Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops

Alan Cox
2007-12-08T20:32:46Z

> In any case, my machine does not have an ISA bus. Why should it? It's
> a laptop!

Yes it does. The branding spec said "No ISA bus" so it was renamed "LPC"
and hidden internally, but its alive and well.

> has already serviced the bus and delivered data! Why put many
> microseconds into the bus, locking out other ISA transactions (and PCI
> maybe too) with an out to port 80?

Historically processors didn't have a high precision time source so it
was the normal way to do it on all PC operating systems

> Some of the code in linux is really nice, really clean, really
> well-thought out. Some is ... well, I'm not trolling for a fight.

Like all things, it doesn't always age well 8)