[syslinux] CPU usage while at syslinux boot prompt

[H. Peter Anvin]

Ferenc Wagner wrote:
> OK.  But doesn't the BIOS set up such legacy stuff?  As Peter
> suggested, SYSLINUX wouldn't need a real serial interrupt handler, a
> do-nothing routine would be enough to cancel the HLT.  Isn't it so?
> And that would cut most of the busy-waiting.  But I hear that for some
> reason this isn't reliable, and I wonder why.

BIOS does *NOT* set up an interrupt handler for serial ports.  In fact, 
you don't even have a reliable way to know which IRQ to monitor.

	-hpa