Hi Wolfgang, On Monday 16 May 2011 12:25 AM, Wolfgang Denk wrote: > Dear Aneesh V, > > In message<1305202276-27784-6-git-send-email-ane...@ti.com> you wrote: >> - Enable I-cache on bootup >> - Enable MMU and D-cache immediately after relocation >> - Do necessary initialization before enabling d-cache and MMU > > Would it be possible to do this even _before_ relocation, so to speed > up memory accesses during relocation? Of course, proper invalidates/ > flushes will be needed before jumping to the RAM address, but I guess > this would save a bit of boot times?
I intentionally kept it after relocation to avoid un-necessary complexities. Relocation is a case of self-modifying code. In Harvard architectures like armv7 there will be coherency issues unless we flush the entire D-cache(range based operation may be equally or more expensive) and invalidate the entire I-cache. So, in effect everything has to be flushed to memory before you jump to the new location. There may be a small advantage because flushing from cache allows for bursting to the DDR where as bursting is not possible when d-cache is disabled. But I think this is not worth the trouble. best regards, Aneesh _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
