[Buildroot] [At91Bootstrap3] Overriding dtb chosen arguments for kernel command line
Thomas Petazzoni
thomas.petazzoni at bootlin.com
Fri Mar 23 20:17:35 UTC 2018
Hello,
On Fri, 23 Mar 2018 16:15:32 -0300, Alejandro Ariel Fachini wrote:
> I have been using at91bootstrap3 to directly load kernel, using dtb on
> sam9x35ek, this kernel is mounting UBI RFS file.
> Wel i need to mount another file JFFS2 and i want to change parameters in
> Kernel Command Line.
> I treid from inside at91bootstrap3-v3.8.6 terminal using make menuconfig
> and selecting override kernel comand line but got error.
> Also tried manually changing arguments in linux menu config and still get
> the arguments inside DTB.
> How can i do this? Thank you very much.
> Note: I am not using U-Boot, using U-Boot is working ok.
Do you have CONFIG_ARM_ATAG_DTB_COMPAT enabled in your kernel
configuration ?
I suppose when you boot with U-Boot, U-Boot patches the DTB before
passing it to the kernel.
However, I don't think at91bootstrap3 patches the DTB, it probably just
passes an old style ATAGS, which the kernel will only pick up if
CONFIG_ARM_ATAG_DTB_COMPAT=y.
Note: this is just an hypothesis, I haven't actually checked the
at91bootstrap3 code.
Best regards,
Thomas Petazzoni
--
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com
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