Re: [9fans] mmap

[Bakul Shah <bakul+plan9@bitblocks.com>]

On Thu, 31 Jul 2008 22:39:43 BST Charles Forsyth <forsyth@terzarima.net>  wrote:
> > Does anyone have pointers to *nice* interfaces for doing this?  I don't
> > care which OS, but I'd like to not have the implementation I'm
> > requesting suck because I missed some gotchas that someone else already hit.
>
> paul lalonde's request is a good one, but i think a useful qualification is
> that it should also be shown in practice to have a reasonable implementation
> on several agreeably different architectures.  one of the reasons mmap is
> bad is that like job control it whacked some vague ideas into an existing
> system without reference to its existing conventions, then vaguely extended
> it in a vague way from time to time, vaguely different from platform to
> platform, and with vague documentation.  ``could they be any more vague?''

I vaguely remember seeing a comment on Karels and McKusick's
original mmap proposal (about 20 years ago).  I think it was
by dmr.  Something to the effect that if such a facility is
desired it should be made as integral to the OS as an inode
is to Unix (and not bolted on the side). Makes for an
interesting thought experiment as potentially all sorts of
simplifications are possible.