On Wed, 31 Jul 2019 at 07:33, David Gibson <da...@gibson.dropbear.id.au> wrote: > > On Mon, Jul 29, 2019 at 04:56:30PM +0200, Damien Hedde wrote: > > Signed-off-by: Damien Hedde <damien.he...@greensocs.com> > > +For Devices and Buses there is also the corresponding helpers: > > +void device_reset(Device *dev, bool cold) > > +void bus_reset(Device *dev, bool cold) > > What's the semantic difference between resetting a bus and resetting > the bridge device which owns it?
We should definitely explain this in the documentation, but consider for instance a SCSI controller. Resetting the SCSI controller puts all its registers back into whatever the reset state is for the device, as well as resetting everything on the SCSI bus. Resetting just the SCSI bus resets the disks and so on on the bus, but doesn't change the state of the controller itself, which remains programmed with whatever state the guest has set up. PCI has a similar distinction between resetting the controller and resetting the bus. Note that we have this distinction in the current APIs too: qbus_reset_all() vs qdev_reset_all(). thanks -- PMM
