From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52287) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fDuDv-0000Bq-Dn for qemu-devel@nongnu.org; Wed, 02 May 2018 12:03:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fDuDu-0004SG-JT for qemu-devel@nongnu.org; Wed, 02 May 2018 12:03:19 -0400 From: Paul Durrant Date: Wed, 2 May 2018 16:03:09 +0000 Message-ID: <683868567d3f4ed5a0f5eae7c0d2d4a3@AMSPEX02CL03.citrite.net> References: <1525089699-13411-1-git-send-email-paul.durrant@citrix.com> <20180502155816.GD14376@perard> In-Reply-To: <20180502155816.GD14376@perard> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH 0/4] block/xen_disk: legacy code removal and cleanup List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Perard Cc: "xen-devel@lists.xenproject.org" , "qemu-block@nongnu.org" , "qemu-devel@nongnu.org" , Stefano Stabellini , Kevin Wolf , Max Reitz > -----Original Message----- > From: Anthony PERARD [mailto:anthony.perard@citrix.com] > Sent: 02 May 2018 16:58 > To: Paul Durrant > Cc: xen-devel@lists.xenproject.org; qemu-block@nongnu.org; qemu- > devel@nongnu.org; Stefano Stabellini ; Kevin Wolf > ; Max Reitz > Subject: Re: [PATCH 0/4] block/xen_disk: legacy code removal and cleanup >=20 > On Mon, Apr 30, 2018 at 01:01:35PM +0100, Paul Durrant wrote: > > The grant copy operation was added to libxengnttab in Xen 4.8.0 (releas= ed > > nearly 18 months ago) but the xen_disk PV backend QEMU is still carryin= g > > a significant amount of code purely to remain compatible with older > > versions of Xen. > > > > As can be inferred from the diff stats below, removing this support for > > older versions of Xen from QEMU reduces the size of the xen_disk source > by > > more than 350 lines (~25%). The majority of this is done in patches #1 > > and #2. Further simplifications are made in patch #3 and then some > cosmetic > > work is done in patch #4. >=20 > FIY, I don't like this patch series. We've been checking that QEMU > builds against older version. I've check that it builds against 4.5 and > newer. >=20 Ok, I can grant copy emulation in QEMU then should it not exist for the par= ticular Xen/OS combo. > Also the fact that FreeBSD doesn't have support for grant copy probably > mean that it is too soon to remove the compatibility code from qemu. >=20 On another thread I'd already agreed to emulate grant copy in libxengnttab = for those OS where it is not supported, but if you prefer it to be in QEMU = I'll put it there. Paul > Regards, >=20 > -- > Anthony PERARD