Subject: Re: ok to bump vnd to 32 in XEN0 config?
To: Juan RP <juan@xtrarom.org>
From: Quentin Garnier <cube@cubidou.net>
List: port-xen
Date: 01/31/2006 11:18:00
--Do9hQ/bfCb4zBpLo
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable
On Tue, Jan 31, 2006 at 03:06:09AM +0100, Quentin Garnier wrote:
> On Tue, Jan 31, 2006 at 11:24:01AM +1100, Daniel Carosone wrote:
> > On Tue, Jan 31, 2006 at 01:16:13AM +0100, Juan RP wrote:
> > > On Tue, 31 Jan 2006 09:26:38 +1100
> > > Daniel Carosone <dan@geek.com.au> wrote:
> > >=20
> > > > How hard would it be to make these cloning-type devices, created on
> > > > demand? (the devices, not the /dev nodes, that's another bikeshed =
:)
> > >=20
> > > Do you mean a device clonning as was implemented for bpf(4) or tap(4)
> > > or are you talking about something else?
> >=20
> > Yes, just like that, though perhaps a closer implementation analogue
> > would be the way that sd(4) instances or wedges can come and go
> > dynamically, just because its disks and not network devices.
>=20
> However the kernel creates the instances, you still need, for vnd, a
> userland entrypoint to send the 'create' command. That's what cloning
> devices are for.
>=20
> It shouldn't be too hard to do; I might have time to look at it this
> week, but I wouldn't mind if someone else had a try. tap(4) should have
> all the necessary logic. The only thing to take care of is providing an
> API so that vnconfig can tell the user which device it has created, and
> that's exactly how the cloning device of tap works. It is different from
> bpf(4) in that respect, because bpf is "open once for each use", i.e. the
> created device doesn't last longer that the time it is opened.
So, I've thought about that a bit more. I don't think we need a cloning
device here. We just need vnd(4) to create vnd<N> when the user does
'vnconfig -c vnd<N>'.
--=20
Quentin Garnier - cube@cubidou.net - cube@NetBSD.org
"When I find the controls, I'll go where I like, I'll know where I want
to be, but maybe for now I'll stay right here on a silent sea."
KT Tunstall, Silent Sea, Eye to the Telescope, 2004.
--Do9hQ/bfCb4zBpLo
Content-Type: application/pgp-signature
Content-Disposition: inline
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.6 (NetBSD)
iQEVAwUBQ985WNgoQloHrPnoAQJLTwgAjwTmQx+x9z0dSZthBRA3iJeOrVlOKnO5
6fNegxxlcx1AyaGJlLNTzJVar1157g8DxmOEegl2cJISDM5SnE1t+k+Wy3Np3amx
o5DTXn2KTvj/tUA8y6f2IPJLcdfjkAhqnuNhiHVGYHr3NM7Oahfh0pqCbn5xBDOS
E5fZrvhV4JvmzyAAh5LWviaC28wtg9Ed5lbIphmqq3qisq45fM2t+Q1sgxFMerN3
A8e17fhrK38deGPXIkS7FxAZEODsIQN8AQ7T7NFsnCBTAYV+fGCAHU6AkZO/q2Il
mjWPK+EXbhlZiZMXwbvWEygLNhCXfIfLkZXd3xJ5htCBE2EExaHvww==
=FogZ
-----END PGP SIGNATURE-----
--Do9hQ/bfCb4zBpLo--