Right now sparc64 has achieved the impressive feat of not compiling
with allnoconfig (in fact the very first source file, init/main.c,
won't build).

This is because various structures and so on use types that are only
defined if CONFIG_COMPAT is on, but allnoconfig sets
CONFIG_SPARC32_COMPAT and therefore CONFIG_COMPAT to n.  I'm including
two possible solutions: one trivial one that forces
CONFIG_SPARC32_COMPAT to y, and one that actually tries to make the
CONFIG_COMPAT=n case work.

I don't actually have any hardware to try this on since I only
discovered the problem testing my driver for portability by
cross-compiling (I use allnoconfig to make my build as quick as
possible).  In fact I'm not sure if anyone has a full 64-bit userspace
for sparc64.  Therefore the first patch is probably the best fix, but
I leave it up to the experts.

I'm including the simple fix inline and attaching the big fix.

Thanks,
  Roland

Index: linux-2.6.7-sparc64/arch/sparc64/Kconfig
===================================================================
--- linux-2.6.7-sparc64.orig/arch/sparc64/Kconfig	2004-07-08 20:07:28.000000000 -0700
+++ linux-2.6.7-sparc64/arch/sparc64/Kconfig	2004-07-09 20:43:11.000000000 -0700
@@ -348,7 +348,8 @@
 	  module will be called openpromfs.  If unsure, choose M.
 
 config SPARC32_COMPAT
-	bool "Kernel support for Linux/Sparc 32bit binary compatibility"
+	bool "Kernel support for Linux/Sparc 32bit binary compatibility" if BROKEN
+	default y
 	help
 	  This allows you to run 32-bit binaries on your Ultra.
 	  Everybody wants this; say Y.