From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jerone Young Subject: Re: [PATCH] supporting non-NX/XD capable processors on x86_64 xenlinux Date: Thu, 18 Aug 2005 10:39:09 -0500 Message-ID: <1124379549.7723.1.camel@thinkpad> References: <7F740D512C7C1046AB53446D3720017304E98EE3@scsmsx402.amr.corp.intel.com> <8cdff1e4320b05b5c89260ad99f23898@cl.cam.ac.uk> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <8cdff1e4320b05b5c89260ad99f23898@cl.cam.ac.uk> 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: Jerone Young , xen-devel@lists.xensource.com, "Nakajima, Jun" List-Id: xen-devel@lists.xenproject.org On Thu, 2005-08-18 at 16:09 +0100, Keir Fraser wrote: > On 18 Aug 2005, at 15:15, Nakajima, Jun wrote: > > > > > One obvious reason is: xen-specific drivers are using __PAGE_KERNEL > > (and > > they don't exist in the native Linux). If xen_contig_memory, for > > example, does not work, it won't boot... Fixing xen_contig_memory did > > not fix the booting problem as long as I remember? > > Yeah, I see what you mean. I've just applied a patch that cleans up the > few remaining bad spots where we weren't using pfn_pte() or > pfn_pte_ma() constructors. I can now boot okay even with NX/XD disabled > in Xen. > > By the way -- from what I've seen of this NX/XD discussion so far, it > sounds like even if CPUID says that NX/XD is supported, and you set the > EFER.NXE bit, the BIOS can still cause this to be ignored! If I remember correctly (will create a patch shortly to make 100% sure). If the option is off in the BIOS than NX bit will not show up as a CPU feature flag. And of course once it's on in the bios then it does. > Is this true > and, if so, what will happen if you try to use NX/XD anyway? i.e., will > the bit be ignored, or will its use cause a page fault? > > -- Keir > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel > -- Jerone Young IBM Linux Technology Center jyoung5@us.ibm.com 512-838-1157 (T/L: 678-1157)