Trying to boot custom kernel on Wink Hub (i.MX28)

[Rogan Dawes]

I tried to follow your suggestion, but so far I have been unsuccessful.

I cloned Linus' latest source code, and then did:

make ARCH=arm mxs_defconfig
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi-
cat arch/arm/boot/zImage ./arch/arm/boot/dts/imx28-evk.dtb >
arch/arm/boot/zImage_with_dtb
cd arch/arm/boot
mkimage -T kernel -A arm -O linux -a 0x40008000 -e 0x40008000 -C none -d
./zImage_with_dtb uImage_with_dtb

then copied onto the Wink hub and did:

flash_erase /dev/mtd4 0 0
nandwrite -p -m /dev/mtd4 uImage_with_dtb
reboot

I then interrupted u-boot, and had to update the number of bytes read from
the mtd4 partition (was 0x00400000, now 0x00600000), as the new kernel was
about 4 times larger than the vendor kernel, and I was getting checksum
errors due to only partial read of the image.

setenv app_boot 'run appboot_args && nand read ${loadaddr} app-kernel
0x00600000 && bootm ${loadaddr}'
run app_boot

NAND read: device 0 offset 0x2b00000, size 0x600000
 6291456 bytes read: OK
## Booting kernel from Legacy Image at 42000000 ...
   Image Name:
   Created:      2023-06-22  21:37:11 UTC
   Image Type:   ARM Linux Kernel Image (uncompressed)
   Data Size:    6279041 Bytes = 6 MiB
   Load Address: 40008000
   Entry Point:  40008000
   Verifying Checksum ... OK
   Loading Kernel Image ... OK

Starting kernel ...

And it stopped there after dumping some garbage to the screen.

I did note that the mxs_defconfig did not define the appended DTB config,
so I updated my .config as follows:

$ grep DTB .config
CONFIG_ARM_APPENDED_DTB=y
CONFIG_ARM_ATAG_DTB_COMPAT=y
CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER=y
# CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND is not set

And rebuilt as above, with no change.

Am I doing something obviously wrong?

Thanks

Rogan





On Sat, 17 Jun 2023 at 16:28, Rogan Dawes <rogan at dawes.za.net> wrote:

> Thank you so much for the response! It is much appreciated!
>
> I do hope to get JTAG working on the Hub v1, and then will be able to try
> to build a modern U-Boot which I can flash.
>
> Regards,
>
> Rogan
>
>
> On Thu, 15 Jun 2023 at 22:01, Fabio Estevam <festevam at gmail.com> wrote:
>
>> Hi Rogan,
>>
>> On Thu, Jun 15, 2023 at 9:00 AM Rogan Dawes <rogan at dawes.za.net> wrote:
>> >
>> > Hi folks,
>> >
>> > I am trying to boot a custom kernel on a Wink Hub v1, which has an
>> i.MX28
>> > CPU, and is running U-Boot (U-Boot 2014.01-14400-gda781c6-dirty (Apr 30
>> > 2014 - 22:35:38)).
>> >
>> > I have tried compiling my own modern kernel and putting it in place of
>> the
>> > vendor (Linux version 2.6.35.3-flex-dvt) kernel on the flash chip, but
>> when
>> > loading, I simply get the expected U-Boot loading messages, but then
>> > nothing at all from the serial port after that.
>> >
>> > I'm trying to figure out where my problem is most likely to be. As far
>> as I
>> > am aware from long-ago poking at U-Boot, the way that U-Boot passes
>> > arguments to the kernel has changed recently? Previously it was ATAGS,
>> and
>> > now it expects a Device Tree Blob? Might this explain the failure to
>> boot
>> > that I am seeing? And yes, I understand that given that
>>
>> Yes, to boot a modern kernel, you need to generate a devicetree for
>> the Wink Hubv1 board.
>>
>> Then you build it and generate a .dtb file.
>>
>> To boot zImage + dtb using an old bootloader that does not support
>> booting dtb,
>> you would need to select the following options in the kernel:
>>
>> CONFIG_ARM_APPENDED_DTB=y
>> CONFIG_ARM_ATAG_DTB_COMPAT=y
>>
>> And then:
>>
>> cat arch/arm/boot/zImage arch/arm/boot/dts/imx28-wink-hub-v1.dtb >
>> zImage_with_dtb
>>
>> And then boot zImage_with_dtb as you do with 2.6.35.
>>
>> Ideally, you should also port a modern U-Boot version, which supports
>> dtb by default and then you don't need the
>> steps above.
>>
>> Take a look at board/freescale/mx28eevk support for a reference.
>>
>> Regards,
>>
>> Fabio Estevam
>>
>