David P. Reed wrote:
Just a thought for a way to fix the "very early" timing needed to set up udelay to work in a way that works on all machines. Perhaps we haven't exploited the BIOS enough: The PC BIOS since the PC AT (286) has always had a standard "countdown timer" way to delay for n microseconds, which as far as I know still works. This can be used to measure the speed of a delay loop, without using ANY in/out instructions directly (the ones in the BIOS are presumably correctly delayed...).
If we enter from the 32-bit entrypoint, we already don't have access to the BIOS, though.
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