What's the "diff" kernel's from different distros, Vanilla vs Redhat Ubuntu Scientific

Hi
Hopefully this is not a stupid question but what makes the same version of a kernel from various distros different? I mean, is it the kernel that makes the distro more reliable, or the distro that makes the kernel stable? Since SL is known as stable, is this due to the kernel primarily or to the other stuff like the modules and applications that are tested to run with the kernel in question. I would guess that SL is stable due to a variety of reasons - but is there a real difference between let's say 2.6.39.1 from SL, Redhat, Ununtu or other distro's seeing that they all come from the same source in the end? Why would I use a kernel from koji only - could I use a kernel from somewhere else - like a vanilla kernel - would it make much of a difference?

The way I understand it is, the linux kernel is all the same but the patches, functions.kernel modules and the way they are compiled are different from one distro to the next.

Hi AndrewSerk :-)
I read that to get the fedora 12 kernel you would go to mirrors.fedoraproject.org and and click on a link to get the source kernel from there but you went to a koji site to download the kernel. Why get the kernel from there instead of the mirrors site and how would one find out about other sites not listed on the mirrors.fedora.org site?

I guess it's because the site is for rpmbuild or is there another reason?

Koji is the build system. Packages are built on koji and uploaded to bodhi. Once in bodhi they are tested by others and given a karma rating. When a package gets a good karma rating it is then pushed to a repo. Bodhi is basically a QA .


More info https://fedoraproject.org/wiki/Bodhi
https://admin.fedoraproject.org/updates
http://fedoraproject.org/wiki/PackageMaintainers/UsingKoji

I have just got in a habit of using the build system as that is the first place a package becomes available.

PS> you probably don't want a F12 kernel as F12 is EOL (end of life) and no updates or patches have been made/built for 6 months or more.

Thanks AndrewSerk

Happy to help,

I should also mention that if you don't like to track down fedora package versions ect. Leigh was kind enough to add a fedpkg how to here. http://scientificlinuxforum.org/index.php?showtopic=153 The how to is for Howto Use Fedpkg To Build A Newer Kernel but you can use it to build any fedora package for SL if you can get the deps installed.

Thanks AndrewSerk - I'll check it out. Read a little about rpmbuild and spec files that include patches for the build process. Seems like a bit of work but may be worth it...

Hi,
Looking for a roadmap for the following question. Sorry if this has been already documented or answered...

If the current kernel being used is at this version :
http://kojipkgs.fedoraproject.org/packages/kernel/2.6.38.8/34.fc15/x86_64/

but you want to get to this version
http://kojipkgs.fedoraproject.org/packages/kernel/2.6.39/1.fc16/x86_64/

two parts are being "upgraded".
1. The FC changes from 15 to 16 and
2. the kernel changes versions.

I noticed somewhere someone else did a similar upgrade from an older kernel and FC to newer ones and that the command used to do this was:

"yum-builddep kernel-2.6.37-1.fc15.src.rpm"
(I still have to read up on the yum-builddep command but am asking this anyway-ooops )

If I do this same command to go from 2.6.38.8-34 to 2.6.39-1.fc16 will the FC15 no longer be available after the change and how will that affect the
2.6.38.8-34 kernel if I want the system to boot back into that kernel?

Another question is whether kernel patches exist for current kernels that are not rc or git but stable? I didn't see any other than the ones at kernel.org (I think there are some there but they are not Fedora or SL). Is this something that exists outside of RHEL...

Thanks for the help

Hi,
Extension to roadmap question above :-)
How do you keep from losing all the kernel settings when upgrading from one version of a kernel to another - do you have to go through the whole process of configuring the kernel again or is there a better way?
Thanks

Hello firefly,

The "yum-builddep" will install the dependencies necessary to build/use that particular package. That command will not update/upgrade the kernel just the necessary packages to to build/run the kernel.

