The temporary page buffer is write-once per word, so a page filled over one an earlier writer left dirty programs the stale words. The same datasheet clause carries the cure: the buffer auto-erases after a page write (§26.2.1; §19.2 on the tinies), so the corruption clears itself by happening, and rewriting the page programs correctly. The loader therefore clears the buffer nowhere. The tinies' CTPB and the m48s' RWWSRE discard are gone; the boot-sectioned megas keep only the trailing RWWSRE they need anyway to re-enable the RWW section for read-back, which discards the buffer as a side effect and keeps them off the path entirely. 434 B on the tiny13s, 438-442 on the tiny25/45/85, 430 on the m48s; the megas are unchanged, the 1284s still 506. The host takes over the guarantee: a flash page that reads back wrong is rewritten up to RETRIES times before the run stops. Both read-back paths repair — verify_pages for programming, and write_differing, which is the loader-update path where a page left wrong is a half-written loader slot. That one is not hypothetical: deleting the discard made attiny85 pureboot.rehome fail deterministically there, the only flow still assuming the old contract. Protocol-visible, so README's W command says it: one W may program the wrong bytes after a refused page, or after an application that self-programmed entered without a reset, and a host that programs without reading back cannot trust it. Tests: pureboot.dirty drives the case the loader declines to guard — the fixture application dirties every buffer word and jumps in with no reset (hardware forbids that on a boot-sectioned mega, but simavr dispatches SPM from anywhere, which is what makes it constructible) — and asserts a bare verify sees the corruption, the repairing verify fixes it in one rewrite, and it stays fixed. pbreloc asserts the same shape after a refusal. test_planner covers the bound against a fake device: one bad write repaired in a single rewrite, a page that never comes good stopping after exactly three. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
258 lines
13 KiB
Python
258 lines
13 KiB
Python
#!/usr/bin/env python3
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"""Host-tool unit tests — the pure planning and policy logic, no simulator:
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the flash-programming orders and their recovery properties, the reset-vector
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surgery, the staging-slot composition, the mega boot-fuse decode, and the
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update preflight's error/warning matrix (fuse combinations simavr cannot
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model reach it here as synthetic bytes).
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Usage: test_planner.py <tool_py>
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"""
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import sys
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def fail(message):
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print(f"FAIL: {message}")
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sys.exit(1)
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def expect_error(what, fn, *needles):
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try:
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fn()
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except Exception as error:
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for needle in needles:
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if needle not in str(error):
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fail(f"{what}: error lacks {needle!r}: {error}")
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return
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fail(f"{what}: no error raised")
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def info_of(pb, base, page, patch, flash, signature=(0x1E, 0x93, 0x0B), word_flash=False):
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scale = 2 if word_flash else 1
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wire_base = base // scale
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flags = (1 if patch else 0) | (2 if word_flash else 0)
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raw = bytes((0x50, 0x42, 1, *signature, page & 0xFF, wire_base & 0xFF, wire_base >> 8,
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0, 2, flags))
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info = pb.Info(raw)
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assert info.flash_size == flash
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return info
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def rjmp_decode(word, at, flash_words):
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if word & 0xF000 != 0xC000:
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fail(f"not an rjmp: {word:#06x}")
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offset = word & 0x0FFF
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if offset >= 0x800:
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offset -= 0x1000
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return (at + 1 + offset) % flash_words
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def main():
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import os
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sys.path.insert(0, os.path.dirname(os.path.abspath(sys.argv[1])))
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import pureboot as pb
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tiny = info_of(pb, 0x1E00, 64, True, 0x2000)
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mega = info_of(pb, 0x7E00, 128, False, 0x8000, signature=(0x1E, 0x95, 0x0F))
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# mega_boot: BOOTSZ words and the BOOTRST sense per chip — the fuse byte
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# index (EXTENDED on the x8 line except the m328s' HIGH, HIGH elsewhere)
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# and the per-family ladders (Atmel-2486/2466/2503/2545/8271/DS40002065/
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# 8272/8011/2593/42719). Synthetic 'F' replies: only the boot byte
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# carries meaning.
