firmware/tools/replica

The printer replica

A container that runs the printer's own userland: the real rootfs.squashfs extracted from FlashForge's package, chrooted, with its MIPS binaries executing under qemu. uname -m says mips and busybox applets behave exactly as they do on the machine.

It lives under tools/ rather than test/ because it is not a test. Three different things drive it, and only one of them is a suite:

driver	what it does with it
bin/payload.sh -> bin/build-payload.py	the build path. The payload is assembled by running the PRINTER'S OWN opkg against /, inside here. Nothing on the host can do that
qa/lib/replica.py	the replica lane's printer fixture -- holds one container open and probes it
make boot-screen-sim	rendering the boot frames on the cross-built CPython

printer/                  the machine itself, SHELL on purpose: it is executed
                          by the printer's ash under qemu, and that it survives
                          that is a large part of what the suite proves
  Dockerfile              the container: qemu-user-static, rsync, openssl,
                          dosfstools. It contributes no userland worth speaking
                          of -- everything real comes from the chroot
  Dockerfile.full         the same, plus the firmware baked in: a prebuilt
                          PRINTER_IMAGE, so a run does not unpack 93MB
  binfmt.sh               registers a handler for the printer's binaries. The
                          stock qemu-mipsel registration does not match them:
                          its mask requires e_ident[EI_ABIVERSION] == 0 and
                          every binary the Ingenic toolchain built has 3 there
  assemble.sh             the mount layout -- read-only root, writable prog and
                          data partitions, optionally a real FAT USB stick
  seed-prog.sh            a /usr/prog that looks like a printer's
  entrypoint.sh           setup, then the case script it was given
  entrypoint-out.sh       the same, plus a writable /out inside the chroot
  bake.sh, bake-case.sh   install a package and commit the result as an image
ffsim/                    the host half. NOT a test framework -- it was one,
                          and 1,657 lines of it are gone; what is left starts
                          containers and reads config.env/test.env
build-printer-image.sh    bakes a prebuilt replica image (`make printer-image`)
sim-boot-screen.py        `make boot-screen-sim`

--privileged buys exactly two things: the binfmt registration, and the mount layout. Nothing here needs it for any other reason.

See docs/printer-replica.md for what the replica can and cannot prove, and docs/testing.md for the suites.