From: Pavel Machek Subject: Re: [PATCH 16/16 v6] PCI: document the new PCI boot parameters Date: Sun, 9 Nov 2008 15:19:09 +0100 Message-ID: <20081109141909.GA2458@ucw.cz> References: <20081022083809.GA3757@yzhao12-linux.sh.intel.com> <20081022084531.GP3773@yzhao12-linux.sh.intel.com> <20081106043235.GA30292@kroah.com> <4913AA03.5060807@intel.com> <20081107025032.GA12824@kroah.com> <4913B8A5.5010806@intel.com> <20081107061603.GC3860@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Zhao, Yu" , "linux-pci@vger.kernel.org" , "achiang@hp.com" , "grundler@parisc-linux.org" , "mingo@elte.hu" , "jbarnes@virtuousgeek.org" , "matthew@wil.cx" , "randy.dunlap@oracle.com" , "rdreier@cisco.com" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "virtualization@lists.linux-foundation.org" To: Greg KH Return-path: Content-Disposition: inline In-Reply-To: <20081107061603.GC3860@kroah.com> Sender: linux-pci-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Hi! > >>> If we do resource rebalance after system is up, do you think there is any > >>> side effect or impact to other subsystem other than PCI (e.g. MTRR)? > >> I don't think so. > >>> I haven't had much thinking on the dynamical resource rebalance. If you > >>> have any idea about this, can you please suggest? > >> Yeah, it's going to be hard :) > >> We've thought about this in the past, and even Microsoft said it was > >> going to happen for Vista, but they realized in the end, like we did a > >> few years previously, that it would require full support of all PCI > >> drivers as well (if you rebalance stuff that is already bound to a > >> driver.) So they dropped it. > >> When would you want to do this kind of rebalancing? Before any PCI > >> driver is bound to any devices? Or afterwards? > > > > I guess if we want the rebalance dynamic, then we should have it full -- > > the rebalance would be functional even after the driver is loaded. > > > > But in most cases, there will be problem when we unload driver from a hard > > disk controller, etc. We can mount root on a ramdisk and do the rebalance > > there, but it's complicated for a real user. > > > > So looks like doing rebalancing before any driver is bound to any device is > > also a nice idea, if user can get a shell to do rebalance before built-in > > PCI driver grabs device. > > That's not going to work, it needs to happen before any PCI device is > bound, which is before init runs. We could run shell from early initrd... And PCI is not required for initrd, right? (Ok, I guess this is in we could do it but is it worth the cost?-category...) -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html