> >> I think extent is still needed at
> >> least, because I don't think the Solaris vmem system really addresses
> >> this need (at least Solaris 9 didn't -- they have separate code built on
> >> top of kmem_alloc for that.)
> >>     
> >
> > what's the particular feature of extent, which can't be done with vmem,
> > in your mind?
> > "fragment" case of extent_free?
> >   
> 
> The ability to match particular alignment constraints, for one. This can
> be implemented on top of kmem_alloc of course, but may be less efficient
> in such a case.

solaris vmem_xalloc has constraint arguments, including alignment,
doesn't it?  (no idea about its efficiency or implementation, tho.)

> > although i don't know solaris internals much, i guess it doesn't distinguish
> > intrsafe/nointr allocations as we does.  right?
> >   
> 
> It does. Look at KM_NOSLEEP in the flags argument. KM_SLEEP allocations
> are not interrupt safe, KM_NOSLEEP allocations never sleep, and hence
> are interrupt safe (but may fail).

even if you never sleep, our kernel_map is not interrupt safe.

YAMAMOTO Takashi