embedded a default dtb in the kernel (was merge dtc)

embedded a default dtb in the kernel (was merge dtc)

[Leisner, Martin]

Is there a way to embed a default dtb into the kernel?
When I build a kernel, I want to embed a dtb into it --
so I don't have to deal with the headaches of finding the
right file to match the right board (its always easier to
deal with 1 file than 2).

If there is, it makes sense to put dtc into the tree.
If there's not, there should be a way to embed dtb's; and put
dtc and dts's into the tree.
If there can't be (I haven't examined this but relaying my
experiences), then it should be in a separate repository
(but the DTS and DTC should be in one place).
It was a little difficult to cobble together a working=20
system the first time.

Also, mkimage SHOULD definitely go in the tree.  Its necessary
to build, hence should be in the tree...

There are cases where one kernel can support multiple boards/DTBs.
I guess boot flags can control whether to use an embedded DTB or
one passed from uboot...

marty

Re: embedded a default dtb in the kernel (was merge dtc)

[Grant Likely]

On 10/19/07, Leisner, Martin <Martin.Leisner@xerox.com> wrote:
> Is there a way to embed a default dtb into the kernel?
> When I build a kernel, I want to embed a dtb into it --
> so I don't have to deal with the headaches of finding the
> right file to match the right board (its always easier to
> deal with 1 file than 2).
>
> If there is, it makes sense to put dtc into the tree.
> If there's not, there should be a way to embed dtb's; and put
> dtc and dts's into the tree.
> If there can't be (I haven't examined this but relaying my
> experiences), then it should be in a separate repository
> (but the DTS and DTC should be in one place).
> It was a little difficult to cobble together a working
> system the first time.
>
> Also, mkimage SHOULD definitely go in the tree.  Its necessary
> to build, hence should be in the tree...

Why?  mkimage is u-boot specific, and hence is maintained by u-boot.
If you're not using u-boot, then you don't need mkimage.  What is
wrong with it being a prereq like all the other tools we use?  If
you're doing embedded development, you're installing non-distribution
cross toolchain anyway.

dtc and mkimage are embedded development tools.  They belong with the
embedded development toolchain.  mkimage is already part of ELDK.

Cheers,
g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
grant.likely@secretlab.ca
(403) 399-0195

Re: embedded a default dtb in the kernel (was merge dtc)

[David Gibson]

On Fri, Oct 19, 2007 at 01:09:39PM -0600, Grant Likely wrote:
> On 10/19/07, Leisner, Martin <Martin.Leisner@xerox.com> wrote:
> > Is there a way to embed a default dtb into the kernel?
> > When I build a kernel, I want to embed a dtb into it --
> > so I don't have to deal with the headaches of finding the
> > right file to match the right board (its always easier to
> > deal with 1 file than 2).
> >
> > If there is, it makes sense to put dtc into the tree.
> > If there's not, there should be a way to embed dtb's; and put
> > dtc and dts's into the tree.
> > If there can't be (I haven't examined this but relaying my
> > experiences), then it should be in a separate repository
> > (but the DTS and DTC should be in one place).
> > It was a little difficult to cobble together a working
> > system the first time.
> >
> > Also, mkimage SHOULD definitely go in the tree.  Its necessary
> > to build, hence should be in the tree...
> 
> Why?  mkimage is u-boot specific, and hence is maintained by u-boot.
> If you're not using u-boot, then you don't need mkimage.  What is
> wrong with it being a prereq like all the other tools we use?  If
> you're doing embedded development, you're installing non-distribution
> cross toolchain anyway.

The problem is that we build uImages at present, without option, for a
bunch of targets that don't necessarily have u-boot.

> dtc and mkimage are embedded development tools.  They belong with the
> embedded development toolchain.  mkimage is already part of ELDK.

dtc isn't just for embedded.  ps3 uses it already, and more may well
do so in future.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

Re: embedded a default dtb in the kernel (was merge dtc)

[David Gibson]

On Fri, Oct 19, 2007 at 02:30:28PM -0400, Leisner, Martin wrote:
> Is there a way to embed a default dtb into the kernel?
> When I build a kernel, I want to embed a dtb into it --
> so I don't have to deal with the headaches of finding the
> right file to match the right board (its always easier to
> deal with 1 file than 2).

You can't embed a dtb in the vmlinux, but zImages routinely contain an
embedded dtb.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson