Can anybody come up with some theories as to why ARM kernels might be 
tripping the assertion in "umap->refcount != 0" in ubc_map.c when 
bootstrapping gcc?  Although it's not predictable as to when it will fail, 
it does seem to happen pretty much every time, and it's been doing this on 
all kernels since late October last year.

Here's an example (copied down by hand)

	panic: assertion failure: umap->refcount != 0

	from: ubc_fault
		uvm_fault
		data_abort_handler
		uio_move
		ffs_write
		VOP_WRITE
		vn_write
		dofile_write
		sys_write
		syscall_plain
		swi_handler


R.