[meta-xilinx] u-boot environment limit

[Nathan Rossi]

On 15 February 2017 at 00:39, Arno Steffens <star at gmx.li> wrote:
>> On 14 February 2017 at 23:22, Arno Steffens <star at gmx.li> wrote:
>> > If I increase the uboot environment (by patching zynq-common.h) it happens that uboot stops working.
>> > With a few lines changing/adding it seems to boot normal.
>> > With more lines is stops after "DRAM:  ECC disabled 496 MiB"
>> >
>> > Now I played with the patch and get once this (see below):
>> > This looks a bit like overwriting memory.
>> >
>> > So is there a fix limit for the environment? It seems to be one huge string, right?
>> > How can I extend this? Is this a bug?
>> >
>> > #define CONFIG_ENV_SIZE                 0x10000 -> this seems to me big enough.
>>
>> The default zynq-common.h CONFIG_ENV_SIZE is double this value, 128 <<
>> 10 == 0x20000. And the default environment is pretty packed (64K might
>> not be enough).
>>
>> If you want your environment to fit within 64K, you will need to
>> reduce the default environment config that is provided by
>> zynq-common.h.
>>
>
> Uboot shows me like that:
> Environment size: 4437/65532 bytes
> Seems to be much headroom
>
>> >
>> > U-Boot 2016.07-dirty (Feb 14 2017 - 12:59:07 +0100)
>> >
>> > Model: Zynq MicroZED Board
>> > Board: Xilinx Zynq
>> > DRAM:  ECC disabled 496 MiB
>> > Error binding driver 'gpio_zynq': -12
>> > Error binding driver 'serial_zynq': -12
>> > Error binding driver 'zynq_qspi': -12
>> > Error binding driver 'zynq_gem': -12
>> > Error binding driver 'arasan_sdhci': -12
>> > Error binding driver 'generic_simple_bus': -12
>> > Some drivers failed to bind
>> > Error binding driver 'generic_simple_bus': -12
>> > Some drivers failed to bind
>> > initcall sequence 1ef99b98 failed at call 0400ea34 (err=-12)
>> > ### ERROR ### Please RESET the board ###
>>
>> These are all ENOMEM errors, likely caused because they are trying to
>> read/write past the end of the environment.
>>
>
> Looking at this I can see an address simular to this one:
> fdtcontroladdr=1ef95d30

The 0x1ef99b98 is just a ptr to the function being executed in the
initcall array. Its just telling you it failed in the 'initf_dm'
(guessing since i don't have your binaries symbol table) function of
the sequence.

Without being able to debug your error it looks like the first case
that could cause those "error binding..." messages is here:

https://github.com/Xilinx/u-boot-xlnx/blob/xilinx-v2016.4/drivers/core/device.c#L51
(not sure the exact version of u-boot you are using)

> Does it mean to less RAM for uboot?
>
> I don't set this strange number active, found this is
>
> ./common/board_r.c:     setenv_addr("fdtcontroladdr", gd->fdt_blob);
>
> # ifndef CONFIG_SPL_BUILD
>         /* Allow the early environment to override the fdt address */
>         gd->fdt_blob = (void *)getenv_ulong("fdtcontroladdr", 16,
>                                                 (uintptr_t)gd->fdt_blob);
> # endif
>
> I have less memory than the standard 1GB.
> Just 512MB witch is splitted to 496 and 16 MB via devicetree:

512MB should be fine (zybo has 512MB). I've never tried 496MB though.
You could try with the full 512MB of memory and see if you hit the
same errors.

Also regarding your dts below, you will need to specify the full
memory size if using the "reserved-memory" feature of the linux
kernel, since it works by reserving available regions
(https://www.kernel.org/doc/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt).
Also this feature is not available in u-boot.

Regards,
Nathan

>
> -       memory {
> -               device_type = "memory";
> -               reg = <0 0x40000000>;
> -       };
> +  memory {
> +    device_type = "memory";
> +    reg = <0x0 0x1f000000>;
> +  };
> +
> +  reserved-memory {
> +    #address-cells = <1>;
> +    #size-cells = <1>;
> +    ranges;
> +    buffer_fpga: buffer_fpga at 0x1f000000 {
> +    no-map;
> +    reg = <0x1f000000 0x1000000>;
> +    };
> +  };
>
>
>
> Best regards
> Steffen
>
>
>
>
>> Regards,
>> Nathan
>>