Date: Sat, 01 Mar 2014 08:49:05 -0700 From: Ian Lepore <ian@FreeBSD.org> To: Tim Kientzle <tim@kientzle.com> Cc: freebsd-arm <freebsd-arm@FreeBSD.org> Subject: Re: A unified imx6 kernel config, old WANDBOARD-* configs going away Message-ID: <1393688945.1149.225.camel@revolution.hippie.lan> In-Reply-To: <F38D0A2F-D2AF-426D-8515-BD111501B2A2@kientzle.com> References: <1393594966.1149.161.camel@revolution.hippie.lan> <F38D0A2F-D2AF-426D-8515-BD111501B2A2@kientzle.com>
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On Sat, 2014-03-01 at 07:41 -0800, Tim Kientzle wrote:
> 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.
That's my long-term goal, but it'll take some major u-boot hacking,
probably won't happen for months. The imx6 quad chip is different
enough from the solo and dual-lite that a single u-boot to handle both
will be kind of tricky the way the u-boot code is structured now. Doing
a single u-boot for solo+dual-lite is so trivial I'm not sure why
wandboard didn't do it that way.
-- Ian
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