Messages in this thread | | | Date | Thu, 11 Sep 2003 18:13:16 +0100 | From | Jamie Lokier <> | Subject | Re: Memory mapped IO vs Port IO |
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Andi Kleen wrote: > My gut feeling is to just fix the drivers to make this runtime switchable > and get rid of the compile time options. > > This would help distributions (who normally want to build conservative > by default, but still allow the users easy tuning without recompilation) > For that it would be nice if a standard module parameter or maybe > sysfs option existed.
Another way to help distributions is to compile those drivers twice, once for each access type. There aren't all that many drivers that need it.
> The overhead of checking for PIO vs mmio at runtime in the drivers > should be completely in the noise on any non ancient CPU (both MMIO > and PIO typically take hundreds or thousands of CPU cycles for the bus > access, having an dynamic function call or an if before that is makes > no difference at all)
Ah, but what about the ancient CPUs?
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