From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.71) id 1VbUrL-00068s-36 for mharc-grub-devel@gnu.org; Wed, 30 Oct 2013 08:26:51 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52856) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VbUrE-000687-Ls for grub-devel@gnu.org; Wed, 30 Oct 2013 08:26:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VbUr4-0005Gn-2v for grub-devel@gnu.org; Wed, 30 Oct 2013 08:26:44 -0400 Received: from mail-ea0-x22b.google.com ([2a00:1450:4013:c01::22b]:61868) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VbUr3-0005Gd-RP for grub-devel@gnu.org; Wed, 30 Oct 2013 08:26:34 -0400 Received: by mail-ea0-f171.google.com with SMTP id h10so614963eak.16 for ; Wed, 30 Oct 2013 05:26:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type; bh=4Rb+TEURASyYnS/+PXVr0x3IMIloNpsHadVZNLjkx8I=; b=jHE1v0n/0BO0odieG6b/qaD9EgKtBvn0c4SRUX4L7IiPghe/PeqFg3EhMMZJ7Ubjr+ 5KArkUC5xD9TKbOgS045W05vKGpplU86hUVdonEAV34nY5KQQMzzyI+TvcnKS4RgRE7A xTZbYiRanvv80gcZvpHvJ9gN6zVNHXfBfnZtTM9s27P7cchVTOJIu+bYdC3IdGweG8F5 HOK/hljrTd0uWh5ZJqPq+hVofGwrzIgdKYismst6jQbrbNKiFq0hwXArv5kuvVsNd+9U OUy0iGWuNO2NorI8/D3s0r33I71GOQBJQ+C/yp5iIXqWthg9yxVNekPIZMI6RWDzO/Qx Deyw== X-Received: by 10.14.148.136 with SMTP id v8mr4796474eej.13.1383135992977; Wed, 30 Oct 2013 05:26:32 -0700 (PDT) Received: from [192.168.1.16] (31-249.1-85.cust.bluewin.ch. [85.1.249.31]) by mx.google.com with ESMTPSA id b42sm82929695eem.9.2013.10.30.05.26.31 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 30 Oct 2013 05:26:32 -0700 (PDT) Message-ID: <5270FAF6.30600@gmail.com> Date: Wed, 30 Oct 2013 13:26:30 +0100 From: =?UTF-8?B?VmxhZGltaXIgJ8+GLWNvZGVyL3BoY29kZXInIFNlcmJpbmVua28=?= User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20131005 Icedove/17.0.9 MIME-Version: 1.0 To: Andrew Cooper Subject: Re: [Xen-devel] Grant table version References: <526EA78A.6020104@gmail.com> <526EAF78.2070408@citrix.com> In-Reply-To: <526EAF78.2070408@citrix.com> X-Enigmail-Version: 1.5.1 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="----enig2DADMBLHWRWXHKGRUEROP" X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2a00:1450:4013:c01::22b Cc: The development of GRUB 2 , "xen-devel@lists.xen.org" X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list Reply-To: The development of GNU GRUB List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 30 Oct 2013 12:26:50 -0000 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) ------enig2DADMBLHWRWXHKGRUEROP Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 28.10.2013 19:39, Andrew Cooper wrote: > On 28/10/13 18:06, Vladimir '=CF=86-coder/phcoder' Serbinenko wrote: >> Hello, all. I'm working on pvgrub2 and my problem is following: >> When you first use grant tables you commit yourself to a particular >> grant table version. GRUB has to read from disk and hence use grant >> tables. By doing so it commits anything that it loads to the same vers= ion. >> Would it be possible to have a hypercall to reset grant table version?= >> Of course, before doing such a call one would need to revoke all grant= s >> or this call would discard all current grants. >=20 > You can change back and forth with grant table versions using the > GNTTABOP_set_version hypercall, so long as you have no active grants. >=20 > It is not possible to revoke a grant, as the grant ABI guarantees that = a > successful grant stays mapped until explicitly unmapped. Otherwise, a > reset would cause unexpected pagefaults in the mapper domain. >=20 > For compatibility reasons it is not strictly required, but it is > certainly expected that a new kernel explicitly chooses a gnttab versio= n > using the hypercall. There is certainly an area for problems if pvgrub= 2 > uses grant v2, then leaves v2 active and hands off to an older kernel > who expects v1 and doesn't explicitly set the version. >=20 > From this point of view, the safe course of action is to use whichever > type of grants you want, then tear down all the front/back pairs, and > reset the version to v1 before handing off. >=20 Thank you, that's what I did now. > ~Andrew >=20 >> >> >> >> _______________________________________________ >> Xen-devel mailing list >> Xen-devel@lists.xen.org >> http://lists.xen.org/xen-devel >=20 ------enig2DADMBLHWRWXHKGRUEROP Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.15 (GNU/Linux) Comment: Using GnuPG with Icedove - http://www.enigmail.net/ iF4EAREKAAYFAlJw+vYACgkQNak7dOguQgmBIgD+M5NkwTqQ/bzU31jQ0t8/nmq1 Z4+7TWA0WTubaHOe9UwA/iM07FbUKNiK89XpO+2d+PNE9+qXwwvwYqvVZ/bLVBOM =nax/ -----END PGP SIGNATURE----- ------enig2DADMBLHWRWXHKGRUEROP--