From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joanna Rutkowska Subject: Re: feature suggestion: DMAR table emulation for Xen Date: Fri, 14 May 2010 12:15:54 +0200 Message-ID: <4BED22DA.9050904@invisiblethingslab.com> References: Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0795109289==" Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: "Han, Weidong" , "Cihula, Joseph" , "Kay, Allen M" , "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --===============0795109289== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig762ED09917F6F5E70E95F8CB" This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig762ED09917F6F5E70E95F8CB Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 05/14/2010 11:35 AM, Keir Fraser wrote: > On 14/05/2010 10:22, "Joanna Rutkowska" = > wrote: >=20 >> The Intel VT-d spec says that: "USB controllers and UMA integrated >> graphics devices are the only legacy device usages identified >> that depend on DMA to reserved system memory". >> >> I think we can safely ignore the legacy integrated graphics devices, >> because I would expect any VT-d enabled platform to have a modern >> graphics device and modern OS drivers that works well with VT-d (you >> even provide a dedicated DMA Remapping Unit for your integrated graphi= cs >> device, so I would expect it doesn't require any RMMR exceptions). >=20 > Yeah, actually the integrated graphics can implement all sorts of dirty= > tricks between OS driver, video BIOS, and SMM. This can rely on fixed m= emory > areas for communication -- both for host accesses and DMA, the latter > requiring RMRR setup. Maybe the RMRRs are static per-chipset, but I wou= ldn't > be too sure of it. >=20 Hmmm... Shouldn't this affect only (and potentially) the text mode display? I would expect that once Dom0 Linux takes over, it would be using its own IGD driver that is VT-d aware and is not on the mercy of the evil BIOS? And we can disable the (ugly) Xen debug output, and have Dom0 linux boot with kmodeset boot argument that would load the proper driver and switch to a graphics mode right at the beginning. j. --------------enig762ED09917F6F5E70E95F8CB Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/ iEYEARECAAYFAkvtItsACgkQORdkotfEW86YHwCbBMfQm7Xbw0gwFTofwouQ//0Q 0LgAn2KjirTqaMz+EeE9MlFrMdQG+00a =61SN -----END PGP SIGNATURE----- --------------enig762ED09917F6F5E70E95F8CB-- --===============0795109289== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel --===============0795109289==--