redhat linux 7.3 - how to reconfigure kernel

[Vimala L]

Hello there.

I need to increase shmmax limit in my system. My system has redhat linux 7.3 installed.

I'm referring to manuals and I find that I have to run "make config" or "make xconfig" under /usr/src/linux/.

The /usr/src/linux/ in my m/c is a link to /usr/src/redhat/. Under that there are some directories (BUILD, and some more) but not any files under those directories. So, obviously doing "make config" under /usr/src/linux/ is failing.

Is there any command in linux similar to HP-UX's "sam"?

Please help with inputs on how to configure kernel parameters and how to remake kernel.

Thank you,
Vimala.
02-Sep-2002

[U.SivaKumar_2 · Accepted solution]

Hi,
you need not compile the kernel for that.
As i have answered for your earlier post.
do this As root:
# echo `expr 1024 \* 1024 \* 1024` > /proc/sys/kernel/shmmax
It is recommended to increase the shmmax setting permanently for Oracle. So if you want to increase the maximum shared memory size permanently, add the following line to the /etc/sysctl.conf file:
kernel.shmmax=1073741824


regards,
U.SivaKumar

[Dirk Wiedemann]

Hello Vimala,

to increase shmmax see the posting from U.SivaKumar.
But if you still want to reconfigure and build a new kernel (on a modern linux in most cases this is not necessary): first you must install the source-pakages for your actually used kernel. You found it on your distribution cd's. You also need a C-compiler and all related stuff (developer pakages).
In make xconfig you than found a lot of kernel parameters, be careful when changing - and first make a copy of your actual kernel to boot from if the new kernel fails!

regards
Dirk

[Kodjo Agbenu]

Hello,

I agree with all what was said before.

Just a warning : on Linux, recompiling the kernel actually means ... recompiling ! Not just relinking as in Hp-Ux.
Don't ever try doing this operation on a production system if you are not expert of it (and even if you are) because it is a risky operation.

Good luck.

Kodjo

[Vimala L]

Thankyou Sivakumar. It worked. [I'm sorry. I posted this message before reading your earlier reply.]

Dirk,
I have the whole set of RedHat Linux 7.3 CDs. Is there anyway I can easily identify the right source packages that are required to be installed to rebuild the kernel? Each CD has hundereds of RPMs and I haven't yet come across a document that explains about each RPM.

I'm setting up a new system and in this process I wish to rebuild the kernel too. It is alright if I lose data by rebuilding the kernel.

Please advise about the source packages I'd need.


Thanks Kodjo, for your caution. I shall keep it in mind when I handle sensitive environment.

Thank you,
Vimala.
04-Sep-2002

[Dirk Wiedemann]

Hallo Vimala,
for information about creating a new kernel under redhat have a look at http://www.redhat.com/docs/manuals/linux/RHL-7.3-Manual/custom-guide/ch-custom-kernel.html
But differing from this document I found the pakage kernel-source-2.4.18-3.i386.rpm not on CD #1 but #2.
I can't give you more detailed explanations, because I use SuSE and only have the redhat 7.3 CD's (but not installed).
Dirk