From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48948) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a3Zxy-00074O-MF for qemu-devel@nongnu.org; Mon, 30 Nov 2015 20:42:51 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a3Zxv-0001AU-TQ for qemu-devel@nongnu.org; Mon, 30 Nov 2015 20:42:50 -0500 Date: Tue, 1 Dec 2015 12:43:21 +1100 From: David Gibson Message-ID: <20151201014321.GI31343@voom.redhat.com> References: <1448024079-20808-1-git-send-email-bharata@linux.vnet.ibm.com> <20151123115433.GK5034@andariel.pipo.sk> <56530EEE.7050206@de.ibm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="y96v7rNg6HAoELs5" Content-Disposition: inline In-Reply-To: <56530EEE.7050206@de.ibm.com> Subject: Re: [Qemu-devel] [PATCH v5 00/10] sPAPR CPU hotplug List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Christian Borntraeger Cc: qemu-devel@nongnu.org, Peter Krempa , aik@ozlabs.ru, agraf@suse.de, mdroth@linux.vnet.ibm.com, pbonzini@redhat.com, qemu-ppc@nongnu.org, tyreld@linux.vnet.ibm.com, Bharata B Rao , imammedo@redhat.com, nfont@linux.vnet.ibm.com, afaerber@suse.de --y96v7rNg6HAoELs5 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Nov 23, 2015 at 02:04:46PM +0100, Christian Borntraeger wrote: > On 11/23/2015 12:54 PM, Peter Krempa wrote: > > On Fri, Nov 20, 2015 at 18:24:29 +0530, Bharata B Rao wrote: > >> This patchset adds CPU hotplug support for sPAPR PowerPC guests using > >> device_add and device_del commands > >> > >> (qemu) device_add POWER8-powerpc64-cpu,id=3Dcpu0 > >=20 > > Is there a reason why this uses 'device_add' rather than the 'cpu_add' > > command? Libvirt uses two separate approaches already. Due to legacy > > reasons we support the HMP 'cpu_set' command, and lately we added > > support for QMP 'cpu-add'. Using device_add here will introduce a > > different approach and will require yet another compatibility layer in > > libvirt to support this. >=20 > s390 and powerpc both started with cpu_add patches. Andreas Faerber > suggested then to only implement device_add. This was apparently discussed > at the last KVM forum. This may not be the only reason, but one problem with cpu_add is that the interface is strictly per-vcpu, i.e. per-thread. That doesn't work for Power guests, because the PAPR interface used to communicate to the guest can only work at a core granularity. --=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 --y96v7rNg6HAoELs5 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJWXPs5AAoJEGw4ysog2bOSUQwP/R7dC1fjMpqQlTq4n51wAKbr TMDYqNiH9IqmOICIcDmmQBCx7pSGgdOcaq/3RGIlZduwoiLwJpcWAp1AEtrXWD/u ZRvCmrM/ZFUgtk0rUMQjsblFGAvl9/B1abs7vIUHFA81LUHtEWx+tx8ShBndzwJk hdNP01Q7U+w1NVUW0bbXHqbHPUPaMUxVkgMsEKbPiLUtSk/u7FDGwOpHEd+hfE1Q WfOD2B/9akyHMJ4T7cUYyjOuRHP0uK2yzwnwqY3KDu9zm2Zr/qVcl2jjQVdz2uFd zOe6itZ5d+GchDiS9D3HwJAwbRoeLBP7NRLrSDwdmnXwir9W8MHtV3+sJNwWZR4O VNkC/lLmSdlNyigrHgI7CenklHpslncyPX1GgkItGUoQIA+1u8DOE5N6A0s4ilUh 266TE7AkBybbUy7acBvRautYi1G9ZksTEeZoTiH3WkxdfrX/hTEkOhz560YVVpIA tI7Zda/j+4X2WcL54qx2MRgaXN5aqpVPbAftmxJya+G/OCFYnl5RrTcP7iWB+O1M Kw3PPNWIc8T5pIAKBl8GVs8/OtvWawfq6MDGLxrCZ3de4ipO63cWbLtlLR95m8Ep u38s85K9P+o/r7VVbkt4NSk4/BeiPyrZrTcfkrroZj2+3gk9jiuJ4Bk2Oi9iNSlk VeNeE2pChWOlthVG6z5k =ey2b -----END PGP SIGNATURE----- --y96v7rNg6HAoELs5--