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cases = (
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((0x1E, 0x93, 0x07), 0x2000, 3, {0b11: 0x1F00, 0b10: 0x1E00, 0b01: 0x1C00, 0b00: 0x1800}), # m8
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((0x1E, 0x94, 0x03), 0x4000, 3, {0b11: 0x3F00, 0b10: 0x3E00, 0b01: 0x3C00, 0b00: 0x3800}), # m16
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((0x1E, 0x95, 0x02), 0x8000, 3, {0b11: 0x7E00, 0b10: 0x7C00, 0b01: 0x7800, 0b00: 0x7000}), # m32
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((0x1E, 0x93, 0x0A), 0x2000, 2, {0b11: 0x1F00, 0b10: 0x1E00, 0b01: 0x1C00, 0b00: 0x1800}), # m88
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((0x1E, 0x93, 0x0F), 0x2000, 2, {0b11: 0x1F00, 0b10: 0x1E00, 0b01: 0x1C00, 0b00: 0x1800}), # m88P
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((0x1E, 0x94, 0x06), 0x4000, 2, {0b11: 0x3F00, 0b10: 0x3E00, 0b01: 0x3C00, 0b00: 0x3800}), # m168/168A
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((0x1E, 0x94, 0x0B), 0x4000, 2, {0b11: 0x3F00, 0b10: 0x3E00, 0b01: 0x3C00, 0b00: 0x3800}), # m168P
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((0x1E, 0x95, 0x14), 0x8000, 3, {0b11: 0x7E00, 0b10: 0x7C00, 0b01: 0x7800, 0b00: 0x7000}), # m328
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((0x1E, 0x95, 0x0F), 0x8000, 3, {0b11: 0x7E00, 0b10: 0x7C00, 0b01: 0x7800, 0b00: 0x7000}), # m328P
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((0x1E, 0x94, 0x0F), 0x4000, 3, {0b11: 0x3F00, 0b10: 0x3E00, 0b01: 0x3C00, 0b00: 0x3800}), # m164A
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((0x1E, 0x94, 0x0A), 0x4000, 3, {0b11: 0x3F00, 0b10: 0x3E00, 0b01: 0x3C00, 0b00: 0x3800}), # m164P
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((0x1E, 0x95, 0x15), 0x8000, 3, {0b11: 0x7E00, 0b10: 0x7C00, 0b01: 0x7800, 0b00: 0x7000}), # m324A
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((0x1E, 0x96, 0x09), 0x10000, 3, {0b11: 0xFC00, 0b10: 0xF800, 0b01: 0xF000, 0b00: 0xE000}), # m644
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((0x1E, 0x96, 0x0A), 0x10000, 3, {0b11: 0xFC00, 0b10: 0xF800, 0b01: 0xF000, 0b00: 0xE000}), # m644P
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((0x1E, 0x97, 0x06), 0x20000, 3, {0b11: 0x1FC00, 0b10: 0x1F800, 0b01: 0x1F000, 0b00: 0x1E000}), # 1284
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((0x1E, 0x97, 0x05), 0x20000, 3, {0b11: 0x1FC00, 0b10: 0x1F800, 0b01: 0x1F000, 0b00: 0x1E000}), # 1284P
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)
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for signature, flash, which, ladder in cases:
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# Word-addressed chips carry the 1 KiB slot (their smallest boot sector).
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slot = 1024 if flash > 0x10000 else 512
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chip = info_of(pb, flash - slot, 128 if flash < 0x20000 else 0, False, flash,
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signature=signature, word_flash=flash > 0x10000)
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for bits, start in ladder.items():
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fuses = bytearray((0xFF, 0xFF, 0xFF, 0xFF))
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fuses[which] = (0xF8 | (bits << 1)) & ~1
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prog, at = pb.mega_boot(chip, bytes(fuses))
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if not prog or at != start:
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fail(f"mega_boot {signature[1]:02x}{signature[2]:02x} BOOTSZ={bits:02b} programmed: {prog} {at:#07x}")
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fuses[which] |= 1
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prog, at = pb.mega_boot(chip, bytes(fuses))
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if prog or at != start:
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fail(f"mega_boot {signature[1]:02x}{signature[2]:02b} unprogrammed: {prog} {at:#07x}")
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# Word-addressed info decode: the 1284P's base/page ride the wire scaled,
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# and its slot is 1 KiB.
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big = info_of(pb, 0x1FC00, 0, False, 0x20000, signature=(0x1E, 0x97, 0x05), word_flash=True)
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if big.page != 256 or big.base != 0x1FC00 or big.stage != 0x1F800 or big.slot != 1024:
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fail(f"word-addressed info decode: page {big.page}, base {big.base:#x}, stage {big.stage:#x}")
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# Surgery: word 0 lands on the loader, the trampoline on the original
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# entry — checked with an independent decoder.
