Configuring the 2.6 Linux Kernel

An anonymous reader writes "This article is the first in a series by William von Hagen on using the new Linux 2.6 kernel, with a special emphasis on the primary issues in migrating existing drivers, applications, and embedded Linux deployments to a Linux distribution based on the 2.6 kernel. Bill is the author of Linux Filesystems, Hacking the TiVo, SGML for Dummies, Installing Red Hat Linux 7, and is the coauthor of The Definitive Guide to GCC (with Kurt Wall) and The Mac OS X Power Users Guide (with Brian Profitt)." This looks to be a good series for anyone planning to migrate to Linux 2.6, and having done just that myself, I'll attest to wanting more documentation along the way.

Do it the easy way : Get Manadrake 10-beta2

[Anonymous Coward]

Mandrake 10 will be the first major distro use Kernel 2.6. Download the beta here [mandrakelinux.com].

Easy to install, just download the ISOs, burn to disk, reboot and the installer will appear.

Make sure to REPORT ALL BUGS, unless you want to see the LG incident again.

slackware users out there

[mfivis]

I found this sticky at linuxquestions.org's forums to be most helpful in doing an easy and straightforward 2.6 compile on a slackware system. LinuxQuestions.org [linuxquestions.org]

Re:Misinformation - Misinformation

[Anonymous Coward]

the 'funky X configuration interfaces' you talk about are nothing more than GUI applications

Did you RTFA? The article basically stated some obvious changes, and talked up the new GUI configuration interface as if it was the best thing ever since sliced bread.

Nothing interesting in this article, IMHO. I hope the subsequent articles will be more informative.

Re:They need a tutorial on this stuff?

[zonix]

I just like the config file method. Does this mean that I can keep my config file (for compiling the kernel) when I upgrade to the next stable? (keeping in mind that I have it customized)

Yes, that's what the "make oldconfig" is for. You need to overwrite the .config file first. This goes for the 2.4 series kernels - I don't know if it has changed in the 2.6 series?

z

Re:They need a tutorial on this stuff?

[forlornhope]

copy your /boot/config-2.x.y to the source directory as ./.config and then make oldconfig. It will go through all the old options setting them and present you with only the new options. Its a text only interface, but its pretty simple to choose between y/n/m/? and each option is pretty self explanitory. I think you can also step back a version using the same method, but Im not sure about that.

Re:Do it the easy way : Get Manadrake 10-beta2

[77Punker]

Yeah yeah...Debian has had kernel 2.6 binaries for a while now in apt-get.

Re:They need a tutorial on this stuff?

[PatrickThomson]

Yeah, if you copy over .config and run "make oldconfig" it'll only ask you new questions - could be problematic for large changes, but for little kernel upgrades it's worked fine for me (2.4.22 -> 23 -> 24; 2.6.0 -> 6.1 -> 6.2)

IANAKH, so feel free to correct me.

Re:Usability?

[lokedhs]

Well, nVidia has support for their graphics cards on 2.6 [nvidia.com]. As for the other hardware you'll have to google yourself. The nVidia link wasn't paticularily hard to find.

Re:They need a tutorial on this stuff?

[Anonymous Coward]

by the way, while you're at it, there is an option to have a compressed configuration file included inside the kernel image itself, and to be read from /proc/config.gz ( applies only to 2.6 kernels and some patched 2.4 kernels only )

ITS AN ADVERT!!!

[Anonymous Coward]

This is just a very loosly disguised advert for TimeSys Linux

Nothing any monkey cant work out in about five minutes (and if they cant they should not be cross compiling for embedded devices)

Since most people dont RTFA this isnt a problem, if you are one of the many... dont bother - its S**T

Re:Configure your own kernel

[blackrider]

It wont solve the main problem, but you can enable the /proc/config.gz option in the 2.6 kernel, so you can access the old config at any time through the /proc interface.

Re:2.6 breaks KVM support

[boredMDer]

I've used 2.6.0 through 2.6.2 on my machine with a KVM for a while now, never had an issue.

