The Python scripts that OP-TEE 4.6.0's core build runs, in Crystal, so OP-TEE builds in the BQ2 seed without Python. Each subcommand is one script, and takes the same arguments:

Subcommand	Replaces	Makes
arm32_sysreg	scripts/arm32_sysreg.py	ARMv7 system-register accessors (C or assembler)
pem_to_pub_c	scripts/pem_to_pub_c.py	the TA signing key's modulus and exponent as C
gen_ldelf_hex	scripts/gen_ldelf_hex.py	ldelf's load segments as a C array
gen_ld_sects	scripts/gen_ld_sects.py	linker-script input sections from readelf -S -W
gen_tee_bin	scripts/gen_tee_bin.py	tee.bin, tee-raw.bin, and the v2 tee-header, tee-pager and tee-pageable images

bsp/beagley-ai/patches/optee_os/0001-build-run-the-core-build-helpers-with-cleave-optee.patch makes OP-TEE call $(CLEAVE_OPTEE) <name> where it called $(PYTHON3) scripts/<name>.py. The default is CLEAVE_OPTEE ?= cleave-optee. The scripts for early TAs, secure partitions, embedded DTBs and mem_usage are untouched, because the BeagleY-AI build uses none of them.

ELF files are read by src/cleave/elf.cr, little-endian ELF32 and ELF64.

Checked

• Fixtures. spec/optee_spec.cr compares every subcommand with the real scripts' output. It uses a tiny AArch64 ELF (tiny.S) for gen_tee_bin and gen_ldelf_hex.
• The k3-am62x build. On a full PLATFORM=k3-am62x CFG_ARM64_core=y COMPILER=clang build of 4.6.0, all 15 generated files are identical to the Python ones: the five boot images, ldelf_hex.c, ta_pub_key.c, the four arm32_*sysreg.{h,S}, and the four *.ld.S.
• No Python. The patched tree builds with PYTHON3=/bin/false. The images then differ from the earlier build only in the 5 bytes of OP-TEE's build timestamp.