hi,

> > i'd like to change M_READONLY like the following.
> > there's no point to protect external storage if it isn't shared.
> > eg. receive buffers for jumbo frame.
> 
> How would this work e.g. with a buf loaned to an mbuf ... I don't think 
> you want to scribble over that buf, right?

i think that checking M_EXT_ROMAP is enough for loaned buffers
because they're read-only mapped in kernel.
if it isn't enough (although there's currently no case i can think of),
we can introduce a new flag, say, M_EXT_READONLY.

YAMAMOTO Takashi