[Qemu-devel] Re: [PATCH v6 07/12] pcie/hotplug: introduce pushing attention button command

[Isaku Yamahata <yamahata@valinux.co.jp>]

On Wed, Oct 20, 2010 at 12:00:11PM +0200, Michael S. Tsirkin wrote:
> On Wed, Oct 20, 2010 at 05:18:56PM +0900, Isaku Yamahata wrote:
> > glue pcie_push_attention_button command.
> > 
> > Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
> 
> So as a high level command, I think we need to
> think about how to tie this into pci_add/pci_del.
> Right?

Maybe or maybe not.
I'm not sure it's a good idea to tie it to pci_add/pci_del
in the first place.
The specification says only that pushing the button is just to
initiate the hot-plug operation. It means only a notification.
The spec says nothing about the concrete action from OS when
the button is pushed. It's up to OS.

For example.
OS may start to probe the slot.
OS may start to quiescence the device.
OS is allowed to ignore the notification. 
OS may propagate the notification to the management software,
and it would pop up the dialog to the user for further operation.


> As a low level command, this is not really useful unless
> there is an event on LED status change and a way
> to get info on LED status.
> Right?

No. Guest OS can provide users those infos, and Linux does
via sysfs. So there already is a way to know LED status.
This is the reason why LED status change event stuff has low
priority in my TODO list.
-- 
yamahata