Probably just a problem with your KVM or setup.

Re:2.6 breaks KVM support

[The Irish Jew]

I've used a KVM w/ both 2.6.0 and 2.6.1 and have had no problems. The trick was to use "IMPS/2" as the mouse protocol instead of "Auto". That, along with your ZAxisMapping option should be all you need to get it to work. Assuming of course your KVM is ps/2.

Re:Default

[Torne]

The default x86 kernel config always used to be Linus's machine; I don't know if this is still the case. =)

Re:Configure your own kernel

[Anonymous Coward]

You can always include almost everything as modules.

Or alternatively you can take a kernel configuration of your favorite distribution and tweak it to your liking. Most distributions will include drivers for all common hardware as modules.

Re:Usability?

[Weird O'Puns]

Kernel 2.6 is very usable and stable. I've been running mm-sources since 2.5.5x and haven't had any major problems with it. There's hardly any need for recompiling packages (there are few exceptions though, mostly packages that install some kind of kernel module, svgalib for example). One thing you must do is to replace modutils with module-init-tools.

Gentoo forums are relly your friend. There are tons of threads concerning 2.4 to 2.6 upgrade, including some howtos.

2.6, X, and stuff

[NixLuver]

The 'GUIFication' of the Linux kernel is interesting, but not mandatory. Make menuconfig still works, so you don't have to have X. Also, most of the bells and whistles related specifically to application space can be de-selected, so runaway featuritis is at least controlled.

The 2.6 kernel is noticeably faster on my dual Athlon 2100+mp, at the user interface; X is faster than I've ever seen it before; the realtime scheduling is awesome.

In short, as soon as you can reasonably do so, I recommend you migrate to the 2.6.x kernel.

Re:Do it the easy way : Get Manadrake 10-beta2

[Anonymous Coward]

Yes, but Mandrake 10 has a lot of other new stuff, that is optimized for Kernel 2.6. Here are some other reasons to try Mandrake 10.

XFree86 4.4 (better GUI)
KDE 3.2
NPTL
Mozilla 1.6
And most improtantly, Improved Usabillity

Kernel 2.6 is like a new engine, but the experiance is a lot nicer when you get a whole new car to go with it.

Re:2.6 breaks KVM support

[Nerant]

There is a 2.6 Input Drivers Faq [kerneltrap.org]. It covers some of the more common issues, including some KVM problems.

Re:Usability?

[Spoing]

1. Is the 2.6 kernel "Usable" yet?

In sum, yes. As with any major kernel update you have to have the matching user space parts or many devices will not work. Required documentation is included with the kernel;

1. README (case sensitive) and

   ./Documentation/Changes (as noted in README)

Keep in mind that if you don't need support for specific hardware -- say, ISDN or PC-Card/PCMCIA -- you can skip updating those packages.

Specific comment: Alsa is now the default sound system, and it needs updated supporting tools if you want to get a peep out of your audio. Point for point comments;

1. By this I mean getting obscure hardware to work such as my USB Midi Interface, -- USB MIDI support is included, though I haven't tried it.

2. and what about proprietary drivers such as Nvidia's, will existing code compiled for 2.4 kernel work? There are updates, and they work fine; install the same way as with 2.4. Check the normal places on Nvidia's site.

3. or will you have to recompile stuff (IPTables for example). Im running a gentoo box. I haven't, though I don't have Gentoo (Fedora Core 1).

4. I've been toying with updating the kernel to 2.6 and I've been hearing that there are a lot of radical changes to the kernel, the performance enhancements are very exciting to say the least. It's better for average use, and low latency apps should work much better (ex: sound processing), though I haven't noticed much of a speed boost. 2.4 was snappy already.

5. But what kinds of headaches am I going to have with a real world (used as a desktop as well as a server) system? Rebooting. Checking the software versions. Looking at all the possible options in the 2.6.x kernel -- though this is much easier with the updated menus in the confiuration screens ('make xconfig' (QT)/'make gconfig' (GTK)).

