[SeaBIOS] SeaBIOS recognising USB 3.0 on boot works - partly

Kevin O'Connor kevin at koconnor.net
Sat Dec 19 02:18:34 CET 2015


On Sat, Dec 19, 2015 at 01:51:15AM +0100, Peter Stuge wrote:
> Kevin O'Connor wrote:
> > > Doesn't it effectively take the same amount of wall clock time?
> ..
> > If you're asking if current state vs unregistering/delaying would take
> > the same wall time - thinking about that now, it might be true.
> 
> Right - that's what I meant. I think it will, because ..
> 
> 
> > I guess the implementaiton and how things like CONFIG_THREADS=n are
> > handled would determine that.
> 
> .. by the time the menu is shown and/or SeaBIOS boots automatically
> there is only one thread running anyway, right?
> 
> (Or is this where I am missing something?)

Thinking about this further, USB hubs are the real issue.  In theory,
a hub could have the same issue of being detected initially as USB2
and then later as USB3.  In this situation, delaying does fix the
issue, but it adds more wall time as then one can't query the devices
downstream of the hub until after the delay.  Unregistration doesn't
work well with hubs, because it's complicated to determine
connectivity for devices downstream of a hub that's been removed, and
because it would require different code for unregistration of mice and
keyboards.

-Kevin



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