I have installed linux-2.6.21 and lzo-2.03 from source code in fedora core 7 in the same directory. Now I wanted to include header files of lzo library in the linux kernel source code. How to do that?

No idea, since your question is hard to understand. Do you have FC7? If so, did you upgrade the running system kernel, or just download kernel source into your home directory? Where do you want to put the LZO libraries?

I'm sure there's a way, but why bother?? Fedora core 7 is ancient...the latest version is 12, and 13 will be out shortly. Since as you say, this is a new install, you need to install something current, as this will make most things much easier.

I have installed lzo library in fedora core 7 linux-2.6.21 kernel and it was installed in /usr/local/include/lzo directory. Now I want to include the header files of lzo library (for example lzoconf.h, lzo1x.h, lzodefs.h) in the source code of linux (mm/vmscan.c).

I included the header files like this

#include<lzo/lzoconf.h>
#include<lzo/lzo1x.h>

When we compile the kernel it is showing some errors
CHK include/linux/version.h
CHK include/linux/utsrelease.h
CHK include/linux/compile.h
CC mm/vmscan.o
mm/vmscan.c: error: lzo/lzoconf.h: No such file or directory
mm/vmscan.c: error: lzo/lzo1x.h: No such file or directory
make[1]: ***[mm/vmscan.o] Error 1
make: *** [mm] Error 2

How I resolve this problem? What shoud I do?

You've provided some more info, but your question still doesn't make much sense. Your include files are NOT installed in /usr/local/include, except for very specific things that you install there manually. The code you're looking for is not going to be in the system-wide includes, until you put it there. Either download the RPM development headers and install them, or read the instructions that came with the .gz file.

And again: FC7 is very, VERY old. It would be a much better idea to upgrade, than to spend time developing software for such an old platform.

the software repos for the VERY VERY old fedora 7 were moved into the HISTORICAL ARCHIVES
you will need to point yum to them

BUT fedora 7 is a DEAD os
Please install the current version fedora 12 .Fedora 13 is in testing and will be out soon .

a link-- -- but i recommend you DO NOT do this--
" Repository configuration for older Fedora releases. "
http://forums.fedoraforum.org/showthread.php?t=221471

Now I have installed fedora 12 and have installed the source code also. Now I want to use the lzo library in the source code. How would I proceed?

while installing the linux-2.6.31 source code in fedora 12 I got an error

[root@pratyush linux-2.6.31]# make install
sh /home/parag/rpmbuild/SOURCES/linux-2.6.31/arch/x86/boot/install.sh 2.6.31 arch/x86/boot/bzImage \
System.map "/boot"
/sbin/new-kernel-pkg: line 277: /sbin/mkinitrd: No such file or directory
mkinitrd failed

How to resolve the problem??

linux-2.6.31 ????????

what is it you are building ??????
if a linux kernel it is old
Linux 2.6.31 kernel released on 9 September, 2009

and fedora 12 already has a newer version installed

if all you need is the CURRENT kernel's source then use yum

Hi pratyush
Here goes your solution which I got after a lot of head hunting

Good Luck!

Good luck indeed...this thread is almost a year old at this point.