Hi,
Just as a follow up, I conclude that U-boot treats flash reads exactly as sdram reads i.e. 32-bit accesses. So its not just about the environment variables. Most of the flash-based U-boot functionality wouldn't work for us unless we modify all the commands that have access to flash e.g md, imiinfo, bootm etc. A hardware fix (an 8-bit bus to our byte-mode flash chip) seems like the right way to go.
Shamile
On Sat, 2004-01-31 at 12:12, Wolfgang Denk wrote:
In message 1075423717.18221.233.camel@localhost.localdomain you wrote:
To get around this, we have a small program which is stored in FPGA bitstream and runs in FPGA on-chip memory (called BRAM). This program copies u-boot binary image from flash to sdram and jumps to it. This allows U-boot to run. However the problem is that the environment variables saved in flash are not being used even though U-boot has been configured with the CFG_ENV_IS_IN_FLASH option turned on. CFG_FLASH_BASE has been set to the flash base address of u-boot and when I use saveenv the environment is saved at the proper offset CFG_ENV_OFFSET. The only thing thats a bit different for my U-boot configuration is that CFG_MONITOR_BASE is set to the sdram base address where U-boot starts executing from instead of being set to CFG_FLASH_BASE.
Normally U-Boot attempts to read the environment when starting from the same position in memory where it will save it to when you issue a "saveenv" command. You will have to modify U-Boot such that the initialization reads from the "fixed" copy in RAM, while "saveenv" saves to the address in flash, performing the 16-bit-expansion needed for your setup. It seems obvious that a plain copy as usuall cannot work on your system.
Best regards,
Wolfgang Denk
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