From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: dom0 pvops crash Date: Wed, 27 Jan 2010 11:34:54 -0800 Message-ID: <4B60955E.4080308@goop.org> References: <4B5DF8E5.9040906@goop.org> <1264613173.16526.97718.camel@zakaz.uk.xensource.com> <4B608AE2.1020501@goop.org> <1264619930.2392.248.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1264619930.2392.248.camel@localhost.localdomain> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Ian Campbell Cc: =?ISO-8859-1?Q?Pasi_K=E4rkk=E4?=, "xen-devel@lists.xensource.com" , Ian Jackson , Keir Fraser List-Id: xen-devel@lists.xenproject.org On 01/27/2010 11:18 AM, Ian Campbell wrote: >> That's a thought. It could be generally useful too; highpte should only >> be used in extreme circumstances (to prevent ptes from filling most of >> lowmem), not on every system with highmem. IOW use a generic flag >> rather than make it explicitly Xen-related, then we can set that flag. >> > I think this is the most plausible idea. Need to think about what > criteria would be used to set the flag on native, simply raw RAM size? > i.e. you wouldn't use HIGHPTE on a 4G system, even if CONFIG_HIGHPTE is > enabled, but where would the cut-off be? > > Rather than a flag I guess I'd make a pte_gfp variable which could be > modified to suit. > Well, you could try heuristicing it up, but I suspect a simpler approach is just a variable which is enabled by command line and/or config option. HIGHPTE is an arch-independent concept, but the policy for defaulting it is arch-specific; on x86 it should almost always be off. >> Or we could just put a big fat config dependency in. >> > I'd imagine that seemingly random "depends !XEN" would be unpopular > upstream. > I was thinking the other way around; Xen depends on !HIGHPTE. But a runtime switch would be just as good. J