On Mon, Dec 26, 2016 at 04:40:16PM -0500, Mouse wrote: > > The only reason I know for mapping address zero [...] > > > Anyway mmap() without MAP_FIXED should never return NULL. > > Perhaps it's time to implement null pointers as something other than > all-bits-zero?
Wouldn't help much; the next obvious (probably only viable) candidate is all-bits-1 and then you just need a slightly larger offset from it to jump to userspace. Userspace memory shouldn't have supervisor execute permission anyway, although I suppose x86 can't represent that. -- David A. Holland dholl...@netbsd.org
