RT Kernel compile and install help needed.

RT Kernel compile and install help needed.

[Chanchal Paul]

Hi,

I am fairly new to kernel compilation and installation process, still i
managed to learn from Kernelnewbies and RT-wiki and managed to patch
3.12.14 vanilla kernel with rt patch 3.14.12. Then I followed the steps and
installed rt-kernel in my lubuntu vm. While doing "make menuconfig" i
selected preemtion model as BASIC-RT from processor type and features
option. It worked.

Now my confusion arises when i see my uname -a string as "Linux
paul-lubuntu 3.14.12-rt9 #2 SMP PREEMPT Tue Oct 28 13:30:27 UTC 2014 x86_64
x86_64 x86_64 GNU/Linux" which indicated that i have a preemptive kernel
installed. but the c program from "
https://rt.wiki.kernel.org/index.php/RT_PREEMPT_HOWTO" for "Runtime
detection of an RT-PREEMPT Kernel" only prints "this is a vanilla kernel".
So, my question is am I running a vanilla kernel or a real-time kernel? If
I am not then what are the steps to properly install a real-time kernel?

Thanking you for giving attention to my mail.
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RT Kernel compile and install help needed.

[Chanchal Paul]

I am fairly new to kernel compilation and installation process, still
i managed to learn from Kernelnewbies and RT-wiki and managed to patch
3.12.14 vanilla kernel with rt patch 3.14.12. Then I followed the
steps and installed rt-kernel in my lubuntu vm. While doing make
menuconfig, i selected preemtion model as BASIC-RT from processor type
and features option. It worked.

Now my confusion arises when i see my uname -a string as [Linux
paul-lubuntu 3.14.12-rt9 #2 SMP PREEMPT Tue Oct 28 13:30:27 UTC 2014
x86_64 x86_64 x86_64 GNU/Linux] which indicated that i have a
preemptive kernel installed. but the c program from RT_PREEMPT_HOWTO
section of RTwiki website for Runtime detection of an RT-PREEMPT
Kernel only prints [this is a vanilla kernel]. So, my question is am I
running a vanilla kernel or a real-time kernel? If I am not then what
are the steps to properly install a real-time kernel?

Thanking you for giving attention to my mail.

Re: RT Kernel compile and install help needed.

[Ralf Mardorf]

On Tue, 4 Nov 2014 17:09:13 +0530
Chanchal Paul <paulchanchal.ece@gmail.com> wrote:

> I am fairly new to kernel compilation and installation process, still
> i managed to learn from Kernelnewbies and RT-wiki and managed to patch
> 3.12.14 vanilla kernel with rt patch 3.14.12. Then I followed the
> steps and installed rt-kernel in my lubuntu vm. While doing make
> menuconfig, i selected preemtion model as BASIC-RT from processor type
> and features option. It worked.
> 
> Now my confusion arises when i see my uname -a string as [Linux
> paul-lubuntu 3.14.12-rt9 #2 SMP PREEMPT Tue Oct 28 13:30:27 UTC 2014
> x86_64 x86_64 x86_64 GNU/Linux] which indicated that i have a
> preemptive kernel installed. but the c program from RT_PREEMPT_HOWTO
> section of RTwiki website for Runtime detection of an RT-PREEMPT
> Kernel only prints [this is a vanilla kernel]. So, my question is am I
> running a vanilla kernel or a real-time kernel? If I am not then what
> are the steps to properly install a real-time kernel?
> 
> Thanking you for giving attention to my mail.

Assume you should use Debian/Ubuntu or Arch Linux I can help you to
build a kernel-rt package. As long as RT isn't mentioned in the uname -a
string, you don't run a kernel-rt. Did you copy the original config of
your installed distros's kernel, run make oldconfig and cared about
questions regarding RT?

Please consider to ask such a question at
http://lists.linuxaudio.org/listinfo/linux-audio-user instead of this
list.

Re: RT Kernel compile and install help needed.

[Ralf Mardorf]

> lubuntu

Oops ;).

Please subscribe to
https://lists.ubuntu.com/mailman/listinfo/ubuntu-studio-users

I'm short in time now, but within the next days I can explain how to
compile the kernel-rt and building a package for *buntu.

RT Kernel compile and install help needed.

[Valdis.Kletnieks at vt.edu]

On Tue, 04 Nov 2014 13:07:47 +0530, Chanchal Paul said:

> I am fairly new to kernel compilation and installation process, still i
> managed to learn from Kernelnewbies and RT-wiki and managed to patch
> 3.12.14 vanilla kernel with rt patch 3.14.12.

You *really* want to get the correct patch on the kernel release. Mixing
and matching a 3.12 kernel and a 3.14 patch will almost certainly lead to
weird results.

> Now my confusion arises when i see my uname -a string as "Linux
> paul-lubuntu 3.14.12-rt9 #2 SMP PREEMPT Tue Oct 28 13:30:27 UTC 2014 x86_64
> x86_64 x86_64 GNU/Linux" which indicated that i have a preemptive kernel
> installed. but the c program from "
> https://rt.wiki.kernel.org/index.php/RT_PREEMPT_HOWTO" for "Runtime
> detection of an RT-PREEMPT Kernel" only prints "this is a vanilla kernel".
> So, my question is am I running a vanilla kernel or a real-time kernel? If
> I am not then what are the steps to properly install a real-time kernel?

After applying the patch, you need to run 'make menuconfig' or similar
and actually enable the hard realtime support.

Also, be aware that most of the -rt patch has over the years been upstreamed,
so for the vast majority of uses, applying the patch isn't really worth
it - 95% of the people using that patch don't get any measurable benefit.

(Yes, most of the people using it *claim* they get "better latency response"
from their desktop.  And most of them are having total placebo effect. They
think they should get better response, so they think they get it.  Nobody's
actually done a blind study, where grub randomly boots one kernel or another
and the user doesn't know which, and measured any difference that way....)
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