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app = bytes((0xC0 | 0x00, 0xC0)) + bytes((0x12,)) * 300 # rjmp .+0x00C0... entry word 0xC0C0
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entry = rjmp_decode(app[0] | (app[1] << 8), 0, tiny.flash_size // 2)
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pages = pb.plan_flash(app, tiny)
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word0 = pages[0][0] | (pages[0][1] << 8)
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if rjmp_decode(word0, 0, tiny.flash_size // 2) != tiny.base // 2:
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fail("surgery: patched word 0 misses the loader")
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tp = pages[tiny.base - 64]
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tramp = tp[62] | (tp[63] << 8)
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if rjmp_decode(tramp, (tiny.base - 2) // 2, tiny.flash_size // 2) != entry:
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fail("surgery: trampoline misses the original entry")
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expect_error("non-rjmp vector", lambda: pb.plan_flash(bytes((0x0C, 0x94)) + app[2:], tiny), "not an rjmp")
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looped = bytearray(app)
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word = pb.rjmp_to(0, tiny.base // 2, tiny.flash_size // 2)
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looped[0], looped[1] = word & 0xFF, word >> 8
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expect_error("read-back image", lambda: pb.plan_flash(bytes(looped), tiny), "read-back")
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expect_error("oversize image", lambda: pb.plan_flash(bytes(0x1DFF), tiny), "application flash ends")
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# Ordering: patched vector puts page 0 first and the trampoline second;
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# a boot section puts page 0 last. Blank pages drop only when erased.
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order = pb.covered(pages, tiny, skip_blank=False)
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if order[0] != 0 or order[1] != tiny.base - 64:
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fail(f"tiny order starts {order[:2]}, want page 0 then trampoline page")
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if sorted(order[2:]) != order[2:]:
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fail("tiny order tail not ascending")
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mega_pages = pb.plan_flash(bytes((0xFF,)) * 600, mega)
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morder = pb.covered(mega_pages, mega, skip_blank=False)
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if morder[-1] != 0 or sorted(morder[:-1]) != morder[:-1]:
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fail(f"mega order {morder}, want ascending with page 0 last")
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blanky = {0: pages[0], 64: bytes((0xFF,)) * 64, 128: pages[128], tiny.base - 64: tp}
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slim = pb.covered(blanky, tiny, skip_blank=True)
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if 64 in slim or 0 not in slim or tiny.base - 64 not in slim:
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fail(f"skip_blank order wrong: {slim}")
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# Staging content: the identical image plus the through-word on a
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# patched-vector chip; hard size clamps either way.
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image = bytes(range(256)) * 2 # 512 B — too big for a tiny slot
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expect_error("tiny staging size", lambda: pb.staging_content(image, tiny), "510")
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staged = pb.staging_content(image[:508], tiny)
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through = staged[510] | (staged[511] << 8)
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if rjmp_decode(through, (tiny.base - 2) // 2, tiny.flash_size // 2) != tiny.base // 2:
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fail("through-word misses the resident base")
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if pb.staging_content(image, mega) != image:
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fail("mega staging content should be the bare image")
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expect_error("mega staging size", lambda: pb.staging_content(image + b"!", mega), "512")
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# The embedded info block: found in a synthetic binary, absent in noise.
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binary = bytes((0xAA,)) * 10 + tiny.raw + bytes((0xBB,)) * 10
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found = pb.image_info(binary)
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if found is None or found.raw != tiny.raw:
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fail("image_info misses the embedded block")
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if pb.image_info(bytes((0xAA,)) * 40) is not None:
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fail("image_info invents a block")
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# loader_image must peel a padded image down to the slot content: a raw
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# .bin padded from address 0 (or a whole-flash read-back with the loader
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# resident at base) yields the same bytes as the bare slot image.
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import tempfile
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slot_image = bytes((0xAA,)) * 10 + tiny.raw + bytes((0xCC,)) * 40
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padded = bytes((0xFF,)) * tiny.base + slot_image
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with tempfile.NamedTemporaryFile(suffix=".bin", delete=False) as f:
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f.write(padded)
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padded_path = f.name
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try:
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if pb.loader_image(padded_path) != slot_image:
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fail("loader_image does not peel a padded image to the slot content")
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finally:
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os.unlink(padded_path)
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# Update preflight: the full fuse matrix, plus target mismatch.
