Subject: Re: [PATCH] x86_64: fix problems due to use of "outb" to port 80 on some AMD64x2 laptops, etc.
Newsgroups: gmane.linux.kernel
Date: 2007-12-14 18:02:57 GMT (50 weeks, 3 days, 4 hours and 59 minutes ago)
Ingo Molnar wrote: > > wow, cool fix! (I remember that there were other systems as well that > are affected by port 0x80 muckery - i thought we had removed port 0x80 > accesses long ago.) > > how about the simpler fix below, as a first-level approach? We can then > remove the _p in/out sequences after this. > I believe this will suffer from the issue that was raised: this will use udelay() long before loop calibration (and no, we can't just "be conservative" since there is no "conservative" value we can use.) Worse, I suspect that at least the PIT, which may need to be used for udelay calibration, is one of the devices that may be affected. I have seen the Verilog for a contemporary chipset, and it can only access the PIT once per microsecond -- this actually has to do with the definition of the PIT; some of the PIT operations are ill-defined if allowed at a higher frequency than the PIT clock. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo <at> vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/