Files are not installed from recipe - image

Question

I'm trying to create a custom recipe to sign a u-boot image generated from u-boot.bb.
I have 2 custom recipes:
1. u-boot.bb - clones, compiles and deploys u-boot resulting u-boot.elf.
2. u-boot-sign.bb - depends on u-boot.bb. Gets u-boot.elf, passes it through
custom signing procedure and deploys the result.
For signing I am forced to use a custom procedure which is in a form of python scripts located in external repository.
The part which causes a problem is accessing a deployed u-boot.elf binary file from u-boot.bb recipe. I cannot find a way to expose u-boot.elf binary file to a u-boot-sign.bb recipe.
What should be the correct way of exposing an image binary file from one recipe, to be accessed, signed and deployed in another recipe?

Answer 1

For the purpose of sharing the files between recipes and between cross-compilation scope, I used ${datadir} when installing the binaries (via do_install). This allowed me to access all files described by FILES:${PN} via recipe-sysroot.
u-boot.bb - exporting recipe:
…
do_install() {
install -d ${D}${datadir}/u-boot-2016/
install -m 0644 ${B}/${UBOOT_ELF_BINARY} ${D}${datadir}/u-boot-2016
}
FILES:${PN} = "${datadir}/u-boot-2016"
…
u-boot-sign.bb - depending recipe
…
DEPENDS += " u-boot python3-native"
do_sign() {
${STAGING_BINDIR_NATIVE}/python3-native/python3 sign.py \
-i ${RECIPE_SYSROOT}${datadir}/u-boot-2016/${UBOOT_ELF_BINARY}
}
…
Inspiration from Here
Edit
I was advised not to transfer files like this using ${datadir}. For intermediate files the better approach would be to use to use /firmware as it is done in meta-arm.
u-boot.bb - exporting recipe:
…
do_install() {
install -D -p -m 0644 ${B}/${UBOOT_ELF_BINARY} ${D}/firmware/${UBOOT_ELF_BINARY}
}
FILES:${PN} = "/firmware"
SYSROOT_DIRS += "/firmware"
…
u-boot-sign.bb - depending recipe
…
DEPENDS += " u-boot python3-native"
do_sign() {
${STAGING_BINDIR_NATIVE}/python3-native/python3 sign.py \
-i ${RECIPE_SYSROOT}/firmware/u-boot-2016/${UBOOT_ELF_BINARY}
}
…
It also requires to add /firmware to SYSROOT_DIRS.