Linux Kernel 2.6.31 Released

diegocgteleline.es writes "The Linux kernel v2.6.31 has been released. Besides the desktop improvements and USB 3.0 support mentioned some days ago, there is an equivalent of FUSE for character devices that can be used for proxying OSS sound through ALSA, new tools for using hardware performance counters, readahead improvements, ATI Radeon KMS, Intel's Wireless Multicomm 3200 support, gcov support, a memory checker and a memory leak detector, a reimplementation of inotify and dnotify on top of a new filesystem notification infrastructure, btrfs improvements, support for IEEE 802.15.4, IPv4 over Firewire, new drivers and small improvements. The full list of changes can be found here."

Comments

Linux audio

[Anonymous Coward]

there is an equivalent of FUSE for character devices that can be used for proxying OSS sound through ALSA

That quote shows how much of a train wreck Linux audio is.

Re:Linux audio

[nimbius]

amen. OSS, alsa, pulseaudio, for christsake just give me sound that works without having a million handler processes.

OSS was okay.

Re:Linux audio

[bcmm]

amen. OSS, alsa, pulseaudio, for christsake just give me sound that works without having a million handler processes.

So just use ALSA!

The situation on Linux is that there used to be OSS, and now there is ALSA. ALSA works fine, for pretty much everybody. There are a few legacy apps which use OSS because no one is updating them, and obviously, it would be nice if they would play nice. Pulseaudio is a bit strange, but nothing requires it's use, and IMHO there is no real reason for it to be used unless you want to do somewhat strange things (that you generally can't do on any other type of OS). Don't use pulseaudio if you don't want to; if your distro forces it on you, use a sane one.

This scary graph and related ideas tends to get mentioned in connection with this: this conflates libraries, sound servers, and drivers to some extent. One could draw a similar graph for windows, featuring programs using the Quicktime library, the WMP library, MME, DirectSound, WASAPI and various other APIs and libraries (and I haven't even gone into the changes to the audio driver model). WMP would have plenty of in arrows from applications using its libraries, and plenty of out arrows because it supports more than one API. And don't forget that there are still legacy applications which need to be the only app playing audio, just like on Linux.

Here is why I can't be bothered to learn enough about the driver layer to give examples: "UAA is intended to be a complete replacement for developing WDM Audio Drivers; however, in some cases it may be necessary for an otherwise UAA-compliant audio device to expose capabilities that cannot be done through UAA. Windows will continue to fully support audio drivers that use the PortCls and AVStream drivers.

Audio technology has evolved, lots. Having backward compatibility requires that things get slightly complex. Everybody is doing this. I think Linux is doing it rather well, although certain distros make some odd choices.

OSS was okay.

OSS made it impossible to play more than one stream at once on a lot of hardware.

Re:Linux audio

[someone1234]

For some time Alsa was the "new tech". Now PulseAudio. By the time it stabilizes, there will be something else.

Re:Linux audio

[jw867]

What bothers me here is that I read "Oh, change this, do that turn this knob and sound will work for you." Then it works until there's a new kernel update (I use Ubuntu) and it breaks again. Or it just stops working after too many applications use it.

Then you read how fabulous PulseAudio is and how wonderful it is, but it just plain does not work. By working, it should work every time, all the the time without knob turning. It's embarrassing that in this area, Windows 95 is superior to Linux in almost every respect.

All this effort is put into chrome polishing the kernel for faster SMP with 64 CPU systems and the dang box can't even play music without having some sort of brain failure.

Re:Linux audio

[Per Wigren]

PA is for desktop audio. For pro audio production you'll run JACK and have PA output its audio to JACK instead of directly to ALSA. That way your pro audio apps will get their super low latency and all of the apps that can get away with 50ms latency will play through PA to JACK. You get the best of both worlds.

Re:Linux audio

[walshy007]

OSS made it impossible to play more than one stream at once on a lot of hardware.

With a standard configuration, alsa does also, you have to load the dmix module in your config to act as a software mixer on cards that don't do hardware mixing (most on board bits).

This is where the userspace demons enter it all, most of them just started out as another layer that does software mixing, but every man and his dog came up with his own invention.

As for just using alsa, that's great if you don't mind not having certain functionality, some of the sound demons do add some nice features (jack is the only one I've found worth using though). It could be argued the driver layer shouldn't have to deal with some of that advanced functionality though, another reason why these demons were made.

Re:Linux audio

[Hatta]

it is a good API and it IS the future of Linux desktop audio,

It may be a good API, but it's not a good implementation. But yeah, I can agree that glitchy, high latency audio is the future of Linux desktop audio.

