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feat(kernel): the GPT reader, and Zuse from a GPT identity partition

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The stick, increment 2 (plan 2026-10-26-stick-2-gpt-reader; docs/v4.0.0/
STICK.md 3 and 4: GPT for boot media and installed disks). kernel/src/gpt.c:
a CRC-32; gpt_read(), which checks the protective MBR, the primary header and
the partition-entry array (both CRCs, the revision, the sizes, the geometry);
and a partition as a blkio device, refusing blocks past its end. The two
StarshipOS partition types: identity 23BEBFE1-4817-4CF3-A537-9069BF159788,
Artemis BCD7B586-1C8E-4EEF-86A3-273A8D8EE624.

The v4 drive path: a GPT disk is used only through its StarshipOS identity
partition, and that partition -- never the disk -- is given to the block
subsystem, in a raw identity drive's place; a GPT disk with no StarshipOS
partition, or a damaged table ("GPT: a USB drive has a damaged partition
table -- not used"), is not attached (Captain Bob's ruling on the plan); a
disk with no GPT is read raw, as always. Pulling the drive detaches the
partition and ends her session. Reads only.

Red (amd64): gpt_zuse 193158, gpt_hotplug 193804, gpt_foreign 194713,
gpt_bad_crc 194947. Green: 195409, 195627, 195854, 200136; gpt_zuse aarch64
200424, riscv64 200839 (the 64 MiB partition attached, 48724 user blocks,
not the 72 MiB disk); the identity gate's and increment 1's sessions,
201119-203403, all pass.
Accepted (with the KERNEL_ARGS fix that follows): suite EXIT 0; 214300,
214507, 214911, POST 538/538, dict_hash 0xfec8c47cfc6f437f; test-32, 39
modules, 0 failures.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
rajames
2026-10-26 21:56:31 -04:00
co-authored by Claude Opus 5.5
parent 03099f2c51
commit 3cc4937c93
43 changed files with 3428 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files
scripts/qemu_session.py
+66 -3
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@@ -34,6 +34,11 @@ the stick's, plan 2026-10-26-stick-1-screen-and-keyboard.md):
alttab_before_pull Alt+TAB, then the drive pulled: black; re-attach draws the console
emergency_pull EMERGENCY_CONSOLE_ENABLED=1: Zuse added and pulled, the screen
still shows the running console, and it types
gpt_zuse a GPT drive, Zuse in its StarshipOS identity partition: recognised; the partition
is attached (run with --make KERNEL_ARGS=--log-level=info)
gpt_hotplug ... pulled: session ended; added again: prompt
gpt_foreign a GPT drive with only a Linux partition: no identity, not attached (info level)
gpt_bad_crc the gpt_zuse image with its header CRC broken: not used, said so, not attached
virtio_kbd aarch64/riscv64: QEMU's virtio keyboard types 7 ok
Needs only Python 3. One QEMU at a time (.claude/CLAUDE.md).
@@ -52,7 +57,7 @@ ap.add_argument("--make", default="")
ap.add_argument("--no-zuse", action="store_true")
a = ap.parse_args()
NO_ZUSE_MODES = {"headless", "hotplug", "midpull", "waitpull", "typeahead", "emergency",
NO_ZUSE_MODES = {"gpt_zuse", "gpt_hotplug", "gpt_foreign", "gpt_bad_crc", "headless", "hotplug", "midpull", "waitpull", "typeahead", "emergency",
"alttab_after_logout", "alttab_before_pull", "emergency_pull",
"screen_dark_until_login", "screen_console_after_login", "screen_dark_after_logout",
"kbd_typeahead"}
