From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Martin Subject: Re: Consuming PCI device in PV kernel Date: Fri, 25 Jul 2014 15:20:48 +0100 Message-ID: <13170235.20140725152048@gmail.com> References: <524794479.20140703121338@gmail.com> <20140703180957.GD13710@konrad-lan.dumpdata.com> <1376452421.20140707092147@gmail.com> <1083121389.20140707122233@gmail.com> <623751089.20140718153713@gmail.com> <20140718190942.GG15947@laptop.dumpdata.com> <538610044.20140721111330@gmail.com> <1405940004.25022.10.camel@kazak.uk.xensource.com> <357303711.20140725135638@gmail.com> <1406293821.24842.8.camel@kazak.uk.xensource.com> <1035381797.20140725142116@gmail.com> <1406295478.24842.15.camel@kazak.uk.xensource.com> <53D2609A.4000802@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <53D2609A.4000802@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Andrew Cooper Cc: Ian Campbell , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org Hello Andrew, >>>>> Looking at the code I can't see where bit 22 is being set! >>>> Without seeing you code I've no idea about this (even if I could see it, >>>> I dunno...) >>> Bit 22 is being set in Xen code. >> Hopefully someone who knows the x86 PV stuff can chime in then, I looked >> but can't see what this represents. > I suspect this would be: > /* Bit 22 of a 24-bit flag mask. This corresponds to bit 62 of a pte.*/ > #define _PAGE_GNTTAB (1U<<22) > from include/asm-x86/x86_64/page.h > So you are attempting to update a pte which already has a granted page > in it. That's weird as I have only one domU running, so nothing else could have claimed the PCI memory area. The PCI has been passed through as I see the mapping in xenstore. Should I be using a different hypercall to gain access to this memory area? -- Best regards, Simon mailto:furryfuttock@gmail.com