Re:Linux audio

[impaledsunset]

"Pretty much every distribution has standardized on Pulseaudio" is the very definition of regress. What you said was getting better and better? I installed Debian unstable on my laptop, with KDE desktop, and it also installed and enabled this trainwreck called "PulseAudio", which serves as only purpose to disable the audio of an already working system. Sound has worked for me in Linux since forever, never had any problems with it until PulseAudio came around.

During the early days I had been using a sound card with hardware mixing. Back then even Windows wasn't coping well with several streams and a card supporting only one, so what OSS offered back then was good enough for me, and on par with other operating systems. Then came ALSA, which offered dmix and dsnoop to do it software. Now, dsnoop has never worked for me, but I don't know any other operating system that supports such a feature so I guess I don't have much ground to complain.

Then PulseAudio came around, and that is the first time when I had any problem with sound on Linux. Sound started to be skippy, jumpy, choppy, and not working in some applications. Why would anyone think that PulseAudio would be a good idea? Now, don't get me wrong, I like PulseAudio, I even use it for some tasks. Namely playing music from my laptop on the soundcard of my desktop. But thanks to the brilliant idea that PulseAudio should be used everywhere I couldn't really do that anymore, because I had to eradicate PulseAudio to have sound again, so I couldn't use it for *my* needs. Fuck me.

Disclaimer: I'm not sure I'm chronologically correct above, the sound might have been in a better state in Windows than in Linux during OSS times, I just mean that I was already used to being able to play only *one* sound at a time when I first came to use Linux, so it seemed pretty normal thing to me.

Re:Linux audio

[TheRaven64]

You don't need them with OSS on FreeBSD and Solaris (for example), or on Linux with the out-of-tree OSS 4 implementation because they supported sound mixing so the kernel actually does what it is meant to do - lets the userspace apps ignore the differences between hardware implementations. The mixing is either done in hardware if the hardware supports it or software if it doesn't.

Re:Linux audio

[TheRaven64]

OSS 3 did on FreeBSD too. It's not a technical limitation of the hardware or the interfaces, it's a symptom of the NIH mentality on Linux. FreeBSD has supported software sound mixing with OSS since around 2000. I you want to play sound, just open /dev/dsp and write data there (on FreeBSD 4 and earlier you had a different device node for each virtual channel, so you needed to tell xmms, aRts and so on to each use a different one, with 5 and later the kernel does this for you). The problem with Linux sound is that, when 4Front decided to make the next OSS release proprietary, they decided to deprecate it in the kernel, rather than just maintain the open source fork. The FreeBSD folks kept developing their version and adding features, maintaining parity with the proprietary version. Now OSS4 is open source it's merged into OpenSolaris and FreeBSD has pulled in the relevant features ALSA looks both dated and nonportable, but the Linux devs have invested a lot in it so they don't want to throw it away.

Re:Linux audio

[bluefoxlucid]

What IS the PA latency, and the Jack latency? Jack seems idiotic; just use the sound card directly. Seriously, consider this: JACK -> ALSA, you can go directly to ALSA anyway (I haven't had a sound server for years). Do the mixing in your application and output it to ALSA. If real-time performance is an issue, don't run multiple apps at once. Record separate tracks versus a (monitored) metronome(!) when doing music, and then merge them with Audacity or GLAME.

"Professional" audio amateurs seem to all be n00bs, using their recording device (computer) for playback whereas real "professionals" use monitors, metronomes, visual cues, and master tracks. You monitor your metronome, monitor yourself, monitor the playback track, whatever; and record a separate track. Then later you digitally merge those together. QED. Whatever stupidity relies entirely on your computer being able to low-latency its way out of a paper bag for you to get any work done is a huge engineering error.

Re:Linux audio

[diegocgteleline.es]

You don't need them with OSS on FreeBSD and Solaris (for example), or on Linux with the out-of-tree OSS 4 implementation

You don't need them in ALSA either, because dmix is implemented in the ALSA library, not as a userspace daemon.

It's amazing the increible amount of FUD that has been spread about these topics...

Re:Linux audio

[Desler]

A bit buggy under certain conditions, yes, but that will be fixed in the future.

Except this is the exact excuse we get countless times when audio, video, etc don't work in Linux. Just give us more time! We swear it'll work in the future! Then you wait 6 months and all that previous work is scrapped and something new is built. Then we're told again: Just give us more time! We swear it'll work in the future! Lather, rinse, repeat.

