Dear Marek Vasut, On Tue, 2013-05-21 at 13:38 +0200, Marek Vasut wrote: > Yes, it's just an in-CPU RAM.
Well, it is not 'just' RAM. It preserves its state during deep sleep and power off modes. > > Anyway, SRAM preserves its state when power is off. Poweroff time could > > be in years with a backup battery. In addition, D-Cache is an order of > > magnitude faster than SRAM (approx. 9 times) for both reads and writes. > > Is there any measurable difference between using DCache and SRAM? Do you have > any evidence that a speedup happens? I haven't done any special profiling. I am just relying on PXA270 EMTS table 6-14. The table says SRAM reads take 9 cycles, writes take 7 cycles. D-Cache operations take 1 cycle. > Still, the SRAM/DCache is only used until you leave board_init_f(), then it's > all DRAM. Yes, the patch as it is will only affects relocation speed and preserve SRAM from corruption. The speed gain can also be applied to uImage copying/unpacking, but that requires deeper understanding than I have at the moment. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot