Alan Cox wrote: >> This is a timing issue, isn't it? How are we synchronising, other than >> by delaying for a (bus-dependant) period? The characteristics of each >> bus are known so a number can be assigned for "one bus cycle", without >> having to use the bus. >> > > The characteristics of the bus are not known. It could be anything > between 6 and about 16MHz.
In the early days of clone PCs, as you know but perhaps many on this list might not, the bus speed could be changed, but this was user-selectable. For such a machine, delay values can be pre-calculated for each bus speed, and a kernel parameter set accordingly. Or are you saying that the characteristics of the bus on a given machine vary for reasons other than user selection? The fact that busses run at different speeds on different machines is not a problem because the delay value can be determined for each given machine. The question is, for a given machine, can we determine a delay value instead of using a junk I/O? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