IPv4 over Firewire?

[0100010001010011]

I guess I really wasn't into linux until the last 3-4 years, but hasn't OS X done this since the start? And I think my XP machine at work tries to use Firewire as a network adapter.

What took so long, honest question.

Re:IPv4 over Firewire?

[uhmmmm]

I haven't looked at the official changelog or the code yet, but I'm just as confused as you about that item. Moreso perhaps, as I have used IPv4 over firewire with two linux machines before. That was probably 5 years ago or so.

Re:IPv4 over Firewire?

[muckracer]

Networking over USB would be awesome. Link 2 PC's with USB cable and voila! Hell, even being able to mount an internal drive that way on the other machine would be cool. Anything like that in the works (haven't checked)?

Re:IPv4 over Firewire?

[Anonymous Coward]

From the changelog

*The new firewire driver stack is no longer considered experimental, and distributors are encouraged to migrate from the ieee1394 stack to the firewire stack
*Added IP networking to the new FireWire driver stack

It does add up. It's just added to the new stack, old stack has it already.

Re:IPv4 over Firewire?

[Lemming Mark]

How was the parent modded troll, it's completely valid!

It's a good idea. There have been networking over USB devices (by which I mean plugging both machines USB ports into the device, not "merely" a USB ethernet adaptor). The problem with doing this with USB, rather than Firewire is that USB has a really strong concept of "host" and "device". The cables are made to only plug into certain combinations of endpoints because, sadly, only certain combinations of endpoints can possibly work. You can't plug the host controller of one PC into another, since they're only expecting to talk to devices, not another controller. This is in contrast to Firewire, which is peer-to-peer and (in principle) anything could talk to anything over it.

The unfortunate consequence is that you don't just get to do networking over a nice, cheap cable as you do with Firewire. You actually need a little device box in between so that both hosts can believe they're talking to a peripheral, not another host. This approach, on its own, wouldn't let you plug in "remote" devices either so you'd have to set some other protocol up (plenty of existing options here) to talk to devices at the other end. You have to be a bit careful because most devices would barf horribly if there are multiple users - uncontrolled shared access to a disk device is a good way to lose all your data, for instance.

Although it's fun to do IP over Firewire, I'm not familiar with exactly how it's implemented. What intrigues me is the prospect of running increasingly sophisticated high-performance protocols over Firewire. As I understand it you can basically get remote DMA access to the "other end's" memory. This obviously has severe security implications but it could be quite nice in a mutually-trusting cluster. There are various protocols (e.g. used by Infiniband) for having communications over remote DMA. I wonder if anyone could put together an "infiniband lite" that just ran over Firewire. It'd be cool, though I don't know if it would be particularly useful ;-) (plus it would lack the user accessible networking Infiniband has)

Re:IPv4 over Firewire?

[fuzzyfuzzyfungus]

For tape-based systems, or for situations where a chain of components are expecting a DV stream to be arriving on schedule, you really can't beat firewire. And, for that reason, nearly any PC being used for DV editing will have firewire onboard. Nicer motherboards have it standard, PCI/PCIe expansion cards are cheap if yours doesn't.

However, the trend in camera tech, at least at the consumer level, is making that increasingly irrelevant. Flash and HDD based camcorders are gradually devouring DV camcorders in the lower end market. Pretty much all the HDD or flash based cameras(at least the ones that cost less than the computer they are connected to) just show up as USB mass storage devices, with one or more video files on them. Drag and drop and go. Unlike DV, where the transfer requires that X megabits per second make it from point a to point b, on time, or you'll get glitches, mass storage just requires that all the bits get from point a to point b before the user gets bored. USB still isn't quite as good as firewire at doing that; but the difference in performance is small, and the difference in price/convenience is large.

Once you get away from the real time streaming requirements of DV, to which firewire is well suited, transferring video is just a special case of connecting an external hard drive. Firewire is better there; but only modestly, which isn't really good enough to survive on the price sensitive end of things.

Re:IPv4 over Firewire?

[Hurricane78]

[...] only certain combinations of endpoints can possibly work. You can't plug the host controller of one PC into another, since they're only expecting to talk to devices, not another controller.

Not so with Linux. You can enable the "USB gadget" driver in the kernel. Now if you have a device connector in your system, it can act like any other device. That is how Linux on small devices connects to their hosts via USB. And actually, the way they communicate is plain and simple TCP/IP. :)

Re:i'd just like to

[Lord_Frederick]

Give it up already, Richard.

70% drivers!

