BUP image and UEFI Capsule generation questions

[igoropaniuk]

I've been learning recently about how BUP/UEFI capsules are generated in the latest master.
Correct my if I'm wrong:

BUP creation logic is implemented in classes/image_types_tegra.bbclass, in create_bup_payload_image():

775 create_bup_payload_image() {                                                    
776     local type="$1"                                                             
777     oe_make_bup_payload ${IMGDEPLOYDIR}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.${type}
778     for f in ${WORKDIR}/bup-payload/*_only_payload; do                          
779         [ -e $f ] || continue                                                   
780         sfx=$(basename $f _payload)                                             
781         install -m 0644 $f ${IMGDEPLOYDIR}/${IMAGE_NAME}.$sfx.bup-payload       
782         ln -sf ${IMAGE_NAME}.$sfx.bup-payload ${IMGDEPLOYDIR}/${IMAGE_LINK_NAME}.$sfx.bup-payload
783     done                                                                        
784 }      

This function is defined in CONVERSION_CMD for bup-payload image type CONVERSION_CMD:bup-payload = "create_bup_payload_image ${type}", which implies that we should have some image with bup-payload type defined in INITRAMFS_FSTYPES.

Final UEFI capsule is generated by tegra-uefi-capsule recipe, which expects BUP blobs to be deployed to $DEPLOY_DIR_IMAGE in advance.

Was there any particular reason why BUP creation is done via CONVERSION_CMD and not in a dedicated recipe (like it's currently done for UEFI capsule generation integra-uefi-capsule recipe)? is there any some sort of update process which requires a running initrd?

[madisongh]

There's some history to the way this is structured that pre-dates UEFI and capsules. There's also some history to the assumption that the kernel uses a initrd. Going forward, I'd like to get rid of the separate BUP generation and move that into the capsule creation recipes.

If you're having problems building/using a kernel without an initrd because a kernel BUP never gets generated, that should probably be fixable in the kernel-bup-payload recipe, which is the non-CONVERSION_CMD way to generate a kernel BUP. The logic in there now looks like only works for bundled initramfs images, not for plain kernels with no initrd/initramfs at all.