Normal precautions, nothing special.

Re:Do it the easy way : Get Manadrake 10-beta2

[rokzy]

I've tried beta 2 so the following is simply The Truth, but doesn't mean I won't be modded Troll:

I hate the way Mandrake makes KDE look disgusting whereas SUSE makes it look beautiful, and also functional as opposed to Mandrake's default usless patterns around all the windows.

I couldn't find any links to my drives on the desktop or elsewhere, and so was unable to get the CD out (not counting rebooting or command-line unmounting which are both unacceptable for a modern OS aimed at the public).

the configuration panel seemed nice but very slow and several of the options would cause a crash and the system wouldn't even restart.

so back to SUSE 8.2 for me until the next version with KDE 3.2 comes out.

Re:Configure your own kernel

[Neil Watson]

When you add new hardware that is not needed at boot (e.g not a bood device), simply build the kernel feature to support your new device as a module. Install the module and you are ready to go. No rebuild or reboot needed. You don't throw away config files. You save them for later use. The config procedure gives an option to save your config to an alternate location.

Re:is it so much different than 2.4?

[Trelane]

Speaking from experience (P1 100MHz, no MMX, 16MB RAM, 500MB disk), going from 2.4 to 2.5 was a beautiful, beautiful thing. Sure, it'll give you a ton more performance on a high-end box, but it makes a low-end box much more usable.

One major problem in migration...

[ThogScully]

The foremost problem I had in migration was that SCSI emulation with ide-scsi is no longer used for CD burning. I expect many people making the upgrade will run into a problem with that.

You can use the standard ATAPI ide-cdrom driver now to burn your CDs, but the userspace programs haven't caught up to this in all distros, especially the GUI ones. cdrdao just doesn't work last I checked, and while cdrecord works alright in the newer versions, many GUI frontend burners simply use cdrdao too much to be useful.

Other problems I had were that lm_sensors changed a bit and I didn't find it important enough to upgrade to newer userspace stuff, but anyone who's relying on them for anything will likely want to know that it's changed and upgrades to userspace are necessary. The only other issue, which was fixed by a quick Googling was that the module system is changed and module-init-tools is now necessary for loading and unloading kernel modules.
-N

Re:Do it the easy way : Get Manadrake 10-beta2

[Anonymous Coward]

It's only driver updates. Might be of interest if you run the stock ATI driver (instead of the one from ati.com), but otherwise it's nothing to get excited about.

Re:Do it the easy way : Get Manadrake 10-beta2

[dan the person]

I couldn't find any links to my drives on the desktop or elsewhere, and so was unable to get the CD out (not counting rebooting or command-line unmounting which are both unacceptable for a modern OS aimed at the public).

Did you try pressing the eject button on the CD drive?

I release that might not be obvious for a seasoned linux user, but for the rest of the planet it is.

Mandrake has had supermount for removeable media for a long time now.

Stay with ide-scsi if you want

[michich]

Well, you can still use the ide-scsi emulation in 2.6, although it's not optimal. Recently there have been some fixes to ide-scsi in 2.6, that have made it usable again.

Re:Do it the easy way : Get Manadrake 10-beta2

[waster]

its a little bit more than driver updates
X4.4 includes autoconfguration (bye bye XF86Config) and ipv6, as well as a host of bugfixes.

Re:2.6 breaks KVM support

[Anonymous Coward]

As far as I can tell, there is no way to use a KVM with kernel 2.6 and still have mouse wheel support. It works until you switch away and back to Linux, at which point the mouse goes completely nuts and cannot be revived.

I had the same problem and none of the usual fixes (such as switching to a VT and back to X, ot trying a different mouse protocol) solved the problem.

Ultimately, it was upgrading to XFree86 4.3.0-rc3 that magically solved the problem for me.

