Cannot build imx-boot on scarthgap branch

[jadinm]

compile_mx93 & do_compile define the same global (i.e., persistent through the do_compile task) variables:

• UBOOT_CONFIG_EXTRA
• BOOT_CONFIG_MACHINE_EXTRA

These functions unset this global variables at the end of their respective block, essentially emptying the value of the variable.

The problem is that do_compile calls the other one and still attempts to read BOOT_CONFIG_MACHINE_EXTRA afterwards

compile_${SOC_FAMILY} # transformed to a call to compile_mx93 or compile_mx8ulp
# [...]
if [ -e "${BOOT_STAGING}/flash.bin" ]; then
    cp ${BOOT_STAGING}/flash.bin ${S}/${BOOT_CONFIG_MACHINE_EXTRA}-${target}
fi

(see https://github.com/Avnet/meta-maaxboard/blob/scarthgap/recipes-bsp/imx-mkimage/imx-boot_1.0.bbappend)

This code will create a "-${target}" file that won't be found during the do_deploy task and the image won't build.

Since these function set the variables to the same values, the easiest fix is to make all that initialization into do_compile and never change or unset those global variables in any other "sub-function".

If you wish to temporarily shadow a variable, then use function-local variables (just prefix the name by local).
Though, bash is a bit special compared to other languages since a "function-local" variable are accessible to any function called.