You can have several kernels installed and choose what one to boot at the boot prompt. You can have different configurations for the different kernels and they will boot with the appropriate kernel. The number of kernels you keep installed is determined by the line( installonly_limit=3 ) in /etc/yum.conf . When you boot a kernel that is not the newest you have installed the only part of the newer kernel being used is the kernel-headers.

The kernel patches for SL, I believe, are a combo of patches from kernel.org and TUV. If you use the fedpkg way of building the kernel stop at the part after "make release" and browse the ~/fedpkg_checkout/kernel/f15 folder. You will find about 128 or so patches being used.

As far as I know, If you use custom kernel settings/patch you will have to "redo" them for every new kernel that you build/use. I don't know of a short cut for that except for the kernel modules. The dynamic kernel module builder (DKMS) will automaticly rebuild kernel modules for a new kernel if the module is registered with the DKMS package.

The kernel is the most complicated part of linux and I am still learning myself. I believe all the above to be accurate and will issue a refund if it is found not to be.

Hope this helps some,

Andrew

AndrewSerk! Thank you for your insight...

I did the fedpkg procedure and promptly forgot about it :-)....and now remember that I it, duh!


So I am trying the method for building a source kernel at http://fedoraproject.org/wiki/Building_a_custom_kernel because originally I was stuck with a card that needed patches for it to work with the kernel I was using at the time. I had to wait for the kernel to get to 2.6.39 because the v4l analog part was fixed at this version - not 100% but a lot better than before. If I had to add the patch to a previous kernel version (since the v4l patch would have been available before the 2.6.39 kernel came out) I would probably need to use the building a custom kernel method.

At this part in the doc "Copy the Source Tree and Generate a Patch"

where it talks about generating a patch I am a bit unsure of how to do that. I know the patch file would be added manually to the spec file later on but the part about adding the files to the source code to generate the patch has me a bit confused. Seems there might be two ways - 1. getting a fix through files that need to be added to the source files and then generating the patch and 2. getting a patch file and just adding it to the kernel.spec file.

It says to ->
"Make changes directly to the code in the .new source tree, or copy in a modified file. This file might come from a developer who has requested a test, from the upstream kernel sources, or from a different distribution. "

Have you seen an example of what I would need to do for this part?

Would a patch from any developer working on the same kernel version be a possibly good patch or would they mostly have to come from one source? Could the patch for the V4l analog fix been applied at this point in the custom kernel build?

Thanks

Ok, The patch was for a module so it wouldn't apply here...I think. :-)
This is the site for the patches for the card (HVR 1600 = cx18):
http://git.linuxtv.org/media_tree.git?a=commit;h=61c4f2c81c61f73549928dfd9f3e8f26aa36a8cf
Obviously I am fishing...since I have no clue - but seems likely - that git is a whole other process for updating drivers from the building a custom kernel section where you can "patch" the source code.

Hello,

I am attempting to build the linuxtv git tree. I will report back the results after building and testing.

Andrew

EDIT: I must have done something wrong as I ended up with a tainted kernel

I was just looking through the source code for kernel-3.0-0.rc5.git0.1.fc16 and it looks like the video4linux git patches are already patched in that release.
Have you tried the 3xxx kernel?

Hi AndrewSerk

With Fedora 2.6.38.8-32.fc15.x86_64, I can stream the Haupphauge 1600 card with FFMPEG feeding FFSERVER(I might need to reboot the box since audio is sometimes -i.e. 50-50 per cent of the time - not working. I am using the drivers/software from the previously mentioned location which I will put here afterwards...---here it is---->http://linuxtv.org/wiki/index.php/How_to_Obtain,_Build_and_Install_V4L-DVB_Device_Drivers

I am using mplayer on a laptop running Fedora 2.6.38.8-34.fc15.x86_64 to catch the stream and it is "fun" like this - by the way thanks for ALL your help.

I've had less luck luck with Scientific Linux but I will install the 3xxx kernel(s) to see what happens and post that...I may not get to it tonight but soon...it might be due to a learning curve on my part so I guess we will see.


Thank You AndrewSerk

Nice