[U-Boot-Users] Device tree home

[U-Boot-Users] Device tree home

[Jerry Van Baren]

Kim Phillips wrote:
> 3. does a subsystem maintainer get leverage into changes made in the
> higher level components of Das U-Boot?  E.g., I'm still a firm
> believer that the device tree source should live in the bootloader ;)
> 
> Kim

Hi Kim,

Back to the fdt/of methodology (I started a new thread since it is kind 
of a new topic)... I have a hot project that I have not quite gotten to 
yet to integrate the fdt more tightly into u-boot rather than it being 
some magic wedged into bootm.

The ultimate goal (for me) is to have an option where the u-boot env 
gets stored in a fdt rather than the current env so that the fdt really 
is native to u-boot.  The goal would be that all the current env 
commands would Just Work[tm].

For compatibility with architectures that don't use the fdt (i.e. 
everything other than PPC :-), the current env would have to be 
supported and and mongrel system of both traditional env and fdt would 
need to be supported as well for backwards compatibility.

I've been seriously looking at David Gibson's libfdt library which looks 
a lot more straightforward than the kernel's implementation.  (I've 
CC:ed him on this email since I don't believe he is subscribed to the 
u-boot list.)  For more information, see:
<http://www.archivesat.com/Linux_on_PowerPC_Developers/thread2163413.htm>

I have not thought of any reason this won't work.  I have not started 
implementing it yet, but it is #1 in my job jar. (That would be more 
meaningful if there weren't 20 other things also at #1. :-/)

Best regards,
gvb

[U-Boot-Users] Device tree home

[Kim Phillips]

On Thu, 18 Jan 2007 13:59:52 -0500
Jerry Van Baren <gerald.vanbaren@smiths-aerospace.com> wrote:

> Kim Phillips wrote:
> > 3. does a subsystem maintainer get leverage into changes made in the
> > higher level components of Das U-Boot?  E.g., I'm still a firm
> > believer that the device tree source should live in the bootloader ;)
> > 
> > Kim
> 
> Hi Kim,
> 
> Back to the fdt/of methodology (I started a new thread since it is kind 
> of a new topic)... I have a hot project that I have not quite gotten to 
> yet to integrate the fdt more tightly into u-boot rather than it being 
> some magic wedged into bootm.
> 
> The ultimate goal (for me) is to have an option where the u-boot env 
> gets stored in a fdt rather than the current env so that the fdt really 
> is native to u-boot.  The goal would be that all the current env 
> commands would Just Work[tm].
> 
I'm not sure I understand the benefit of this - I thought the only parts of the device tree likely to get changed on the command line are the mac addresses and the chosen node's bootargs property, which today's u-boot handles well.

My belief is merely that the device tree data should belong in the u-boot image; they are both equally board specific.

Kim

[U-Boot-Users] Device tree home

[Timur Tabi]

Kim Phillips wrote:

> I'm not sure I understand the benefit of this - I thought the only parts of the device tree likely to get changed on the command line are the mac addresses and the chosen node's bootargs property, which today's u-boot handles well.

It also changes several properties: timebase-frequency, clock-frequency, and 
bus-frequency, although someone reported a possible bug in this code yesterday 
on linuxppc-embedded.

-- 
Timur Tabi
Linux Kernel Developer @ Freescale