[SeaBIOS] [PATCH] boot: add serial-friendly alternatives for invoking the boot menu

[Kevin O'Connor]

Hi Paolo,

Sorry for the delay in responding.

On Thu, Mar 05, 2015 at 10:13:30AM +0100, Paolo Bonzini wrote:
> On 04/03/2015 22:42, Kevin O'Connor wrote:
> > On Wed, Mar 04, 2015 at 05:57:02PM +0100, Paolo Bonzini wrote:
> >> F11 and F12 are trapped by some terminal emulators, and sgabios does
> >> not always recognize function keys very well.
> >>
> >> Real-world machines often provide replacements for function keys for
> >> use on the serial console: ESC+1...ESC+0 for F1...F10, ESC+SHIFT+1 and
> >> ESC+SHIFT+2 for F11...F12.  Accept all of them, which can be useful in
> >> case the user has set boot-menu-key.
> > 
> > Thanks.  Did you encounter this problem with QEMU or on a real machine
> > with coreboot?
> 
> With QEMU.
> 
> > Out of curiosity, is there a reason why one can't modify
> > boot-menu-key/boot-menu-message for those machines that don't support
> > F12?
> 
> The trivial reason is that right now, QEMU doesn't support customizing
> the menu key and message (also there are several management layers
> between QEMU and the user, such as libvirt/oVirt/OpenStack, and you'd
> have to add support in all of them).
> 
> But more important, which keys are and are not available depends on the
> client, not on the server.  So for VNC all keys work but on at least a
> viewer F8 is inconvenient because it brings up a menu (thankfully one
> item in the menu is "Send F8"); for the serial console on a Unix machine
> F12 is okay but F11 might bring the terminal full screen; on older Mac
> OS X machine F9-F12 were intercepted by the OS, but on newer OS X
> releases function keys are basically gone for good.  A configuration
> that always works might be broken by the addition of a new client.

The above makes sense.  The F12 key comes from Bochs bios.  Given the
difficulties in using F-keys (on QEMU as well as on real machines) I
wonder if we should just change the SeaBIOS default to ESC?

I don't like changing the default message to "Press ESC+@ or F12 for
boot menu." as I think the description becomes confusing when multiple
options are given.  So, ESC+@ could be a hidden feature, but
admittedly that's not a great option.  Otherwise the technical parts
of the patch looks okay to me.

-Kevin