Re:Do it the easy way : Get Manadrake 10-beta2

[Jameth]

Slackware has been 2.6 ready since 9.1 Just install 2.6 and your good to go. Mandrake 10 may be the first major distro to ship with 2.6 included, but that's just because Slackware's release schedule was ahead of the kernel, so it added proactive support, as any good distro would do.

kernel 2.6 and gentoo 1.4

[Frogg]

I'm using kernel 2.6.x and gentoo 1.4, and I'm fairly new to linux. All my h/w (nvidia, sblive, adaptec-compat scsi, usb mouse + mp3 player) works very well.

It wasn't as smooth an upgrade as I'd've liked, but, like I said, I'm fairly new to all this.

When I first upgraded, I did get a lot of errors/warnings on boot, but I have since fixed them all.

Ensuring you have the latest versions of hotplug and module-init-tools will help your migration to 2.6, as there are changes to h/w detection and module loading.

Take care when doing make oldconfig from an earlier gentoo kernel - gentoo kernels have had various performance patched in them for some time, but -- if I recall -- these settings didn't all magically migrate across, as the gentoo kernel build flags and the official kernel build flags have differing names for these features between 2.4 and 2.6. Just remember to check all your options with make menuconfig or similar. Some other build flags have changed names too, including stuff for usb devices and (IIRC) framebuffers -- this will probably only catch you out if you're migrating settings from an older kernel.

After building and installing my 2.6 kernel, I also installed the latest nvidia package from nvidia's website, and alsa-lib and alsa-utils (both 1.0.2, from portage)

Also, there are changes to how some system stats/info is handled/reported - ensure you have an up-to-date version of procps, or top might give some cranky info... some tools that monitor memory levels (gkrellm, various gdesklets) will stop working because the output of /proc/meminfo has changed (the first few summary lines have been removed) -- fixes for this don't seem to exist yet.

Other than the meminfo issue, kernel 2.6 hasn't broken anything (that I've noticed) on my gentoo system, and it appears to work very well.

(Oh, kernel 2.6 did cause one of my drives to give warnings about unexpected DMAs every few mins, but that totally fixed itself once I stopped overclocking the CPU. The drive was running slower with a mis-firing DMA, but other than the warnings, no problems occured (YMMV). Something in 2.6 must be more timing sensitive or less tolerant of overcranked h/w speeds. NBD: my system is a few years old, the extra ~20% speed increase cannot is insignificant when compared to speeds of a modern CPU - it seemed a lot at the time!)

Re:2.6 breaks KVM support

[Anonymous Coward]

While you do need to edit the registry to enable it for all sessions you can use

cmd /f:on

Then...

ctrl-f for filename completion
&
ctrl-d for directories

on a per session basis.

2.6 on NForce-based motherboards

[FuzzyBad-Mofo]

If you are upgrading an NForce-based machine to 2.6.x, save yourself some headaches and add "noapic nolapic" to the Kernel append string. I experienced repeatable hard lockups when doing disk intensive I/O until adding those parameters.

Also, NVIDIA's nforce package is no longer necessary. The experimental forcedeth driver in 2.6.2 works quite well in my experience, and apparently an Intel sound driver works for the NForce onboard sound.

See my latest journal entry for my account of migrating MDK 9.1 to a vanilla 2.6.1 kernel.

Re:2.6 on NForce-based motherboards

[motown]

I experienced the same problem and solved it by excluding APIC support in the kernel configuration alltogether.

I recall reading somewhere that disabling ACPI while keeping APIC enabled should also solve the issue. In other words: the problem apparantly only occurs when BOTH ACPI AND APIC are enabled on systems with Nforce2 chipsets.

Wasn't there supposed to be a patch out there fixing this issue already? And if so, why hasn't it been merged in the tree by now? I know, I know, the 2.6 tree is still quite young, but then again: the patch has been around since before the official 2.6.0 kernel was released.

By the way: does anyone know if we're missing out on much by disabling APIC support? Is there any downside to having shared interrupts (performance- or otherwise)?