[Buildroot] Issue with BeagleBone Black Rev C - 4GB Flash - Pre-installed Debian

Thomas Petazzoni thomas.petazzoni at free-electrons.com
Wed Jul 23 19:58:39 UTC 2014


Dear Neil Fincham,

On Wed, 23 Jul 2014 09:05:46 +1200, Neil Fincham wrote:

> Has anyone tried the new BeagleBone Black Rev C ?

Yes.

>  I am having an issue
> where it will not boot any of my (working on the Rev B) images.  It look
> like to my untrained eye that the new debian uEnv.txt scans the SD for a
> valid uEnv.txt (with uenvcmd declared in it) and when it does not find it,
> it boots from mmc.
> 
> The boot from the serial looks like this;-
> 
> U-Boot 2014.04-00015-gb4422bd (Apr 22 2014 - 13:24:29)
> 
> I2C:   ready
> DRAM:  512 MiB
> NAND:  0 MiB
> MMC:   OMAP SD/MMC: 0, OMAP SD/MMC: 1
> *** Warning - readenv() failed, using default environment
> 
> Net:   <ethaddr> not set. Validating first E-fuse MAC
> cpsw, usb_ether
> Hit any key to stop autoboot:  0
> gpio: pin 53 (gpio 53) value is 1
> mmc0 is current device
> gpio: pin 54 (gpio 54) value is 1
> SD/MMC found on device 0
> reading uEnv.txt
> Checking if uenvcmd is set ...
> 
> uenvcmd was not defined in uEnv.txt ...
> gpio: pin 56 (gpio 56) value is 0
> gpio: pin 55 (gpio 55) value is 0
> gpio: pin 54 (gpio 54) value is 0
> mmc1(part 0) is current device
> gpio: pin 54 (gpio 54) value is 1
> SD/MMC found on device 1
> reading uEnv.txt
> 1430 bytes read in 7 ms (199.2 KiB/s)

Here it has properly found an uEnv.txt.

> gpio: pin 55 (gpio 55) value is 1
> Loaded environment from uEnv.txt
> Importing environment from mmc ...
> Checking if uenvcmd is set ...

From which it executes the variable 'uenvcmd'.

> gpio: pin 56 (gpio 56) value is 1
> Running uenvcmd ...
> reading zImage
> 3717760 bytes read in 209 ms (17 MiB/s)

Which loads the kernel image.

> reading initrd.img
> 2870030 bytes read in 178 ms (15.4 MiB/s)

The init ramdisk.

> reading /dtbs/am335x-boneblack.dtb
> 25080 bytes read in 12 ms (2 MiB/s)

And the Device Tree.

> Kernel image @ 0x82000000 [ 0x000000 - 0x38ba80 ]
> ## Flattened Device Tree blob at 88000000
>    Booting using the fdt blob at 0x88000000
>    Using Device Tree in place at 88000000, end 880091f7
> 
> Starting kernel ...

And boots the kernel.

Everything seems fine here.

> It seems obvious to me I should include a uEnv.txt on my images but I have
> no experience of how to write one (current buildroot has spoiled me, I
> know).
> 
> Am I correct in my assumptions?  Does anyone have a minimal uEnv.txt that
> works from me to start from?

You might want to look at http://patchwork.ozlabs.org/patch/330289/,
which is a patch that has been proposed, to improve a bit the Buildroot
documentation about the Beagle Bone Black. It contains a basic uEnv.txt
file which looks like this:

bootpart=0:1
bootdir=
uenvcmd=run loaduimage;run loadramdisk;run findfdt;run loadfdt;run ramboot 

Basically, all it does is load a kernel image, a ramdisk, a Device
Tree, and boots the kernel.

Your problem is in fact not really related to Buildroot, it's more a
U-Boot configuration issue.

Let us know if you managed to get your BBB to work. If not, do not
hesitate to get back to us and provide more details about what's not
working.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com


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