We don't need MAP_FIXED, we just want to avoid address 0 to be allocated. Though I think using MAP_FIXED is overkill, will bring much unnecessary complexity on both kernel and beignet side. I don't mind if people can provide stable MAP_FIXED patches to resolve this problem a few months or years later. At that time, kernel driver can revert the reserve page 0 patch. Before that reserve page 0 can benefit all the Beignet user without breaking anything. As I know, on CPU side, many arches with flexible address space like IA64 have reserved virtual page 0 to address this problem, I don't see why this is non sense. Thanks Zou Nanhai > -----Original Message----- > From: Chris Wilson [mailto:chris@xxxxxxxxxxxxxxxxxx] > Sent: Friday, March 06, 2015 4:39 PM > To: Zou, Nanhai > Cc: Daniel Vetter; Song, Ruiling; Vetter, Daniel; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; > Yang, Rong R; beignet@xxxxxxxxxxxxxxxxxxxxx; Weinehall, David > Subject: Re: [Beignet] Preventing zero GPU virtual address allocation > > On Fri, Mar 06, 2015 at 02:11:18AM +0000, Zou, Nanhai wrote: > > I don't understand why we need a complex solution when there is already a > simple solution with patch. > > What is the drawback of reserving page 0? > > Before we going to that complex solution, could we just reserve page zero? > > It is simple and straight forward. > > Because it is a nonsense ABI constraint. If you want the equivalent of > MAP_FIXED, we should give you MAP_FIXED. > -Chris > > -- > Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
