[U-Boot] mlo and u-boot

[U-Boot] mlo and u-boot

[Ryan]

Hello,

I am using AM43XX based board. The bootloader is divided into spl
u-boot (MLO) and u-boot.bin

I wanted to check what variables are shared between them. How does MLO
a seperate binary
share the boot mode and mmcdev to u-boot so that it can use the
appropriate mmcdev to find the
kernel.

thanks,

[U-Boot] mlo and u-boot

[Lukasz Majewski]

On Wed, 22 Feb 2017 23:53:32 +0530
Ryan <ryanphilips19@googlemail.com> wrote:

> Hello,
> 
> I am using AM43XX based board. The bootloader is divided into spl
> u-boot (MLO) and u-boot.bin
> 
> I wanted to check what variables are shared between them. How does MLO
> a seperate binary
> share the boot mode and mmcdev to u-boot so that it can use the
> appropriate mmcdev to find the
> kernel.

In u-boot, there is the concept of "environment variables", which are
stored in a separate non-persistent memory (like eMMC, NAND,) or file
system.

For example BBB uses eMMC to store envs.

It is possible to read envs in MLO and u-boot.

> 
> thanks,
> _______________________________________________
> U-Boot mailing list
> U-Boot at lists.denx.de
> http://lists.denx.de/mailman/listinfo/u-boot


Best regards,

Lukasz Majewski

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HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de

[U-Boot] mlo and u-boot

[Andrew F. Davis]

On 02/22/2017 12:23 PM, Ryan wrote:
> Hello,
> 
> I am using AM43XX based board. The bootloader is divided into spl
> u-boot (MLO) and u-boot.bin
> 
> I wanted to check what variables are shared between them. How does MLO
> a seperate binary
> share the boot mode and mmcdev to u-boot so that it can use the
> appropriate mmcdev to find the
> kernel.
> 

These are passed using a shared SRAM space, grep for
SRAM_SCRATCH_SPACE_ADDR, and you can follow the rabbit hole from there.

Andrew

> thanks,
> _______________________________________________
> U-Boot mailing list
> U-Boot at lists.denx.de
> http://lists.denx.de/mailman/listinfo/u-boot
>