On Wed, 23 Jun 2010 18:35:55 +0300 Avi Kivity <avi@xxxxxxxxxx> wrote: > On 06/23/2010 06:26 PM, Michael S. Tsirkin wrote: > > > > > >>> > >>> > >>>>>> Shouldn't a reset be equivalent to power cycling? > >>>>>> > >>>>>> > >>>>>> > >>>>> If we did this, driver would need to restore registers > >>>>> such as BAR etc. > >>>>> > >>>>> > >>>>> > >>>> We could save/restore the registers we care about. > >>>> > >>>> > >>> It seems easier to clear registers we care about. > >>> > >> We know the registers we care about, we don't know the ones we don't. > >> > > If/when we use more registers, we can update driver to clear them on start. > > > > The kdump kernel may not load drivers for those extra devices. FLR or another type of reset also has the nice property of bringing the device into a known state. kexec/kdump has always been vulnerable to having devices in partial states when the new kernel loads; would be good to make it more robust. > > >> I'm talking about FLRing all cards, not just those you want to use. > >> > > reset using FLR/PM is complex because of the need to save/restore > > config space. Doing this on a crashing kernel sounds scary. > > > > Well, you only need to save/restore for the devices you use. The rest > you reset and forget. > > I don't really see why copying some config space is crazy. We could push any needed save/restore of core settings and regs into the PCI core like we do for PM. That would save a bunch of driver trouble... -- Jesse Barnes, Intel Open Source Technology Center _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
