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Bad Linux ARM zImage magic! on iMX6UL

Question asked by Mitch Hodges on Sep 22, 2016
Latest reply on Sep 22, 2016 by Mitch Hodges

Hi,

 

We've built a few custom boards based on the iMX6UL with eMMC on SDIO2.  We've had a CM build a few boards for us which are being validated before we build a larger run of PCBs.

 

The first set of boards turned on no issue, and a console log on initial boot looks good:

U-Boot 2015.04-imx_v2015.04_4.1.15_1.0.0_ga+gd7d7c43 (Sep 09 2016 - 19:01:59)

CPU: Freescale i.MX6UL rev1.1 at 396 MHz
CPU: Temperature 36 C
Reset cause: POR
Board: MX6UL 14x14 EVK
DRAM: 512 MiB
MMC: FSL_SDHC: 0, FSL_SDHC: 1
*** Warning - bad CRC, using default environment

Display: TFT43AB (480x272)
Video: LCDIF@0x21c8000 is fused, disable it
In: serial
Out: serial
Err: serial
switch to partitions #0, OK
mmc1(part 0) is current device
Net: Ethernet@0x20b4000 is fused, disable it
FEC1 MXC: board_eth_init:failed
No ethernet found.
Normal Boot
Hit any key to stop autoboot: 0
switch to partitions #0, OK
mmc1(part 0) is current device
switch to partitions #0, OK
mmc1(part 0) is current device
reading boot.scr
** Unable to read file boot.scr **
reading zImage
6649752 bytes read in 163 ms (38.9 MiB/s)
Booting from mmc ...
reading imx6ul-14x14-evk-btwifi.dtb
34507 bytes read in 18 ms (1.8 MiB/s)
Kernel image @ 0x80800000 [ 0x000000 - 0x657798 ]

 

Interestingly, we have 2 more panels of boards which do the following:

U-Boot 2015.04-imx_v2015.04_4.1.15_1.0.0_ga+gd7d7c43 (Sep 14 2016 - 12:12:28)

CPU: Freescale i.MX6UL rev1.1 at 396 MHz
CPU: Temperature 35 C
Reset cause: POR
Board: MX6UL 14x14 EVK
DRAM: 512 MiB
MMC: FSL_SDHC: 0, FSL_SDHC: 1
*** Warning - bad CRC, using default environment

Display: TFT43AB (480x272)
Video: LCDIF@0x21c8000 is fused, disable it
In: serial
Out: serial
Err: serial
MMC: no card present
Net: Ethernet@0x20b4000 is fused, disable it
FEC1 MXC: board_eth_init:failed
No ethernet found.
Normal Boot
Hit any key to stop autoboot: 0
MMC: no card present
MMC: no card present
MMC: no card present
Booting from net ...
No ethernet found.
No ethernet found.
Bad Linux ARM zImage magic!

 

What does not make sense at all is that we've successfully flashed the same image over USB into both boards, and burned efuses the same in both boards with the following:

 

fuse prog 0 5 00000860
fuse prog 0 6 00000010

Uboot is also coming up, so we know we have something successfully done with eMMC...

 

Any ideas what may be going on here?  We've replaced eMMC and reflashed.  We've also used the DDR stress tester and see that pass well.  Definitely something in HW, but nothing is really making sense here...

 

Thanks,

-Mitch

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