hi,

> > there're ports whose cpu_startup does uvm_map_protect in order to
> > prevent COW on kernel text and NULL.
> > i don't see why they're needed.  iirc, these areas of kernel_map
> > should be reserved by uvm_km_init.  (assuming pmap_virtual_space, etc works.)
> > is there something special for these ports?  or can i just remove
> > these uvm_map_protect?
> 
> There is a scenario in the commit log:
> http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/arch/hp300/hp300/machdep.c#rev1.74
> but I'm not sure if it's still the matter.

i think that we don't have the most of the problems anymore because
the current fault handler doesn't allocate an object or an amap
on the area reserved by uvm_km_init.
although uvm_kernacc() can still be matter, it's used only for /dev/kmem,
and in that case, following uiomove() should detect an error.

YAMAMOTO Takashi