meta-fsl-ppc: question on the use of appending MACHINEOVERRIDES instead of prepending...

[Bob Cochran <yocto@mindchasers.com>]

Hi,

It's fairly common to see the use of file overrides in meta-fsl-ppc 
bbappend files so a customized conf file can get picked up during a 
build.  In the paths below, qoriq-ppc is a MACHINEOVERRIDE:

./recipes-core/init-ifupdown/init-ifupdown/qoriq-ppc
./recipes-core/udev/udev-extraconf/qoriq-ppc
./virtualization-layer/recipes-extended/libvirt/libvirt/qoriq-ppc


FILESPATH is built using FILESOVERRIDES, and FILESOVERIDES is 
constructed as follows:

"${TRANSLATED_TARGET_ARCH}:${MACHINEOVERRIDES}:${DISTROOVERRIDES}"

Overrides are applied from right to left when constructing FILESPATH; 
therefore, overrides to the right have higher precedence.

In various meta-fsl-ppc conf/*.inc files, MACHINEOVERRIDES are added 
using appends, which sets the override to the right of the MACHINE being 
built, which was set in local.conf.

In my case (where t1040rdb-64b is my MACHINE):

FILESOVERRIDES="powerpc64:t1:t1040:t1040rdb-64b:qoriq-ppc:e5500-64b:poky"		


Therefore, if I put a file under 
./recipes-core/init-ifupdown/init-ifupdown/t1040rdb-64b, it will be 
searched after ./recipes-core/init-ifupdown/init-ifupdown/qoriq-ppc or 
not at all.

Also, a file under e5500-64b will be found before the same file under 
qoriq-ppc.

I don't think this is what we want, since a less specific folder is 
being picked up before a more specific folder.

Please let me know if I'm wrong about something here.  If not, can we 
make a change?

Thanks,

Bob