From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60945) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z4jb9-00038z-N1 for qemu-devel@nongnu.org; Tue, 16 Jun 2015 01:39:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z4jb8-00024O-Ha for qemu-devel@nongnu.org; Tue, 16 Jun 2015 01:39:47 -0400 Date: Tue, 16 Jun 2015 15:40:05 +1000 From: David Gibson Message-ID: <20150616054005.GP13352@voom.redhat.com> References: <1433478358-993-1-git-send-email-bharata@linux.vnet.ibm.com> <1433478358-993-6-git-send-email-bharata@linux.vnet.ibm.com> <20150615065908.GJ13352@voom.redhat.com> <20150615101509.57063182@thh440s> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="PT0wT86ZVVq2zanE" Content-Disposition: inline In-Reply-To: <20150615101509.57063182@thh440s> Subject: Re: [Qemu-devel] [PATCH v4 5/8] spapr: Consolidate cpu init code into a routine List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Thomas Huth Cc: qemu-devel@nongnu.org, mdroth@linux.vnet.ibm.com, agraf@suse.de, aik@ozlabs.ru, qemu-ppc@nongnu.org, tyreld@linux.vnet.ibm.com, Bharata B Rao , nfont@linux.vnet.ibm.com --PT0wT86ZVVq2zanE Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jun 15, 2015 at 10:15:09AM +0200, Thomas Huth wrote: > On Mon, 15 Jun 2015 16:59:08 +1000 > David Gibson wrote: >=20 > > On Fri, Jun 05, 2015 at 09:55:55AM +0530, Bharata B Rao wrote: > > > Factor out bits of sPAPR specific CPU initialization code into > > > a separate routine so that it can be called from CPU hotplug > > > path too. > > >=20 > > > While at this, use MSR_EP define instead of using 6 directly. > >=20 > > Don't do this please. MSR[EP] is an obsolete flag from 601. The > > MSR[IP] flag that we're controlling here just happened to re-use the > > same bit position, so using the existing MSR_EP define is misleading. >=20 > Actually, I had the same discussion with Bharata already some weeks ago: >=20 > http://lists.gnu.org/archive/html/qemu-ppc/2015-05/msg00133.html >=20 > > A symbolic name is good, but you should create a new one for MSR[IP] > > instead. >=20 > ... and I had to realize that IP =3D EP. IP likely stands for "interrupt > prefix" (I guess), and EP simply means "exception prefix", so just two > words for the same meaning. It's just the "on 601" comment in QEMU that > is completely misleading. So IMHO it should be fine to keep the > "MSR_EP" here (and maybe update the comment in cpu.h with a separate > patch?). I don't entirely agree. Yes EP and IP have related functions - it's pretty common in ppc history that when an MSR bit is re-used it's for something similar (for example IS/IR). But MSR[IP] is still a different name from MSR[EP], and I don't know if the semantics are identical, though I'm sure they're similar. --=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 --PT0wT86ZVVq2zanE Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJVf7a1AAoJEGw4ysog2bOSq2gQAJBS7VJ4SqIEHhslL5v1YJne 169yzNPL/JRfrOKwcumXbYPFv5NmIZothC2/Hu67bMsCQI/jXApyRRCv/Z0Ba5se n2rPXdqXu7Ed/ne7UBbq3t7LWN4IUPIl02pEBZxtHtKOyBS+aBx9XkItgYA8oPv0 s92VP3PwlQdgCoxiiLVXJzTV1SBp/AMrKeMdxD0/7YF3usFLb1AwBANs6b/ZIU2+ nfiWYngw6eJGBIWGPgTqg6uNFCPr6CyjlN8usNAYOopPFnohEadcpqzwPGa5SFmT 8YXvNEZafWYKsdv1DBpQNvP+j8CLh5ECbzCPizAM1HZ7GT8S/AeVrv7EIcpQJDvd LDA0Ff36qR7AlcFBY7/Q72oXP/JRAtAPHtO5wprpJLHXA0DyCSciFvJxPSvlX/7T +5qGKrQwsL2LWMg25JkmIs+UL6r39gjbFS5chVjmKgpD5W0gg5yxrDR6uWUfVBzR 84lM88r76rFDboaiL9ZXJrw4UUPPURfQ3lx/1kjF573J9GS/D7EwmkL/LeHxJUJd 1TXFx2WCyMIuvo9lOpRh/ZZk0qFhwrQerTIfvhDMTf56OMGOq9FLYqFA4tItsnO5 zSuvwD5d/ONE0Uv/+2U/HWSwyupvHeBYH1MmLV3WwDSSpUyJp5kUboO2s9MBRG38 DKCD88y54vfR3MJuHlhx =ArmL -----END PGP SIGNATURE----- --PT0wT86ZVVq2zanE--