From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59799) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZXKAq-0004XJ-CH for qemu-devel@nongnu.org; Wed, 02 Sep 2015 22:22:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZXKAm-0004U8-F0 for qemu-devel@nongnu.org; Wed, 02 Sep 2015 22:22:48 -0400 Date: Thu, 3 Sep 2015 12:17:48 +1000 From: David Gibson Message-ID: <20150903021748.GG6537@voom.redhat.com> References: <1441046762-5788-1-git-send-email-thuth@redhat.com> <1441046762-5788-3-git-send-email-thuth@redhat.com> <20150902053412.GE13778@grmbl.mre> <20150902074801.GA6537@voom.redhat.com> <1441243284.7931.1.camel@ellerman.id.au> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="vSsTm1kUtxIHoa7M" Content-Disposition: inline In-Reply-To: <1441243284.7931.1.camel@ellerman.id.au> Subject: Re: [Qemu-devel] [PATCH v2 2/2] ppc/spapr_hcall: Implement H_RANDOM hypercall in QEMU List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Michael Ellerman Cc: Thomas Huth , qemu-devel@nongnu.org, armbru@redhat.com, agraf@suse.de, qemu-ppc@nongnu.org, Amit Shah --vSsTm1kUtxIHoa7M Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Sep 03, 2015 at 11:21:24AM +1000, Michael Ellerman wrote: > On Wed, 2015-09-02 at 17:48 +1000, David Gibson wrote: > > On Wed, Sep 02, 2015 at 11:04:12AM +0530, Amit Shah wrote: > > > On (Mon) 31 Aug 2015 [20:46:02], Thomas Huth wrote: > > > > The PAPR interface provides a hypercall to pass high-quality > > > > hardware generated random numbers to guests. So let's provide > > > > this call in QEMU, too, so that guests that do not support > > > > virtio-rnd yet can get good random numbers, too. > > >=20 > > > virtio-rng, not rnd. > > >=20 > > > Can you elaborate what you mean by 'guests that do not support > > > virtio-rng yet'? The Linux kernel has had the virtio-rng driver since > > > 2.6.26, so I'm assuming that's not the thing you're alluding to. > > >=20 > > > Not saying this hypercall isn't a good idea, just asking why. I think > > > there's are valid reasons like the driver fails to load, or the driver > > > is compiled out, or simply is loaded too late in the boot cycle. > >=20 > > Yeah, I think we'd be talking about guests that just don't have it > > configured, although I suppose it's possible someone out there is > > using something earlier than 2.6.26 as well. Note that H_RANDOM has > > been supported under PowerVM for a long time, and PowerVM doesn't have > > any virtio support. So it is plausible that there are guests out > > there with with H_RANDOM support but no virtio-rng support, although I > > don't know of any examples specifically. RHEL6 had virtio support, > > including virtio-rng more or less by accident (since it was only > > supported under PowerVM). SLES may not have made the same fortunate > > error - I don't have a system handy to check. >=20 > There also could be folks who want to run non-Linux operating systems, wh= ich > don't have a virtio-rng driver, crazy I know :) Well, yes. Although I don't have any concrete examples of those, either.. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --vSsTm1kUtxIHoa7M Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJV563MAAoJEGw4ysog2bOS7GMP/2G2+c1wwS0TJa74gO4yhhAn osmOzfwChR/4mMl9utoMdxjkDcLNHCGdswPOvDIywSO2x5xLlt+n+LsZaTolO7hC rxYvBLQe0/qfKy6fJM2vWbxhao/Y2lLkqATGaU+JmhaYqp7Vv1d3/87cjRkm5SFl 4hjoGj/Dnof0QzYM8rbj+J3DaPDfDSn0C+mJBnk1pZvzzyHX71hgFl8u58s3y+0C TgA4rRkbzbogHFkywL53fLwLGGaEtU4t3OBRDo3kwusrno8j60uVFnNsjQYbohBP +dRuO9UH4mFRKhHSfTsXcGooMmhr5I3Dw+Pt1MlUaAzjtL5HqyypdLV8728hMNae 6oXYn/xvtK7sge6eKXsmy5XVxKCXmiymu0kwsxQ9ma47jD3hK/nqEDrXe+Qj9EHS 5sp2z4cfZ9drFrr7mS73GWpkI6E51PRa4Eg9fUXtyrODYOF+2O2OGm2h4X5b7Srx W7pCZgHfc4+4Jx/mCN+UIE0N4HefEUWSlSeOPY9yF45LrdZog6hhBuZdQAWBZS/o VqybtZ4O4MSskB8YbdBZixUnsVmry0FmYwqF/i6+nC8ikY0rMH7q0KVqaQk6nqjs 6/tFUYoXwrVkRvD1ogop9cfIhZMO3BE0uqJwcPdYNOvrYebiveDzLbCqTDitBb1P IXcXF8Tlwz+dgqKSYTsv =k73E -----END PGP SIGNATURE----- --vSsTm1kUtxIHoa7M--