Richard Weinberger wrote:

So, what exactly is broken in upstream?
make defconfig works as it always did.

Auto-detection of SUBARCH, which can be done with a simple call to
uname -m (the 90% case). The second patch I submitted prevented
spawning xterms unnecessarily, which we discussed was a good move.

make defconfig ARCH=um SUBARCH=x86 (or SUBARCH=i386) will create a defconfig for 32bit.
make defconfig ARCH=um SUBARCH=x86_64 one for 64bit.

Yes, that's how I prepared the patch in the first place.