Re: Rumpification (was Re: CVS commit: src/usr.sbin/envstat)

[Antti Kantee <pooka%cs.hut.fi@localhost>]

On Wed Dec 15 2010 at 13:39:01 -0600, David Young wrote:
> > > I understand how avoiding prog_socket(), prog_open(), and other
> > > "descriptor-creating" routines will be difficult or impossible, however,
> > > I don't see why the rest---ioctl(), close(), dup2(), read()---cannot
> > > be handled by syscall shims that refer to a table of extant RUMP
> > > descriptors to see whether to make an ordinary syscall or a RUMP
> > > syscall.
> > 
> > Yes, that is most likely possible.  The plus side is that it reduces
> > errors when using objects and the minus side is that it hinders
> > readability.  We can certainly keep that technique under the belt in
> > case there are problems that would be trivially solved by using it.
> 
> How does it hinder readability?

It adds "magic".  Some people considering that bad.  I'm not saying it's
a dealbreaker in my opinion.

> > > Do you think that ifconfig can configure itself for RUMP/non-RUMP
> > > syscalls at run time by switching on, say, argv[0]?
> > 
> > Assuming the program has been correctly codified, yes.  But it's more work
> > for me and the 'puter.  For example, we'd have to rely on dlopen()+dlsym()
> > for the rump stubs unless we want to require rump syscall client stub
> > linkage to the one true ifconfig binary (which I think is a bad idea).
> > What's the benefit you seek?
> 
> I thought that it might be nice if we could have one in the tree and
> direct it to different backends with a command-line option: rump kernel,
> host kernel, and whatever we may think up in the future.  It's not even
> a fully-formed thought, yet.

Maybe, but can you speculate what "whatever we may think up" would be?
There's 40 years of unix saying shifts like these don't often come along.
I'm not opposed, but, as usual, I'd rather see a feature added only when
there is a use case for it.

"generalizations are generally wrong" ...

If you want to brainstorm about it, you know where to reach me.

-- 
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