Specifically is there a switch or jumper setting to allow it to boot from an alternate uboot provide with the system other than in flash memory?
the text in the UG is quite correct including the Figure above it. The problem is that the word “bank” changes meaning depending on context. Bank per SerDes means one thing. Bank per DIP switch and FPGA logic means address swizzling, which U-Boot doesn’t know about directly and probably shouldn’t know about semantically. U-Boot thinks in flash banks per flash chip specification, not per DIP switch address modification. Flash banks per chip spec however have little meaning for the standard memory map for the Freescale SDK. In practice, the “erase bank” command option is pretty useless and if you work with the NOR flash, I recommend to use the specific hex addressing as documented in the SDK for the standard NOR flash memory map. This is an unambiguous solution.
With respect to DIP switch banks, only bank 0 and 4 really make sense in practice because these settings effectively swap two image sets, the current and the alternate one. When you look at the address map, this does not mean that you swap contiguous flash regions. You swap image sets. Always think in image sets as shown in the NOR flash memory map in the HW configuration section of the Freescale SDK docs for current/alternate.
With respect to your original question, if you want to boot the system properly without having any valid RCW or U-Boot in NOR flash, then your best bet is an SDCARD boot. The DIP switches are shown in the Configuration/Hardware Configuration section of the SDK docs in Table 3 of the P4080DS specific page.
You need to prepare the SD card with a proper RCW, a U-Boot image and an FMan microcode, so that the P4 can properly boot up to a command line so that you can then fix up the NOR again. Good luck.
Hope this helps.
P4080DS supports several banks on local bus via "lbmap". Please seach board User Guide by "lbmap" keyword.
If the flash is completely empty (all banks), than there are other boot options - NAND flash or I2C.
From uboot, I did an 'erase bank 1', which apparently erased the entire 128 MB flash memory. I've spent considerable time reviewing the 'P4080DSUG_RevC.pdf' user's guide document and have tried all of the documented lbmap settings to no avail. The user's guide claims 'NAND Flash is not currently supported on the system board' and provides no instructions on I2C booting.
I'm surprised there is no fail-safe version of uboot provided with the P4080DS.
There is only one flash bank as far as U-Boot's standard flash commands go. The "bank" mechanism used on p4080ds for alternate boot is just a rotation of addresses. There is no specific area of flash that constitutes bank 0, 1, etc.
It is unfortunate that the P4080DS User's Guide contains the following:
To me, this implies the P4080DS flash memory is segmented into banks and one wouldn't expect the uboot 'erase bank 1' command to erase all of flash memory. In any case, I would still appreciate a yes/no answer to my original question. Thanks.
What should be Dip Switch settings in order to boot from SD card? Assume that SD Card has required files to boot target?
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