[rock-user] "Aborted building package glibc23." while building a rock-router distro

Hi,

when I am going to build a router distro, the build-process breaks while 
== 12:44:35 =[1]=> Building base/glibc=glibc23 [2.3.6 0] with:

!> Linux 2.0.10 or later to be installed before configuring.
!> The kernel header files are found usually in /usr/includ ..
!> /usr/include/linux; make sure these directories use file ..
!> Linux 2.0.10 or later.  This check uses <linux/version.h ..
!> make sure that file was built correctly when installing  ..
!> files.  To use kernel headers not from /usr/include/linu ..
!> configure option --with-headers.
-> $root/var/adm/logs/1-glibc23.out -> 1-glibc23.err
== 07/29/06 12:45:19 =[1]=> Aborted building package glibc23.

The 1- file says:
---[snip]---
running configure fragment for sysdeps/pthread
running configure fragment for sysdeps/unix/sysv/linux
checking for egrep... (cached) grep -E
checking installed Linux kernel header files... TOO OLD!
configure: error: GNU libc requires kernel header files from
Linux 2.0.10 or later to be installed before configuring.
The kernel header files are found usually in /usr/include/asm and
/usr/include/linux; make sure these directories use files from
Linux 2.0.10 or later.  This check uses <linux/version.h>, so
make sure that file was built correctly when installing the kernel header
files.  To use kernel headers not from /usr/include/linux, use the
configure option --with-headers.
--- BUILD ERROR ---
Creating file list and doing final adaptions ...
Processing /lib corrections ...
Verifing the .la files ...
---[snip]---

What's wrong? OK, it's missing some new headers, but ... If I'ld going to 
download the headers (where?) and unpack them, where should they be 
installed? In /usr/src? 
Regards
  Bernd