[millwall]

Lots and lots of driver work. Over 70% of all of the 2.6.30 to 2.6.31 patch is under drivers/, and there's another 6%+ in firmware/ and sound/. That's not entirely unusual, but it does seem to be growing. My rough rule of thumb used to be "50% drivers, 50% everything else", but that's clearly not true any more (and hasn't been for a while - we've been 60%+ since after 2.6.27

I personally think this is a real pity. So much time is being spent on getting drivers implemented that new features and other kinds enhancements are being pushed back.

Re:70% drivers!

[von_rick]

Enhancements should come as a part of the OS, not the kernel. The main function of a kernel is to get along with all the hardware devices on the system. Drivers should be given a high priority.

Re:70% drivers!

[Timothy Brownawell]

I personally think this is a real pity. So much time is being spent on getting drivers implemented that new features and other kinds enhancements are being pushed back.

I would assume that the people writing drivers and the people doing core stuff are not the same people, so there's no "pushed back". Ideally you'd have driver writers employed by all the various hardware manufacturers, while core stuff likely only interests a much smaller group of companies that live higher in the stack (probably just system and support vendors).

Re:70% drivers!

[walshy007]

Not really, the driver people aren't really the same as those who would be researching new and exciting ways to do what we already do. For quite a long time now driver development has been the majority of what the linux kernel development is.

Of course, every now and then they make something new like mac80211, but all that really achieves is more efficient code re-use and testing, which is always good but is still just driver development.

All the simple things an operating system kernel has to do hasn't changed over the last ten or so years, just the hardware has. Operating system theory was pretty much perfected back in the 60's

Re:70% drivers!

[MrHanky]

What evidence have you got that suggests driver development means other development is pushed back? Do you think the EXT4 developers take time off to write device drivers?

Lots of driver development means Linux has lots of driver developers. That probably suggests that hardware manufacturers actually try to get their stuff supported.

Re:70% drivers!

[Anonymous Coward]

The fact that, with a modern Linux distro, I can plug in pretty much any hardware at least a year old and have it just work no questions asked is a pretty damn spiffy feature.

Re:70% drivers!

[schon]

I'd argue that drivers should be modular and have no business being directly in the kernel in the first place - but that's just me.

$ find /lib/modules/2.6.27.7-smp/kernel/drivers/ -type f|wc -l
1499

Looks like you're in luck!

Re:70% drivers!

[MBGMorden]

Great - now if I compile these lovely drivers will they work on my buddy's (or more importantly, a user's) system running kernel 2.6.1? 2.6.22? 2.6.31? 2.4.5?

Dividing the source and binary out into separate files doesn't make it modular. The infrastructure to move the binaries around needs to be in place so that a driver can be loaded with little regard as to kernel version.

Re:70% drivers!

[Kjella]

I'd argue that drivers should be modular and have no business being directly in the kernel in the first place - but that's just me.

I don't anyone ever argued that drivers should not be modular, in fact that's why there's kernel modules. I'm guessing you're talking about one of the two general flamewars:

1) Monolithic kernel or microkernel
2) Stable ABI for drivers

The first is about making the kernel into a big message-passing daemon, which it turns out has a performance penalty and ultimately doesn't have big enough benefits because a kernel panic and a major subsystem hang/crash both are ugly and if the hardware is left in a borked state it might not really help.

The other is a stable ABI, which has been suggested about 234,533,458 times to date. My only real comment to that is that seeing how crappy many Windows drivers are, do you honestly want them making blobs for a 1% operating system which will get about as much priority, support and bugfixes? Drivers based on specs or donated source almost always suck less.

Re:70% drivers!

[PitaBred]

Keeping binary compatibility limits infrastructure improvements that can be made. You're limited in what you can do to the kernel because of drivers that are sitting out there that expect binary compatibility. If we have drivers that can be loaded with little regard to the kernel version, we get into the quagmire that is Windows, where devices over 7 years old have a low chance of working. My scanner hasn't worked in Windows since XP SP1. It still works perfectly in the brand-spankingest new Linux distros.

Re:70% drivers!

[JohnFluxx]

Far more likely is that companies will behave exactly like they do in Windows - not bother updating their drivers for new versions. There is a lot of old hardware that simply doesn't work in Vista etc because there's no incentive for the company to fix the drivers.

Whereas if it's in the kernel, all the drivers can be fixed at the same time.

Re:70% drivers!

[coolsnowmen]

Insightful?! You couldn't be more clueless.

How do you propose to fix the driver problem? The only way that gets fixed is when every hardware manufacturer writes their own drivers. That would only happen if Linux attained something like 10% market share.

