Hi Jerry and Wolfgang,
Thanks for your suggestions.
ciao ciao
luigi
venerdì 23 ottobre 2009 13:39 Jerry Van Baren gerald.vanbaren@ge.com ha scritto: Luigi 'Comio' Mantellini wrote:
Hi Ml,
I'm working on a ppc8541 based board. I ported the U-boot board just
creationg
a "strip-down" version of frescale8541 board (I don't use TSEC and Quicc, ...)- My next task is to have the first boot with linux and I'm a lot confused by
fdt
usage.
In the past I always worked on mips based SoC and the ppc is a new world for me, then my apologies for my stupid questions.
s/ppc/powerpc/ - the linux ppc arch doesn't support fdt. ;-)
I have a couple of (trivial) question/doubts regarding the fdt usage:
- I created my dts/dtb (exentially copying a 8541 board): How can this
object
be used by u-boot? should I copy it into the flash (for example)?
Strictly speaking, it isn't *used* by u-boot, but it is manipulated by u-boot to fix it up / augment it to describe the board's hardware. It is then *used* by linux - it allows one linux image to boot on a wide variety of boards (MAJOR win).
You need to pass a fdt blob to the linux kernel. As always, there are many ways to do this. One way is to program it into flash. This is great if your blob is stable (e.g. good for manufacturing). Another way is to tftp the blob over from your server along with your linux image.
The *slickest* way by far is to use a FIT image - this wraps *everything* (kernel, board fdt blob, ramdisk) in a fdt blob. See u-boot/doc/uimage.FIT
- is there a how-to or a survey regarding the fdt usage into u-boot (and
linux kernel)?
There are various fdt whitepapers out there and *how* the fdt is used by linux is documented in the linux source tree. For PowerPC processors: linux/Documentation/powerpc
thanks for help,
luigi
Best regards, gvb