2017-11-30 17:30 GMT+08:00 Arnd Bergmann <arnd@xxxxxxxx>: > On Thu, Nov 30, 2017 at 6:48 AM, Greentime Hu <green.hu@xxxxxxxxx> wrote: >> 2017-11-30 4:27 GMT+08:00 Arnd Bergmann <arnd@xxxxxxxx>: >>> On Wed, Nov 29, 2017 at 3:10 PM, Greentime Hu <green.hu@xxxxxxxxx> wrote: >>>> 2017-11-29 19:57 GMT+08:00 Arnd Bergmann <arnd@xxxxxxxx>: > >>> When you put them in a sorted list like I mentioned for simplicity, you >>> could reduce the confusion by naming them differently, e.g. >>> CONFIG_CPU_N10_OR_NEWER. >>> >>> Having only the CPU_CACHE_NONALIASING option is fine if you >>> never need to make any other decisions based on the CPU core >>> type, but then the help text should describe specifically which cases >>> are affected (N10/N13/D13 with 4K page size), and you can decide to >>> hide the option and make it always-on when using 8K page size. >>> >>> Arnd >> >> >> Hi, Arnd: >> >> I think I can use this name "CPU_V3" for all nds32 v3 compatible cpu. >> It will be implemented like this. > > I think I'm still a bit confused about the relation between CPU cores > and architecture levels. Is it correct to say that there are orthogonal, > and that you can have e.g. an N10 core implementing either nds32v2 > or nds32v3? > Yup, we did having N10 cores are implementing either nds32v3 or nds32v2, but nds32v2 are not used anymore. We can assume every nds32 cores are v3. > There is nothing wrong with that of course, it's just not what I > expected from having worked with other architectures. > > I also see that GCC has no pipeline specific optimizations for > specific cores, it just understands the differences between the > architecture levels, so at least today there is way to pass e.g. > "-march=nds32v2 -mtune=d15" to generate code that would > work on both v2 and v3 but be optimized for d15. Thanks. We will work on that. >> config HWZOL >> bool "hardware zero overhead loop support" >> depends on CPU_D10 || CPU_D15 >> default n >> help >> A set of Zero-Overhead Loop mechanism is provided to reduce the >> instruction fetch and execution overhead of loop-control instructions. >> It will save 3 registers($LB, $LC, $LE) for context saving if say Y. >> You don't need to save these registers if you can make sure your user >> program doesn't use these registers. >> >> If unsure, say N. >> >> config CPU_CACHE_NONALIASING >> bool "Non-aliasing cache" >> depends on !CPU_N10 && !CPU_D10 >> default n >> help >> If this CPU is using VIPT data cache and its cache way size is larger >> than page size, say N. If it is using PIPT data cache, say Y. >> >> If unsure, say N. > > This looks ok, yes, but as Geert said, it would seem more intuitive to > write it as > > config CPU_CACHE_ALIASING > bool "Aliasing VIPT cache" > depends on CPU_N10 || CPU_D10 > >> choice >> prompt "CPU type" >> default CPU_V3 >> config CPU_N15 >> bool "AndesCore N15" >> select CPU_CACHE_NONALIASING >> config CPU_N13 >> bool "AndesCore N13" >> select CPU_CACHE_NONALIASING if ANDES_PAGE_SIZE_8KB >> config CPU_N10 >> bool "AndesCore N10" >> config CPU_D15 >> bool "AndesCore D15" >> select CPU_CACHE_NONALIASING >> config CPU_D10 >> bool "AndesCore D10" >> config CPU_V3 >> bool "AndesCore v3 compatible" >> select ANDES_PAGE_SIZE_4KB >> endchoice > > Two points here: > > - Generally you should not mix 'select' and 'depends on' like this. > Either you make the cache aliasing a user visible option that > uses 'depends on' with a combination of CPU cores, or you > make it a hidden option (with no string after the "bool" keyword) > that always gets selected from the per-cpu options. > > - There is a little-known trick with choice statements that allows > you to use 'tristate' instead of 'bool' in the choice. In that case, > you can enable multiple options together as long as all of them > are 'm'. > > Arnd Thanks. CPU_CACHE_ALIASING is more intuitive. I will apply it. -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
