RAM Bit errors after the two boot stages SoCKit Part1

Continued...

problem:

- Sometimes the system hangs with different tracelogs depending on which data was destroyed; the corrupt system comes from bit flips/more than two Bit errors within the RAM which normally means that the calibration should not be successful -> can be seen from memtester (userspace)

- If the same kernel+DTB is copied to the existing SD-Card (replacing the uImage+ DTB on the SD-Card) in combination with the existing preloader and u-boot (old one from Quartus 13.01), everything works fine

finding the bug:

- I’ve tried many things but with no positive result:

- Changed all addresses TEXT_BASE, FDT,… addresses as used with the SD-Card for the SoCKit

Adresses: FDT -> 0x100

uImage -> 0x7FC0

kernel entry point: 0x8000

uboot -> 0x01000040

- I also used some other addresses (suitable addresses) -> did not solve the problem

- Preloader RAM test with SDRAM_TEST_LONG (spl.c) -> no errors

- Own function within the preloader which writes 0xFFFFFFFF and 0x00000000 to the full SDRAM address range + data check --> no errors

- Test on the next bootstage (U-Boot) -> splitted some memory areas into two equal parts and filled them with the same data -> compared against each other to find at minimum one corrupt address with a flipped bit

- No errors, even with high memory and more than 500MB

- Checked data written by the JTAG interface by comparing the MD5 sums (1: after writing the images into RAM during the preloader stage; 2: transferred the same data during the U-Boot stage (manually halted) and checked against the original data for the case that U-Boot is doing something wrong and reconfigures the RAM controller which should not happen) --> no errors --> no overlapping of images within the RAM

- Checked U-Boot settings; compared against SD-Card U-Boot settings which are relevant

- Compared RAM-CTRL register values which the prealoder configures and the same registers from Linux -> no differences-> configuration is still valid

- Compared old Preloader settings (RAM configuration in sdram_config.h) -> not the same as with the current handoff files even if the old project was the base for the current one

- Tried to replace the settings with the old ones-> Preloader RAM check passed but the error are still there

- Tried a different kernel from rocketboards (socfpga), version 3.16 -> same problem

Conclusion: -- the Kernel seems not to be faulty, because it works with the SD-Card

- Maybe there is a problem with U-Boot?

Has anyone seen such a problem?

Has anyone ideas what the problem could be?

Thanks!