From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Arcangeli Subject: Re: [PATCH] reserved-ram for pci-passthrough without VT-d capable hardware Date: Wed, 30 Jul 2008 16:38:26 +0200 Message-ID: <20080730143826.GI11494@duo.random> References: <1214232737-21267-1-git-send-email-benami@il.ibm.com> <20080729125312.GL11494@duo.random> <20080729131735.GM30344@one.firstfloor.org> <200807301150.44266.amit.shah@qumranet.com> <20080730135846.GB11494@duo.random> <489077A6.7090105@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Amit Shah , Andi Kleen , benami@il.ibm.com, Avi Kivity , Andrew Morton , kvm@vger.kernel.org, aliguori@us.ibm.com, allen.m.kay@intel.com, muli@il.ibm.com, linux-mm@kvack.org, tglx@linutronix.de, mingo@elte.hu To: Dor Laor Return-path: Received: from host36-195-149-62.serverdedicati.aruba.it ([62.149.195.36]:46366 "EHLO mx.cpushare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752314AbYG3Oib (ORCPT ); Wed, 30 Jul 2008 10:38:31 -0400 Content-Disposition: inline In-Reply-To: <489077A6.7090105@qumranet.com> Sender: kvm-owner@vger.kernel.org List-ID: On Wed, Jul 30, 2008 at 05:16:06PM +0300, Dor Laor wrote: > In addition KVM is used in embedded too and things are slower there, we > know of a specific use case (production) that demands > 1:1 mapping and can't use VT-d Since you mentioned this ;), I take opportunity to add that those embedded usages are the ones that are totally fine with the compile time passthrough-guest-ram decision, instead of a boot time decision. Those host kernels will likely have RT patches (KVM works great with preempt-RT indeed) and in turn the compile time ram selection is the least of their problems as you can imagine ;). So you can see my patch as an embedded-build option, similar to "Configure standard kernel features (for small systems)" and no distro is shipping new kernels with that feature on either. Than if we decide 1:1 should have larger userbase instead of only the people that knows what they're doing (i.e. 1:1 guest can destroy linux-hypervisor) we can always add a bit of strtol parsing to 16bit kernelloader.