On Tue, 18 Feb 2014 23:04:13 +0100 Laszlo Ersek <ler...@redhat.com> wrote:
> On 02/18/14 17:36, Igor Mammedov wrote: > > On Mon, 17 Feb 2014 09:32:35 +0100 > > Gerd Hoffmann <kra...@redhat.com> wrote: > > > >> On So, 2014-02-16 at 17:53 +0200, Michael S. Tsirkin wrote: > >>> On Fri, Feb 07, 2014 at 01:51:27PM +0100, Igor Mammedov wrote: > >>>> Since introduction of PCIHP, it became problematic to > >>>> punch hole in PCI0._CRS statically since PCI hotplug > >>>> region size became runtime changeable. > >>> > >>> What makes it runtime changeable? > >> > >> machine type. q35 / piix map them at different locations. > >> > >> Also we might want to this also for devices which are > >> runtime-configurable (isa-debugcon, pvpanic, ...). > > I'd convert simple devices that conditionally enabled at > > startup time, from static definition + patching into > > completely dynamically generated when device present. > > For example pvpanic falls in to this category. > > > > That would result in smaller ACPI tables guest has to deal with. > > I could be mistaken, but AFAIR this caused the windows device manager to > pop up in windows? Ie. if you have a windows guest and cold-boot it > twice, once with the device present (generated into ACPI) and once with > the device absent (not generated into ACPI), then you get hardware > changes. Whereas, if the device is always present and you only patch > _STA, then windows doesn't perceive it as a hw change. Is is irrelevant whether device is statically or dynamically created, user will face the same issue and has a choice to install driver or tell windows to ignore device forever. > Do I recall it right?... Device manager pop-ups only once when new device is added to install driver. If later, the device in the same location with the same id appears/disappears, Device manager handles it silently. > > You could argue that "a new device indeed warrants a device manager > popup", but esp. for isa-debugcon and pvpanic, you might want to enable > those opportunistically, without triggering a new hw dialog. Pvpanic > triggering the device manager was exactly what drew frowns, for its > original implementation. IIRC. the above applies to these cases as well, i.e. if you install driver for it then there won't be any pop-ups later. If there is no driver (which is the case) one needs to tell to Device manager to ignore this device, and then there shouldn't be an additional pop-ups later. > Anyway pls. feel free to ignore this comment, it just crossed my mind. > (And of course it's not related to your series.) > > Thanks > Laszlo >