using the same rootfs for different ARM SOCs

Question

I'm trying to use userspace built for i.mx53 on a identical board with i.mx6. The i.mx6 board differs only in the CPU used. I built a new kernel and appropriate DTB, I can load it with uboot and it starts fine. However, when I try to use the rootfs I had for i.mx53 board I get a following jffs error:

jffs2: inconsistent device description

which has something to do with flash OOB not containing valid information. I write the rootfs into a flash partition with the nand write.trimffs command. Do I need to initialize the OOB somehow? I don't remember doing it on the old board. Where can this error come from?

You are sure all peripheral modules and the external connections/devices are absolutely identical? — too honest for this site, Jul 22 '15 at 22:39
Yes, I designed the board. Besides the problem seems to come down only the CPU and flash, the rest doesn't really matter. — moorray, Jul 23 '15 at 21:46

score 0 · Answer 1 · answered Jul 25 '15 at 11:37

Turns out i.MX6 NAND controller (gpmi driver) uses entire OOB space for ECC and JFFS2 cannot fit it's markers there. It is possible to communicate to the kernel weaker requirements for ECC based on NAND chip specification and use fsl,use-minimum-ecc device tree option to save up some OOB. However, u-boot does not seem to have support for such ECC reconfiguration and it becomes impossible to use NAND in both bootloader and Linux. Probably the best way forward in this situation is to ditch JFFS2 and use UBIFS instead.

Note: I've seen JFFS2 patches which make it not use OOB, but haven't tried them.

using the same rootfs for different ARM SOCs

1 Answers1