A unified imx6 kernel config, old WANDBOARD-* configs going away

Tom Everett tom at khubla.com
Mon Mar 3 01:58:38 UTC 2014


I've got my wandboard quad booting now, with wandboard-quad.dtb in
/boot/kernel/.    I've submitted a patch to crochet-freebsd and the latest
build is up at my FTP.

Ian, your patch to ubldr appears to work perfectly.



On Sun, Mar 2, 2014 at 9:41 AM, Ian Lepore <ian at freebsd.org> wrote:

> On Sun, 2014-03-02 at 09:30 -0700, Warner Losh wrote:
> > On Mar 1, 2014, at 8:42 PM, Ian Lepore <ian at FreeBSD.org> wrote:
> >
> > > On Sat, 2014-03-01 at 18:01 -0700, Tom Everett wrote:
> > >> I'm looking at the crochet code, and I see in freebsd_install_fdt
> that both
> > >> *.dtb and *.dts are supported. However on the source tree it's
> imx6.dtsi.
> > >> What's the difference b/t a dts file and a dtsi file?
> > >
> > > A .dtsi file is an include file used by .dts files.  A .dtb is the
> > > binary (compiled) form used by the kernel.
> > >
> > > So there are several wandboard-something.dts files, each of which
> > > includes imx6.dtsi where all the common parts live.  For a new imx6
> > > device, a new board-named file similar to one of the wandboard files is
> > > necessary, and it would also include imx6.dtsi.
> >
> > As would other boards that use the imx6 SoC. They'd have their own .dts
> > file that included the imx6.dsti and customized it for how they are wired
> > together.
> >
> > > We're pushing hard towards just using the standard dtb files from
> > > vendors, but we've got a bit of work to do before we're there.
> >
> > I have some rough changes that allow us to build N different DTBs as part
> > of the kernel build, but not glom them into the kernel. Not strictly
> required
> > for this, but helpful.
> >
> > I'm planning on having Atmel use 100% vendor supplied files as well.
> > It is a very good goal. There's also efforts on the linux side to
> separate out
> > the device-trees from the linux kernel, which is where I grabbed the
> recent
> > /vendor/device-tree stuff from.
> >
> > Warner
>
> For imx6, the big obstacle to using vendor dtb files is now just the
> device instantiation order.  The stock dts files list devices basically
> in order of their memory-mapped register addresses, but we need the
> interrupt controller to be available first regardless of where it's
> mapped, and likewise for a few other critical devices.
>
> I need to do another round of experimentation with the
> EARLY_DRIVER_MODULE() stuff and multipass device instantiation.  We may
> not be all that far from success.
>
> -- Ian
>
>
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