buildroot to build toolchain on Linux

Hi hippo,there is a pb:

[root@nios download]# cd ~/linux-2.6.16.1

[root@nios linux-2.6.16.1]# make ARCH=nios2nommu CROSS_COMPILE=nios2-linux-uclibc- hwselect SYSPTF=std_1c20.ptf

Makefile:524: /root/linux-2.6.16.1/arch/nios2nommu/Makefile: 没有那个文件或目录

make: *** 没有规则可以创建目标“/root/linux-2.6.16.1/arch/nios2nommu/Makefile”。 停止。

[root@nios linux-2.6.x]# ls /root/linux-2.6.16.1/arch/

alpha cris i386 m68k parisc s390 sparc v850

arm frv ia64 m68knommu powerpc sh sparc64 x86_64

arm26 h8300 m32r mips ppc sh64 um xtensa

there is no "nios2nommu" in that dir