| If I read this patch correctly, you can generate a kernel for either
 | the normal MIPS1 cpu, or for this slightly different CPU but not both,
 | right?  If so, a comment to that effect needs to be inserted somewhere
 | so that people know what ENABLE_MIPS_R3900 means.

Yes.
options		MIPS1
options		ENABLE_MIPS_TX3900
 -> kernel only for R3900 core

options		MIPS1
 -> MIPS R3000 kernel. my patch has no effect.

I begin to write comment about these.
---
UCHIYAMA Yasushi
uch@nop.or.jp