[yocto] How Does Yocto Fill In UBOOT_MACHINE?

[Leo Schwab]

On Thu, Aug 15, 2013 at 1:21 PM, Leo Schwab <lschwab at sensity.com> wrote:
> Still not entirely clear why the results differ.
>
I still haven't figured out why those two runs are different, but I
think I see what I might have done wrong with the .bbappend file.  Put
briefly: I copy-pasted Freescale's work.

Again, my u-boot-imx_2009.08.bbappend file:

----
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"

SRC_URI_append_ourboard = "file://u-boot-ourboard.patch"

UBOOT_MACHINE_ourboard = "mx6_ourboard_config"
----

The reason I put a UBOOT_MACHINE_ourboard assignment in there at all
is because Freescale does something similar in their
meta-fsl-arm/recipes-bsp/u-boot/u-boot-imx_2009.08.bb file for all
their development boards:

----
[ ...blah, blah, blah... ]
UBOOT_MACHINE_imx53qsb = "mx53_loco_config"
UBOOT_MACHINE_imx53ard = "mx53_ard_ddr3_config"
UBOOT_MACHINE_imx51evk = "mx51_bbg_config"
UBOOT_MACHINE_imx6qsabrelite = "mx6q_sabrelite_config"
UBOOT_MACHINE_imx6qsabreauto = "mx6q_sabreauto_config"
UBOOT_MACHINE_imx6qsabresd = "mx6q_sabresd_config"
UBOOT_MACHINE_imx6dlsabresd = "mx6dl_sabresd_config"
UBOOT_MACHINE_imx6slevk = "mx6sl_evk_config"
UBOOT_MACHINE_imx28evk = "mx28_evk_config"
[ ... ]
----

Near as I can tell, however, these override assignments are redundant,
as they have machine definitions located at
meta-fsl-arm/conf/machine/*.conf, each of which assigns a value to
UBOOT_MACHINE.  Indeed, if I'm reading the bitbake docs correctly, the
above assignments will override any UBOOT_MACHINE assignment in any
other machine/*.conf file (this potential gotcha is currently obscured
by the fact that the same value is assigned in both places).

>From this, I conclude that I should remove the UBOOT_MACHINE_ourboard
assignment from my .bbappend file entirely, since the OVERRIDES
facility doesn't really buy me anything in this instance, and
(manifestly) leads to confusion.  Does that seem reasonable?

Schwab