[yocto] Changing syslinux configuration

[Paul D. DeRocco]

For my system (something similar to core-image-base running on a Cedartrail
Atom mobo), the syslinux.cfg file needs to be tweaked. It is built by a
script in syslinux.bbclass, which is controlled by various variables. First
of all, it's important that it not try to use a serial port as a console, so
that means I'm supposed to set SYSLINUX_SERIAL to "". Second, it's providing
two choices called "boot" and "install", and I'd like to eliminate the
latter, which involves setting the LABELS variable to "boot".

I see that syslinux.bbclass has default value of "0 115200", but it has no
default value for LABELS, which would cause a failure if something else
wasn't setting it to "boot install". I see that it is inherited by
boot-directdisk.bbclass, but it doesn't provide a default value for LABELS,
either.

Does anyone know what recipe actually sets LABELS? And then, do I override
these variables by creating a .bbappend file for that recipe? Or are these
two symbols global symbols that I can somehow supply values for in my layer
file? I really have no understanding of the scope of all the multiplicity of
variables in the Bitbake system. Does each recipe have its own namespace for
variables, or is everything global?

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Ciao,               Paul D. DeRocco
Paul                mailto:pderocco at ix.netcom.com