Date: Sat, 1 Mar 2014 07:41:01 -0800 From: Tim Kientzle <tim@kientzle.com> To: Ian Lepore <ian@freebsd.org> Cc: freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: A unified imx6 kernel config, old WANDBOARD-* configs going away Message-ID: <F38D0A2F-D2AF-426D-8515-BD111501B2A2@kientzle.com> In-Reply-To: <1393594966.1149.161.camel@revolution.hippie.lan>
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On Feb 28, 2014, at 5:42 AM, Ian Lepore <ian@freebsd.org> wrote:
> I've added a new imx6 unified kernel config named IMX6. It has no
> compiled-in fdt, and can boot all three flavors of Wandboard when u-boot
> and ubldr load a dtb file. Folks should start using it and eventually
> the WANDBOARD* configs will go away when nobody needs them anymore.
Nice! Another step towards GENERIC ARM.
> the .dtb file in your /boot/kernel or /boot/modules directory, and ubldr
> will load it from there, using the filename set in the u-boot env var
> fdt_file.
Using a U-Boot env var to specify the FDT is a nice idea.
> Unfortunately we can't do a single image that boots any wandboard,
> because u-boot itself has to be different for each board. This is what
> my u-boot env looks like on each wandboard:
>
> => printenv
> baudrate=115200
> bootcmd=run ubnet
> bootdelay=1
> console=ttymxc0
> fdt_file=wandboard-dual.dtb
> loadaddr=11000000
> loaderdev=net
> ubmmc=fatload mmc 0 ${loadaddr} ubldr; bootelf
> ubnet=dhcp ${loadaddr} /wand/boot/ubldr;bootelf
>
> Environment size: 265/8188 bytes
>
> The only thing that differs per-board is the fdt_file setting, and the
> u-boot binary itself.
If you could get to a single U-Boot binary, you might
be able to do what BeagleBone does: The U-boot.env
script detects the board variation and conditionally
loads the correct DTB blob.
Tim
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