On Wed, Jun 23, 2010 at 06:15:20PM +0300, Avi Kivity wrote: > On 06/23/2010 05:43 PM, Michael S. Tsirkin wrote: >> >> >>> If we don't already do so, we >>> should probably FLR anything that moves when a kexec kernel starts. >>> >> Probably only whatever we want to use. But whether this will make it >> more, or less robust, is an open question. >> > > I'm thinking of a sound card left on (maybe not something you have in > kdump scenarios) or an industrial controller. Those cards have side > effects and you want to quiesce them even if you don't know what they > are.
clearing bus master should be enough for that. we still run the risk of hanging the kernel if the device is hung, though. >> >>>>> 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. > 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. >> It's also too late >> now: changing behaviour will break old drivers. >> > > Why? the FLR is triggered by the guest kernel, so all drivers will be > aware it was FLRed. Not for FLR. Too late to reset on PA write. > -- > error compiling committee.c: too many arguments to function _______________________________________________ Virtualization mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/virtualization
