[syslinux] CPU usage while at syslinux boot prompt

[Ferenc Wagner]

"H. Peter Anvin" <hpa at zytor.com> writes:

> 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.

Ah.  But it doesn't sound much worse than asking the user to specify
the base address of the port.  So if the user kindly provides the
correct IRQ number and we point the corresponding vector to an iret
and insert an hlt into the busy loop, is everything set?

Sorry if I'm sounding dense...
-- 
Thanks,
Feri.