In recent history (the last year or two) the majority (50.1-60%) of all commits to the kernel are drivers/driver update.

Also you forget that there isn't some company that dictates what work gets done on the kernel. There are many developers who work on areas they are want to work in. Are you telling me that linux should reject the FS brtfs because there is a non-name piece of hardware that isn't working yet?

Most kernel features will not directly effect us like driver issues.

Wrong again, My new hardware which I bought off newegg last week works fine in linux (yes I do a quick google search to make sure anyone isn't bitching about something major not working, but anyone who uses linux knows to do that). Because it works, any feature such as a file-system, scheduler improvement, or desktop memory management in low memory situations will improve my experience much more than adding a driver that I won't ever need or use.

Re:70% drivers!

[amorsen]

That would make it easier to manage as the number of them increases.

One of the great advantages of Linux is that improvements can be implemented for lots of devices at once.

I guess a lot of manufacturers will release binary-only drivers, but even if they are buggy, that doesn't leave in any worse state than we are already - those manufacturers aren't releasing drivers for Linux in the first place.

It means people will look at the packaging, notice that it says Linux support, and then find out that it doesn't actually work, and will then blame Linux. Manufacturer-written drivers are fairly universally crap.

Re:70% drivers!

[amorsen]

There may have been a driver problem years ago, but today the problem is pretty much limited to graphics. And DVB, but the competition is doing just as badly there. Overall, Linux driver support is more complete than at least that of Windows Vista.

Yo dawg

[Lemming Mark]

We heard you like your audio to work, so we put a sound API in your sound API, so you can have silence whilst you listen!

Using CUSE for sound devices is The Right Way

[Lemming Mark]

Before we all moved on to worrying about PulseAudio it was traditional for us to complain about legacy apps using OSS, the difficulties associated with wrapping them, the nastiness associated with OSS emulation being implemented in the kernel, etc. Those apps won't have gone away.

Previous attempts to emulate OSS using ALSA have included the aoss tool, which I believe did some mildly ungodly tricks to intercept calls that would usually go to the OSS APIs. It didn't always work, for me, as it depends on what the (often weird and proprietary) app is doing to access the OSS API in the first place. PulseAudio has to provide a tool to help you redirect legacy OSS apps to talk to PulseAudio instead. It's all Made Of Ick.

CUSE (character devices in userspace) allows a userspace program to provide a character device node in /dev and implement it using custom code, rather than relying on an in-kernel driver. When apps open the device node they'll *really* be talking to the userspace daemon implementing the device emulation, rather than to an in-kernel driver (though, of course, the kernel will be involved in relaying the communications through the device interface). This is very similar to what FUSE does for filesystems. The neat thing here is that weird tricks to catch OSS accesses by applications are not needed - the OSS device can simply be "faked" by the real sound daemon. Because it's implemented at device level, it doesn't matter what nasty hacks the OSS application is doing to access the soundcard - you'll *always* be able to grab its sound output from the fake device and do the right thing. No more running legacy apps with an OSS-related wrapper - and no more having the wrapper fail to work!

The end result should be that sound Just Works, even for awkward proprietary apps. CUSE will not automagically fix this on it's own, though - we need to wait for the sound daemons like PulseAudio to catch up and implement the emulation. This might also allow OSS emulation to be removed from the kernel, which AFAIK also supports some variant of OSS-on-ALSA.

Yay!

[British]

Improved acronym support!
Numbers higher than the last version!
greater infusion processor link array warp drive systems!

Support for what?

[saleenS281]

Support for what? A quick search of newegg tells me I can't buy a motherboard, add-on card, or peripheral that supports USB 3.0 today. What exactly was windows 7 going to support? An unreleased chipset?

From your own article:
Jeff Ravencraft of Intel said that he expects the final specification to be announced in San Jose, Calif., on November 17.

Wait, so I'm supposed to be upset that Microsoft didn't ship experimental drivers for an unratified standard in their new OS?

Re:Support for what?

[jbeaupre]

Don't be upset with MS, be happy for Linux. In fact, with support built in, Linux will frequently be used to develop and test the hardware. So some of the early USB 3 products will be de facto optimized to run with Linux.

Re:is btrfs ready for regular desktop use ?

[anonieuweling]

http://btrfs.wiki.kernel.org/index.php/Main_Page has the info, answers, etc

native xfi support

[hyperion2010]

Finally ALSA adds in kernel support for creative X-Fi after 4 years, fuck creative.