PowerPC/e500: how is FDT access supposed to work?

[Chris Johns]

On 7/7/2024 6:41 pm, Daniel Wohllebe wrote:
> Hello Sebastian,
> 
> thank you for your response. I found out that the problem was me including the
> FDT-address incorrectly in the boot-command.
> 
> For anybody who may also stumble upon this future, I will give a small outline
> of what to check for:

Thank you for the feedback. Would updating the User manual help?

Chris

> 
> On the U-Boot commandline, we can see the environment via printenv...
> 
> ```
> => printenv
> bootcmd=test -n "$qemu_kernel_addr" && bootm $qemu_kernel_addr - $fdtcontroladdr
> ethaddr=52:52:52:52:52:52
> fdtcontroladdr=7a6de90
> stderr=serial at 4500
> stdin=serial at 4500
> stdout=serial at 4500
> ```
> 
> We can see the env-variable holding the address of the FDT, $fdtcontroladdr.
> I used the bootm command to boot but did so with the wrong arguments.  What I
> need to use to boot (with my application loaded to 0x2000000) is...
> 
> ```
> => bootm 0x2000000 - $fdtcontroladdr
> ## Booting kernel from Legacy Image at 02000000 ...
>    Image Name:   RTEMS
>    Created:      2024-06-26   9:32:37 UTC
>    Image Type:   PowerPC Linux Kernel Image (gzip compressed)
>    Data Size:    2279513 Bytes = 2.2 MiB
>    Load Address: 00004000
>    Entry Point:  00004000
>    Verifying Checksum ... OK
> 
> ## Flattened Device Tree blob at 07a6de90
>    Booting using the fdt blob at 0x7a6de90
>    Uncompressing Kernel Image
>    Loading Device Tree to 03efc000, end 03ffefff ... OK
> ```
> 
> 
> Kind Regards,
> 
> Daniel Wohllebe
> 
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