The TCP/IP stack landed with its end-to-end test performed by hand: start
a listener, boot, type nettest, read the output. That is evidence once
and nothing afterwards, and it is exactly the kind of check that quietly
stops being run.
bootcheck -Net does the whole exchange. A listener runs on this host on a
port picked by binding one and letting go, the guest is told to connect
out to 10.0.2.2 at that port, and both ends are asserted: the guest
reports what it received, the listener reports what arrived. One side
alone proves much less than it looks -- a stack that completes a
handshake and then drops every byte satisfies any check made from inside
the guest.
The listener is a background job, a separate process, because this
harness has one hard rule: nothing may block the writer feeding QEMU's
stdin. A socket accept is precisely the wait that deadlocked two earlier
attempts at reading QEMU's output. It answers the protocol nettest
speaks and then closes -- the close is load-bearing, since nettest reads
until end of file and a listener that stayed open would hang the guest
rather than fail it.
The NIC is spelled out (-netdev user + -device e1000) rather than left to
QEMU's default. Other runs can take the default and still answer "did a
driver bind"; a run that asserts on an address should be reading its own
configuration.
/proc/netif is new, and the address is why. Until now the only report was
a line on the console at boot, which userland cannot read and a test can
only find by scraping the transcript. It gives interface, MAC, state,
address, netmask, gateway, MTU and frame counts. Named netif rather than
net on purpose: /proc/net is a *directory* on Linux, and a plain file
there would give ENOTDIR to anything reaching for /proc/net/dev, which is
worse than not having it. The counters are kept at the lwIP seam rather
than in the driver, because a frame the driver received and the netif
dropped never reached the stack.
Verified: 38 [ok], no failures. Eleven of them are new -- lwIP up, DHCP
obtaining 10.0.2.15 from SLIRP (a number nothing in the guest knows in
advance, so it is the exchange completing rather than a guess), the four
/proc/netif fields, frames counted in both directions, the handshake, the
reply read back, and the listener confirming HELLO-FROM-SCHOS arrived.
One bug found by writing it: $netPort was chosen after the command list
was built, so the guest ran `nettest 10.0.2.2` with no port and printed
its usage. An unset PowerShell variable interpolates to nothing rather
than failing, which is worth remembering next time a command in this
file looks right and behaves oddly.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The last three phases of the filesystem, which were written together and
touch the same files throughout -- kmount.c, objw.c and vfs.c are each
rewritten by all three -- so they land as one commit rather than three
that could not be built separately.
Durability. A transaction that reaches the platter out of order is worse
than one that never reached it: the uberblock can name a tree whose
blocks are still in the drive's write cache. bdirty/bflush give the
buffer layer an explicit barrier, ideflush issues ATA FLUSH CACHE and
usb_storage_flush the SCSI SYNCHRONIZE CACHE that means the same thing,
and a commit now waits for the data before it writes the root that
points at it. The uberblock groups are read newest-first with fallback,
so a volume whose newest roots are torn mounts at an older one and says
which generations were lost.
Reflink. Extents carry a refcount, so two objects can name the same
blocks and neither frees them while the other holds them. Exposed as
FICLONE -- Linux's ioctl value, so `cp --reflink` works unmodified --
and as cmd/reflink for the case where there is no cp to hand.
Attributes, and the one genuinely new idea here. attr.c stores named
values on an object, reachable through setxattr/getxattr/removexattr at
Linux's syscall numbers. On top of that, schfs_index declares an index
over an attribute name and schfs_query answers "which objects carry this
value" from the B-tree rather than by walking. A query against an
unindexed attribute is refused with an error, never silently answered by
a full scan: a query that quietly becomes a scan is worse than one that
admits it cannot help. cmd/schattr drives both.
Three bugs fixed on the way, each found by the numbers being wrong
rather than by inspection:
- statfs's f_fsid was declared int64[2]. Linux's fsid_t is two *ints*,
so every field after it landed one slot late: userland read f_frsize
out of f_namelen, got 255, and df reported a 32 MB root filesystem
as 1992 KB. It hid for as long as it did because the fields used to
be invented constants, so wrong numbers looked like the usual ones.
- struct inode's nlink was a short against SchFS's uint32, so a file
past 32767 names came back negative -- and iput frees an object
whose count reaches zero. It is an int now, signed on purpose, so an
underflow lands somewhere a check can see rather than wrapping.
- filewrite split every write to fit v1's log. That limit belongs to
the journal, not to writing, and SchFS makes one transaction of
whatever it is handed: a 1 MB write was becoming 170 commits and
170 flushes for nothing. fs_ops carries max_write now, and SchFS
sets no limit.
Also here: a real mount table, so `mount -t schfs /dev/hdb /mnt` shows
up in /proc/mounts -- df looks a path up there before it calls statfs at
all, so a mount missing from that list was invisible to it -- several
volumes mounted at once, snapshots mounted by name, and /proc/fsstat
with an rdtsc-based counter, which is the only instrument fine enough to
see inside a single syscall.
Verified: `make schfs-check` passes in full, including the sweep that
crashes the volume at each of 119 points mid-transaction and requires
every one to mount with exactly its committed data, and the case where
both newest uberblocks are rubbish and the volume still comes back. The
headless boot check passes with 27 [ok] and no failures, on a SchFS root.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Removes the "-unix" element and with it any trademark exposure to The
Open Group.
The split follows the ecosystem layout: SchOS is the system, and the
kernel has its own name. Kernel-identity strings are the only places
that take SchIFT -- uname(2) sysname, /proc/version, and the two licence
sentences that say "kernel" outright. That is what every Unix does here:
`uname -s` on Linux reports the kernel, not the distribution. Everything
a user reads as the product -- panic screen, boot menu, error prefixes,
docs, LICENSE, NOTICE -- is SchOS.
schunix.img is schos.img, the logo assets and the musl TLS patch are
renamed, and __SCHUNIX__ is __SCHOS__ (the define and the patch that
consumes it moved together).
Two things the rename broke, both found by the bootcheck suite:
- shmtest wrote "SCHUNIX-MMAP-OK" with a hardcoded length of 15 and
compared it back by hand-counted offsets (m[3]=='U', m[14]=='K').
The shorter marker left the write running two bytes past the literal
and the compare reading past the data, failing a file-backed mmap
that was working correctly. Now written and compared through one
constant with sizeof.
- bootcheck asserted a 31-byte file after appending to
"hello-from-schunix"; the shorter string makes it 29.
Both are the same mistake: a string literal whose length is written out
somewhere else. Full suite green -- base, Tty, Ps, Sock, Fb, Usb, Evdev.
An x86-64 operating system built from xv6, now largely rewritten: SMP,
a copy-on-write root filesystem (SchFS), PCI/USB/virtio drivers, a TTF
rasteriser, and a Linux-numbered syscall ABI.
No history before this point -- the tree was never under version control.
This commit exists so the rename that follows has something to undo to.
Nexoniarz