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

[Paolo Bonzini]

On 11/03/2015 18:24, Kevin O'Connor wrote:
> On Wed, Mar 11, 2015 at 05:42:18PM +0100, Paolo Bonzini wrote:
>> I have no problem with changing the key; the problem I have with ESC is
>> that I'm going to add F12 for network boot, and then I would like ESC+@
>> to trigger network boot.  ESC for the boot menu would clash.  With my
>> full patches, the default message would be like this:
> 
> Can you explain that "network boot" feature further?

It prioritizes NIC option ROMs over other options, trying all network
cards before falling back to HD, CD/DVD and non-NIC option ROMs.

It's a common feature on a real machine, to the point that the SMBIOS
tables have a special bit for "network boot can be done with F12".  This
makes sense mostly for Coreboot, though some people requested it on
virtual machines as well.

> I think the message should be
> as succinct as possible - hit this key to stop the default boot -
> otherwise the default boot is going to happen.  I don't think we
> should make that initial prompt any more complex.  Once the user stops
> the default boot (by hitting ESC, F12, whatever) then a more detailed
> explanation and more detailed options can be provided.

What about this:

- for now, change the default key to "ESC" and the default message to
"Press ESC for boot menu".

- in my next round of patches, add "Press N for network boot" in the
boot menu.

- also in my next round of patches, support the F12 key for direct
network boot but keep it "secret".  It's the same as real machines
anyway.  Maybe support ESC+@ in addition to ESC+N too, but that seems
overengineered.

> Everyone seems to want something slightly different for the boot
> splash, which is why there are so many fw_cfg/cbfs entries that allow
> customization of it.  I'm leery of adding more complexity to it,
> because I fear that's going to lead to even more complexity as users
> desire further customization.

I understand.

Paolo