svn commit: r284146 - in head/tools/bus_space: . C Python

[Bruce Simpson]

Marcel,

(Cc: Will as he's expressed interest in this)

No problem... still tied up here...

On Mon, 8 Jun 2015, at 06:10, Marcel Moolenaar wrote:
> > On Jun 7, 2015, at 9:52 PM, Bruce Simpson <bms at fastmail.net> wrote:
> > Nice! Is there a man page or documentation for this anywhere?
> 
> Not yet. I want to flesh it out further before documenting.
> I’m not sure the API is stable enough yet. I’m still figure
> things out as I go.

> > Also: is it feasible to extend to build/attach to a VirtIO function?
> > (May be PCI, not MMIO).
> 
> I think so. If there’s an easy environment for me to play
> with, I can take a look. I think qemu would do right?

If you load a FreeBSD VM into KVM, and turn on host-guest sharing,
you'll see a VirtIO function for Plan 9's v9fs exposed on the PCI bus.
This speaks a Linux-specific variant of the 9P protocol, 9P2000.L.

FreeBSD currently does not understand how to talk to it, nor do our
existing 9p ports. BHyve doesn't support host-guest sharing (yet).

Note: I neither claim nor argue that this is the most efficient
host-guest solution -- there are anecdotal reports that the claims IBM
have made in published papers cannot be verified in production -- but it
makes sense to re-use (and perhaps improve upon) what IBM have done
here, for the sake of interop more than anything else.

There is a FUSE-based implementation in Python, py9p, which might serve
as the basis for a prototype. NetBSD have a newer alternative but it
looks like more work to make it talk to the VirtIO function.

-- 
BMS (sent via webmail)