsoft by vendors who do most of their driver development work to support Microsoft OSes.

Obviously "but look at the other guy!" isn't an argument against the fact that Linux on laptops indeed has issues; it just provides some perspective on what a ghastly mess PC power management is. If Microsoft's own "Our OEMs are making us look bad, so here's a kick in the ass and a reminder of what kind of products we want in the PC space" product can't power-manage properly, that doesn't imply positive things about the difficulty for the Linux kernel team of getting power management to work correctly on some random vendor's apathetic attempt to shove a laptop out the door for as little money as possible.

Re:Still pretty crusty on laptops

[KGIII]

A distro's support mailing list recently had a comment about this. It wasn't even trolling, just some new guy.

The response, and only response, that I saw was someone who said, "With today's SSD and hardware being so fast, I don't even need it. It's a useless feature anyway."

Which is emblematic of my largest distaste for the community. It's certainly not something I have against Linux, the kernel, but that is rather atypical for the many communities surrounding it.

I almost responded, "Nope, it works fine for me." (It really does.) But, fortunately, I don't drink any more and I'm generally not an asshole. Well, not always.

I decided that I'd scroll down prior to hitting submit. *sighs*

Re:Still pretty crusty on laptops

[IgnitusBoyone]

This was a feature on my Mint Laptop last winter when my car heater went out.

Re:Still pretty crusty on laptops

[Barsteward]

Suspend/hibernate has always been down to the manufacturer not following the standards properly but following what Microsoft Windows needs because it doesn't follow standards. They bodge it to make sure WIndows works

Re:Still pretty crusty on laptops

[Gadget_Guy]

The ones that have a right to complain are paying customers

And who are you to actually say that? You can't even be bothered creating an account on Slashdot and yet you feel you can tell logged-in users what they can and can't say.

Nobody has to shut up just because you say so. Now whether the kernel developers actually listen to the complaints is up to them, but they can't dictate what their users say. Nowhere in the GPL do we sign away our right to free speech if we don't pay someone money.

Re:Why Support Drivers in Kernel ?

[Anonymous Coward]

Linux does not come with stable driver interface, so drivers supplied by vendors would rot quickly. It's more practical to just bundle everything with the kernel, update the driver interfaces there, and recompile. However this has the additional benefit that one does not have to hunt drivers around Internet, so if you have the most recent kernel, you also have all the most recent drivers.

Re:Why branch when you don't intend to support it?

[WarJolt]

Are you seriously still complaining about this?

The last odd kernel was released in 2003. In 2.6 stable and unstable merged. Kernel 3.0 wasn't even a drastic change.
https://lkml.org/lkml/2011/7/2...

Between 2.4 and 2.6 linux was drastically overhauled. We really don't need separate non stable versions anymore. Plus version control is far better now.

Re:New name

[jandersen]

It is internally dubbed "Blurry Fish Butt"

Rumor has it that the next kernel will be named "Lennart's buttery balloon knot".

Oh dear, I definitely feel old age sneaking up on me; I just don't find these names funny any more. If ever I did. I'm all for having a sense of humour, but it would be refreshing if it wasn't always stuck up our own backsides. Can't we raise the level a bit? (Groan, I shouldn't have said that - now it's going to be about tits instead, isn't it?)

Re:Why Support Drivers in Kernel ?

[Gaygirlie]

You are confusing things. The drivers are part of the kernel's sources, but you can either build them compiled-in or as modules that are then loaded when needed.

Re:Why Support Drivers in Kernel ?

[Dutch Gun]

Thanks for the link. I actually read through that, and while some of the arguments were certainly valid, some of them sounded an awful lot like simple justification for how Linux chooses to do things. For example, rapidly changing internal API interfaces is something of a self-fulfilling prophecy when you assume you can just change the interface of any drivers for which you have the source. He acknowledges that it would be more work to maintain older, depreciated interfaces, and claims that they couldn't impose such a burden on volunteer programmers. It may be true in some cases, but that argument seems a little weak with the knowledge that these days most contributors today are actually paid by a corporation for their work on the kernel.

This sentence is of particular note: "...get your kernel driver into the main kernel tree (remember we are talking about GPL released drivers here, if your code doesn't fall under this category, good luck, you are on your own here, you leech)..."

This attitude is both the strength and weakness of Linux. It works FOR Linux as an open platform, but certainly AGAINST it as a commercial one, if a manufacturer doesn't wish to open-source their drivers - and that unfortunately includes video card manufacturers, which is also a major issue for Linux. If a commercial vendor feels unable to release open source drivers for their proprietary hardware for whatever reason, then Linux is simply *never* going to work reliably on their hardware.

More importantly, because client machines tend to be much more reliant on the subtle interfaces and behaviors of many complex drivers (headless servers don't have to worry about nearly as much), I believe that this philosophy is a large part of why Linux remains something of a second-class citizen on the desktop. I'm not saying this philosophy is necessarily wrong, but I think it's important to understand that it definitely comes with some tradeoffs.

Re:Why branch when you don't intend to support it?

[Kjella]

As I recall, the older versions of the kernel added some features and offered others as third party patches. The 2.0.x, 2.2.x, 2.4.x, and 2.6.x branches were supported for a very long time, (...) This was a very successful development model for over a decade and I don't understand why that's changed. Arguably, it would require fewer work since there wouldn't be as many branches to maintain.

Actually it wasn't. Distros were massively cherry-picking from the odd-numbered branches creating huge variations from the stock kernel, creating strange bugs and making the big jumps was a huge pain because the more relaxed requirements to put it in a development branch led to poor quality. Linus tightened ship and basically said do development in your own branch, when it's ready merge it to the released kernel and ~2 months after the merge window closes it'll be released instead of years like the old kernel. No more hodge-podge development kernels full of half-assed changes. It got distros to work more on the upstream kernel than their own variations, leading to more manpower and higher quality in the core project. It was a great success.

Re:New name

[KGIII]

I don't think Lennart's got tits. But, he does have nipples. Lennart's Nubian Third Nipple...

Hmm... Nope, still not funny. Maybe they'll aim higher?

Re:Why Support Drivers in Kernel ?

[fuzzyfuzzyfungus]

One can obviously debate the value of this; but my impression is that, while in an ideal world they'd like to be able to support more hardware, when it comes down to it the Linux project really isn't interested in just providing a cheap OS for people to put on top of their giant heap of binary blobs. They certainly aren't as hardline as the FSF; but even the 'engineer-pragmatist' types see binary blobs as an impediment to their work(that's why the kernel taint flag exists: if your system crashes, you have a potentially interesting bug report; but if it was 30% Nvidia blackbox by weight at the time, they don't want to waste their time shooting in the dark).

Re:What about 2.6.32?

[Barsteward]

no doubt you've been testing the next LTS version in the mean time, you can move to that

"Lennart's Tiny Head"

[Anonymous Coward]

I don't think Lennart's got tits. But, he does have nipples. Lennart's Nubian Third Nipple...
Hmm... Nope, still not funny. Maybe they'll aim higher?

"Lennart's Tiny Head" : Linux 4.7, includes the systemd NFSA io secheduler, the systemd NFSA job scheduler, as well as the systemd "do it all as init 1" replacement for the Linux graphical subsystem. Enjoy.

Re:Well????!!!111

[Zaiff Urgulbunger]

Yeah, but does it run Linux?

As of last week, "Does it run MS SQL Server?" is the new "does it run linux".