> -----Original Message----- > From: Xen-devel [mailto:[email protected]] On Behalf > Of Jan Beulich > Sent: 01 August 2018 09:21 > To: Roger Pau Monne <[email protected]> > Cc: Kevin Tian <[email protected]>; Stefano Stabellini > <[email protected]>; Wei Liu <[email protected]>; George Dunlap > <[email protected]>; Andrew Cooper > <[email protected]>; Ian Jackson <[email protected]>; Tim > (Xen.org) <[email protected]>; Julien Grall <[email protected]>; xen-devel > <[email protected]> > Subject: Re: [Xen-devel] [PATCH 2/4] iommu: generalize > iommu_inclusive_mapping > > >>> On 31.07.18 at 17:33, <[email protected]> wrote: > > On Tue, Jul 31, 2018 at 08:39:22AM -0600, Jan Beulich wrote: > >> >>> On 27.07.18 at 17:31, <[email protected]> wrote: > >> > Introduce a new iommu=inclusive generic option that supersedes > >> > iommu_inclusive_mapping. This should be a non-functional change on > >> > Intel hardware, while AMD hardware will gain the same functionality of > >> > mapping almost everything below the 4GB boundary. > >> > >> So first of all - what's the motivation behind this change? So far we > >> had no need for hacks line the VT-d side one on AMD. I don't think > >> this should be widened without there being indication of a problem > >> with non-niche AMD systems. > > > > OK, I can leave the default on for Intel and off for everything else, > > but I will introduce the generic dom0-iommu= option anyway. > > Hmm, I've always been wishing we'd change to a default of off for > VT-d as well - imo we shouldn't by default assume broken firmware. > Kevin?
I suspect that a seriously large number of Xen users will find their systems fail to boot if the default is changed. I'm testing on a Dell R730 with (to my knowledge) up-to-date firmware. Not exactly a rare system and turning off inclusive mapping will cause it to wedge during boot. Paul > > As to AMD - you still don't really say why this would be needed > there. I'm not in favor of workarounds when there's nothing to > work around. IOW - if the logic isn't needed on AMD, do we need > this code movement in the first place? > > Jan > > > > _______________________________________________ > Xen-devel mailing list > [email protected] > https://lists.xenproject.org/mailman/listinfo/xen-devel _______________________________________________ Xen-devel mailing list [email protected] https://lists.xenproject.org/mailman/listinfo/xen-devel
