When building 2.6.17-rc1 on sparc64 I run into this problem:
if [ -r System.map -a -x /sbin/depmod ]; then /sbin/depmod -ae -F System.map 
-b /root/RPM/BUILD/kernel-linus-2.6/temp-root -r 2.6.17-rc1.16mdksmp; fi
WARNING: /root/RPM/BUILD/kernel-linus-2.6/temp-root/lib/modules/2.6.17-rc1.16mdksmp/kernel/drivers/char/drm/drm.ko 
needs unknown symbol dma_alloc_coherent
WARNING: /root/RPM/BUILD/kernel-linus-2.6/temp-root/lib/modules/2.6.17-rc1.16mdksmp/kernel/drivers/char/drm/drm.ko 
needs unknown symbol dma_free_coherent
make: *** [_modinst_post] Error 1

I'm not subscribed to the list, just thought that I should report since it 
recently broke, so CC me if any more info is needed.
I'm also attaching my .config in case it might be of help:)
-- 
Med vennlig hilsen
Per Øyvind Karlsen