@@ -181,6 +186,32 @@ def key_line(line):
time.sleep(0.1)
# The two StarshipOS partition type GUIDs (docs/v4.0.0/plans/2026-10-26-stick-2-gpt-reader.md)
GPT_IDENTITY = "23BEBFE1-4817-4CF3-A537-9069BF159788"
GPT_LINUX = "0FC63DAF-8483-4772-8E79-3D69D8477DE4"
def make_gpt_image(path, ptype, payload, mib=72, break_crc=False):
"""A GPT disk image: one partition at LBA 2048, 131072 sectors (64 MiB), of type
`ptype`, holding `payload` from its start; optionally the primary header's CRC broken."""
subprocess.run(["truncate", "-s", f"{mib}M", path], check=True)
sf = shutil.which("sfdisk") or "/usr/sbin/sfdisk"
subprocess.run([sf, "--quiet", path], input=f"label: gpt\nstart=2048, size=131072, type={ptype}\n",
text=True, check=True)
subprocess.run(["dd", f"if={payload}", f"of={path}", "bs=512", "seek=2048", "conv=notrunc,sparse",
"status=none"], check=True)
if break_crc:
with open(path, "r+b") as f:
f.seek(512 + 16) # the primary header's HeaderCRC32
b = f.read(1)
f.seek(512 + 16)
f.write(bytes([b[0] ^ 0xFF]))
def blk_lines():
return count(r"blk: ")
def alt_tab():
qcmd("send-key", keys=[{"type": "qcode", "data": "alt"}, {"type": "qcode", "data": "tab"}])
time.sleep(1)
@@ -208,9 +239,9 @@ def screen():
return w, h, lit, px
def add_zuse(n):
def add_zuse(n, img=None):
qcmd("blockdev-add", driver="raw", **{"node-name": f"zuse{n}"},
file={"driver": "file", "filename": zimg})
file={"driver": "file", "filename": img or zimg})
qcmd("device_add", driver="usb-storage", bus="xhci0.0", port="1",
drive=f"zuse{n}", id=f"zusedev{n}")
@@ -406,6 +437,38 @@ elif m == "emergency_pull":
_, _, _, px2 = screen()
check("the screen changed with what was typed", px2 != px1)
elif m in ("gpt_zuse", "gpt_hotplug", "gpt_foreign", "gpt_bad_crc"):
gimg = os.path.join(work, "gpt.img")
make_gpt_image(gimg, GPT_LINUX if m == "gpt_foreign" else GPT_IDENTITY, zimg,
break_crc=(m == "gpt_bad_crc"))
check("no ok> for 10 s with no drive", not wait_for(ANYPROMPT, 10))
b0 = blk_lines()
add_zuse(1, gimg)
if m in ("gpt_zuse", "gpt_hotplug"):
check("Zuse: identity confirmed", wait_for(r"Zuse: identity confirmed from attached thumbdrive", 120))
check("[zuse@Hera] ok>", wait_for(PROMPT, 60))
# the identity partition (64 MiB), not the whole 72 MiB disk: a 64 MiB identity drive
# shows 48724 user blocks (the raw minted drive, logs/20261026-091010); the disk, 54868
users = re.findall(r"blk: disk .*?\((\d+) user", text())
check(f"the partition, not the disk, was attached (blk: lines {b0} -> {blk_lines()}, "
f"user blocks {users[-1] if users else None})",
blk_lines() > b0 and users and users[-1] == "48724")
n = count(PROMPT)
type_line("3 4 + .")
check("7 ok", wait_for(PROMPT, 60, n) and re.search(r"7\s+ok", text()[-400:]) is not None)
if m == "gpt_hotplug":
del_zuse(1)
check("session ended on detach", wait_for(r"Zuse: session ended -- reattach to re-authenticate", 60))
p = count(PROMPT)
add_zuse(2, gimg)
check("[zuse@Hera] ok> again", wait_for(PROMPT, 120, p))
else:
if m == "gpt_bad_crc":
check("the damaged table is said so", wait_for(r"GPT: a USB drive has a damaged partition table -- not used", 60))
check("no ok> for 30 s", not wait_for(ANYPROMPT, 30))
check("no identity", count(r"Zuse: identity confirmed") == 0)
check(f"not attached (blk: lines {b0} -> {blk_lines()})", blk_lines() == b0)
else:
check(f"known mode {m}", False)