Re: [Qemu-devel] Adding more function keys support

[Programmingkid <programmingkidx@gmail.com>]

> On Dec 12, 2017, at 9:34 AM, Daniel P. Berrange <berrange@redhat.com> wrote:
> 
> On Sun, Dec 10, 2017 at 02:10:41AM -0500, Programmingkid wrote:
>> On Macintosh keyboards there is a key called fn that is used to give the
>> function keys more functionality. Does this key exist in the keyboard keys
>> database?
> 
> When you say "Macintosh keyboards" are you talking about the old style
> keyboards with Apple's custom ADB connector, or simply Apple branded
> USB keyboards ? 

USB keyboards.

> 
> If its the latter (USB), then please plug it into a Linux machine, and
> in a text console (ie not X11) run 'showkey' and press this 'fn' key on
> its own and tell me what (if any) hex code gets printed.

There was no response to the fn key.

> 
> Also, under OS-X run this app:
> 
>  https://manytricks.com/keycodes/
> 
> and again let me know what it reports when the fn key is pressed on its
> on.

Yes the Key Codes application does report the fn key being pressed. 

Modifier Change
	Keys:		
	Key Code:	65535 / 0xffff
	Modifiers:	8388864 / 0x800100 ⓘ

Modifier Change
	Keys:		
	Key Code:	65535 / 0xffff
	Modifiers:	256 / 0x100 ⓘ

> Then also do the same but press 'fn' in combination with another function
> key.

The value did not change.

> 
> The key thing we need to understand is whether this magic behaviour of
> the 'fn' key is actually changing what the main function keys send as
> scancodes.

This is hard to figure out. If the function key is mapped to a function like Volume Up, then no event is logged in the Key Codes application. So this probably means the operating system catches the key and does not share it with other applications.

> 
>> Also could keys F16 to F24 (Q_KEY_CODE_F16 to Q_KEY_CODE_F24) be added to
>> the database?
> 
> Those are already defined in keycodemapdb, so we just need to give them
> names in the qapi schema, and then add the name mapping to keycodemapdb.

I have a vague memory of doing something like this a long time ago. Hopefully I can find the path if it exists.