> I've finished the initial implementation of direct I/O,
> there's an updated diff in:
> 
> ftp://ftp.netbsd.org/pub/NetBSD/misc/chs/dio/diff.directio.3

- you need to check values of uvm_km_alloc or specify UVM_KMF_WAITVA.

- what prevents the vnode from getting VMAPPED,
  while you are sleeping somewhere in genfs_do_directio?

YAMAMOTO Takashi