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other = info_of(pb, 0x1E00, 32, True, 0x2000)
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expect_error("wrong-target image", lambda: pb.update_preflight(binary, other, None), "another target")
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expect_error("mega needs fuses", lambda: pb.update_preflight(bytes((0xAA,)) * 8 + mega.raw, mega, None),
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"--assume-fuses")
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mega_image = bytes((0xAA,)) * 8 + mega.raw
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def fuses(high):
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return bytes((0xFF, 0xFF, 0xFF, high))
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expect_error("BOOTSZ 512 B", lambda: pb.update_preflight(mega_image, mega, fuses(0xFE)),
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"cannot self-update", "BOOTSZ")
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notes = pb.update_preflight(mega_image, mega, fuses(0xFD)) # 1 KB, BOOTRST unprogrammed
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if not any("BOOTRST unprogrammed" in n for n in notes):
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fail(f"1K/unprogrammed notes: {notes}")
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notes = pb.update_preflight(mega_image, mega, fuses(0xFC)) # 1 KB, BOOTRST programmed
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if not any("staging slot" in n for n in notes):
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fail(f"1K/programmed notes: {notes}")
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notes = pb.update_preflight(mega_image, mega, fuses(0xFA)) # 2 KB, BOOTRST programmed
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if not any("application flash" in n for n in notes):
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fail(f"2K/programmed notes: {notes}")
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if pb.update_preflight(bytes((0xAA,)) * 8 + tiny.raw, tiny, None) != []:
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fail("tiny preflight should pass without fuses")
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# The walk-region refusal: BOOTRST aimed below the loader plus app data
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# in the walk span errors without --force; erased spans and unprogrammed
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# BOOTRST pass.
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deep = {0x7800: bytes((1,)) * 128}
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expect_error("walk region", lambda: pb.check_walk_region(deep, mega, fuses(0xFA), False), "--force")
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pb.check_walk_region(deep, mega, fuses(0xFA), True)
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pb.check_walk_region(deep, mega, fuses(0xFB), False) # BOOTRST unprogrammed
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pb.check_walk_region({0x7800: bytes((0xFF,)) * 128}, mega, fuses(0xFA), False)
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pb.check_walk_region(deep, mega, None, False) # fuses unknown: no check
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# The repairing verify: a mismatched page is rewritten rather than raised,
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# bounded so a fault that is not self-clearing cannot spin.
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class FakeLoader:
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"""A device whose first `bad` writes of any page land wrong."""
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def __init__(self, info, bad):
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self.info = info
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self.bad = bad
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self.flash = {}
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self.writes = 0
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def write_page(self, address, data):
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self.writes += 1
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self.flash[address] = bytes(len(data)) if self.bad > 0 else bytes(data)
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self.bad -= 1
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def read_flash(self, address, count):
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return self.flash.get(address, bytes(count))
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want = {0: bytes((i * 5) & 0xFF for i in range(128))}
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# One bad write, then good: repaired in place, and the caller never sees
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# an error. The rewrite is counted, so a silent no-op cannot pass.
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device = FakeLoader(info_of(pb, 0x7E00, 128, False, 0x8000), bad=1)
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device.write_page(0, want[0])
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pb.verify_pages(device, want, repair=True)
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if device.writes != 2:
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fail(f"repairing verify made {device.writes} writes, expected 2")
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# Without repair the same state raises, so the repair is what fixed it.
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device = FakeLoader(info_of(pb, 0x7E00, 128, False, 0x8000), bad=1)
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device.write_page(0, want[0])
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expect_error("verify without repair", lambda: pb.verify_pages(device, want), "verify failed")
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# A page that never comes good stops after RETRIES rewrites, and says so.
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device = FakeLoader(info_of(pb, 0x7E00, 128, False, 0x8000), bad=99)
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device.write_page(0, want[0])
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expect_error(
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"unrepairable page",
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lambda: pb.verify_pages(device, want, repair=True),
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"verify failed",
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f"after {pb.RETRIES} retries",
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)
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if device.writes != pb.RETRIES + 1:
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fail(f"unrepairable page took {device.writes} writes, expected {pb.RETRIES + 1}")
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print("test_planner: all planner and policy checks pass")
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if __name__ == "__main__":
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main()
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