On 2017-05-18 16:59, Lothar Waßmann wrote: > Manfred Schlaegl <manfred.schla...@ginzinger.com> wrote: > >> On 2017-05-17 06:13, Lokesh Vutla wrote: >>> >>> >>> On Tuesday 16 May 2017 07:59 PM, Manfred Schlaegl wrote: >>>> On 2017-05-11 08:53, Lokesh Vutla wrote: >>>>> >>>>> >>>>> On Wednesday 10 May 2017 07:11 PM, Manfred Schlaegl wrote: >>>>>> Using u-boot-2017.05 on i.MX6UL we ran into following problem: >>>>>> Initially U-Boot could be started normally. >>>>>> If we added one random command in configuration, the newly generated >>>>>> image hung at startup (last output was DRAM: 256 MiB). >>>>>> >>>>>> We tracked this down to a data abort within relocation (relocated_code). >>>>>> > [...] >>>> In a good case (rel_dyn_start aligned to 8 byte), u-boot is starting up >>>> normally >>>> rel_dyn_start is 0x8785FC28 >>>> rel_dyn_end is 0x87857BD0 >>>> A dump of this memory area shows no abnormality >>>> >>>> In a bad case (same source, but rel_dyn_start aligned to 4 byte), the data >>>> abort happens >>>> rel_dyn_start is 0x8785FC24 >>>> rel_dyn_end is 0x87857BCC >>>> So we have the same size of 32856 bytes but a memory dump showed exactly >>>> one difference, which is >>>> very interesting: >>>> >>>> At offset 0x610 (relative to rel_dyn_start) we have following difference >>>> -00000610 30 3e 80 87 17 00 00 00 34 3e 80 87 00 00 00 00 >>>> |0>......4>......| >>>> +00000610 30 3e 80 87 17 00 00 00 00 00 00 00 17 00 00 00 >>>> |0>..............| >>> >>> Looks like someone is corrupting the data(assuming). Is it all 0's just >>> at this location or continuously after this? >> >> No. Above diff is the only difference of the good and bad case in memory >> located between >> rel_dyn_start and rel_dyn_end. >> >> To see if it might be a corruption I compared the the rel_dyn with the >> created u-boot.img and >> found the same difference >> -00000610 30 3e 80 87 17 00 00 00 34 3e 80 87 17 00 00 00 >> |0>......4>......| <--- generated image >> +00000610 30 3e 80 87 17 00 00 00 00 00 00 00 17 00 00 00 >> |0>..............| <--- memory dump >> >> So it must be some kind of corruption. >> > This can be caused by a static variable, that is written to prior to > relocation. Since the .rel section overlays the .bss section, the write > to a variable in the BSS will corrupt the relocation data. >
Yes! That's it! Using a watchpoint I tracked the corruption down to an early write to a static variable in our custom code. So finally: The whole thing was a problem in a custom modification and was solved there. It has no implication on u-boot itself. Thanks a lot for your help and time! Best regards Manfred _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
