Cc: H. Peter Anvin <hpa@...>, Krzysztof Halasa <khc@...>, Rene Herman <rene.herman@...>, Pavel Machek <pavel@...>, Andi Kleen <andi@...>, David P. Reed <dpreed@...>, <linux-kernel@...>, Thomas Gleixner <tglx@...>, Ingo Molnar <mingo@...>
> I really *hate* the idea that access to non-present hardware is used to
Actually its very good practice.
The LPC bus behaviour is absolutely and precisely defined. The timing of
the inb is defined in bus clocks which is perfect as the devices needing
delay are running at a fraction of busclock usually busclock/2.
Older processors did not have a high precision timer so you couldn't
calibrate loop based delays for 1uS.
Port 0x80 is used all over the place for this, not just in Linux but in a
large number of DOS programs and other PC OS's. It's even got specific
hardware support in many of the chipsets so that you can make the latched
last 0x80 write appear on the parallel port for debugging.
Alan
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