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docs/ was ten files where a plan, a description, a guide and a bug report all
sat next to each other. It is now architecture/ (what SchOS is), plan/ (what it
will be), guides/ (how to work on it) and history/ (why it is like this), with
an index that states the one rule holding it together: when something is
finished it moves from plan/ to architecture/ and is rewritten as a description
of the thing rather than a record of building it.
A ticked checkbox says the work happened. It does not say what the work
*produced*, and six months later the checkbox is all that is left. The network
stack proved the point: finished, verified end to end, and for a month the only
description of it anywhere was a checkbox four levels of indentation deep.
So roadmap.md went from 534 lines to 181 -- nothing deleted, the done work
graduated. Seven subsystems that were finished and undescribed now have
descriptions: boot, kernel, syscalls, filesystem, networking, graphics, usb,
init. Every one ends with "What it does not do", which is the section that pays;
a document listing only strengths is marketing, and the reader who needs it most
is the one about to trip over a limitation nobody wrote down.
schfs.md still opened with "phases 1 through 3 1/2 are done, phase 4 is next"
long after all five had landed. It is a description now, with the phase record
and the hard-won bugs moved to history/.
Three corrections found on the way, all load-bearing:
* projects/schcom/README.md claimed SCM_RIGHTS was done. There is no
sendmsg/recvmsg in the kernel at all, and an entire GUI plan rested on it.
* The root README said "No TCP/IP" months after the stack landed.
* history/kernel.md sec.7 was marked "in progress" on a problem that process
groups solved.
Also adds plan/1.0.md, which draws a finish line so the open list stops being
infinite, and marks schwm/ and schde/ superseded: in Wayland the compositor is
the window manager, so that split dissolves rather than being abandoned.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VQ7Qx8E1q1M1bbCq8QLHS2
2.9 KiB
| name | description | metadata | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| schunix-network-stack-choice | Don't write TCP from scratch — and don't take NetBSD's either; the licence and porting evidence for lwIP vs FreeBSD. |
|
Decided 2026-08-08. Nexoniarz: "we should take FreeBSD or NetBSD and their Network stuff because it's going to be hell making own TCP/IP." Agreed on the premise — TCP is the one part of a network stack where writing it yourself is a bad trade. It is not the packet format that is hard; it is congestion control, retransmission, window management and twenty years of corner cases that only appear against a real peer.
But the source matters, and NetBSD is the wrong one.
The licence evidence (all verified, not assumed)
| advertising clause? | |
|---|---|
NetBSD sys/netinet/tcp_input.c, tcp_output.c |
Yes — the WIDE Project's 4-clause |
FreeBSD sys/netinet/tcp_input.c |
No — UC, Swinburne, FreeBSD Foundation, Juniper |
| lwIP | No — BSD-3, Swedish Institute of Computer Science |
The NetBSD clause belongs to WIDE, not Berkeley, so the 1999 rescission does
not reach it. Checked FreeBSD's file directly from raw.githubusercontent.com;
zero matches for "All advertising materials". Checked lwIP's COPYING; likewise
zero. This reverses the older assumption in docs/plan/roadmap.md that NetBSD
was the intended starting point.
The porting evidence, which matters more
FreeBSD's sys/netinet is not a library. tcp_input.c alone is 122 KB and
reaches into mbufs, epoch(9), netisr, VNET, uma(9), sockbufs, inpcb hash
tables and FreeBSD's locking. Taking it means porting FreeBSD's kernel
infrastructure first and finding the TCP underneath — the same conclusion
docs/plan/roadmap.md §1 already reached about sys/dev/usb.
lwIP was written for the situation Schunix is actually in: a small OS with a raw Ethernet driver and no infrastructure. Port layer is a handful of files, no dependency on the host allocator or locking, and it brings ARP, IPv4, ICMP, UDP, TCP, DHCP and DNS.
Recommendation: lwIP first, FreeBSD as the reference to check against.
Practical notes
- Nexoniarz deleted the NetBSD checkout (
src-trunk/) for space and said it can be re-fetched. Do not clone a whole BSD tree — a sparse checkout ofsys/netandsys/netinetis all that has ever been needed, and the space complaint was legitimate. - One-file fetches from
raw.githubusercontent.comare enough for a licence check and cost nothing. That is how both findings above were made. - Shell trap hit while doing this:
grep -cexits 1 when it finds zero matches, socmd && grep -c ... || echo "failed"prints the failure message on a perfectly successful run. Nearly reported "no network access" when the fetch had worked. - Whichever is chosen, it needs a
NOTICEentry — see schunix-licensing.