Messages in this thread | | | Subject | Re: [PATCH 7 of 20] ipath - misc driver support code | From | Roland Dreier <> | Date | Thu, 09 Mar 2006 15:13:24 -0800 |
| |
> +/** > + * ipath_unordered_wc - indicate whether write combining is ordered > + * > + * Because our performance depends on our ability to do write combining mmio > + * writes in the most efficient way, we need to know if we are on an Intel > + * or AMD x86_64 processor. AMD x86_64 processors flush WC buffers out in > + * the order completed, and so no special flushing is required to get > + * correct ordering. Intel processors, however, will flush write buffers > + * out in "random" orders, and so explict ordering is needed at times. > + */ > +int ipath_unordered_wc(void) > +{ > + return boot_cpu_data.x86_vendor == X86_VENDOR_INTEL; > +}
This is kind of theoritical, but it seems to me that it would be safer to write this as
int ipath_unordered_wc(void) { return boot_cpu_data.x86_vendor != X86_VENDOR_AMD; }
after all, Via is probably going to have an x86-64 CPU one of these days, and I doubt you've checked that their WC flush is ordered.
- R. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |