Dear Sergey Yanovich, > Dear Marek Vasut, > > On Tue, 2013-05-21 at 12:54 +0200, Marek Vasut wrote: > > SRAM is just the in-CPU bit of fast RAM. What do you mean by > > "battery-backup" ? > > Yes, you are right. It is 'for high speed code or data storage preserved > during low-power states' using a quote from PXA270 EMTS (top of page 1). > Battery-backup is optional. I mixed PXA270 and LP-8x4x specs.
Yes, it's just an in-CPU RAM. > > > It can be used as a ultra-fast persistent > > > storage in OS. Wasting a quater of it just to boot the system isn't the > > > best choice. > > > > The SRAM is used for stack in U-Boot until you leave board_init_f, then > > the stack is relocated to DRAM. The OS can use SRAM as needed, U-Boot is > > no longer operational once you load subsequent OS. What's the problem? > > 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? Still, the SRAM/DCache is only used until you leave board_init_f(), then it's all DRAM. Best regards, Marek Vasut _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot