On Sun, Nov 14, 2021 at 07:06:04PM +0100, Lukas Wunner wrote: > On Sun, Nov 14, 2021 at 12:24:43PM -0500, Michael S. Tsirkin wrote: > > On Sun, Nov 14, 2021 at 05:39:58PM +0100, Lukas Wunner wrote: > > > Why does virtual hardware implement the Attention Button if it's > > > perceived as annoying? Just amend qemu so that it doesn't advertise > > > presence of an Attention Button to get rid of the delay. (Clear the > > > Attention Button Present bit in the Slot Capabilities register.) > > > > Because we want ability to request device removal from outside the > > guest. > > Please elaborate. Does "outside the guest" mean on the host? > How do you represent the Attention Button outside the guest > and route events through to the guest? The usual way, using kvm ioctls. > > > > An Attention Button doesn't make any sense for virtual hardware > > > except to test or debug support for it in the kernel. Just make > > > presence of the Attention Button optional and be done with it. > > > > > > You'll still be able to bring down the slot in software via the > > > "remove" attribute in sysfs. > > > > This requires guest specific code though. Emulating the attention button > > works in a guest independent way. > > It sounds like you're using the Attention Button because it does > almost, but not quite what you want for your specific use case. > Now you're trying to change its behavior in a way that deviates > from the spec to align it with your use case. > > Why don't you just trigger surprise-removal from outside the guest? > > Thanks, > > Lukas Because linux does not handle it well for all devices. Fixing that requires fixing all drivers. -- MST
