# lwip.sys

`lwip.sys` is the TCP/IP stack provider driver. It owns lwIP, `tcpip_thread`,
netif attach, DNS, TCP, UDP, and the provider-side socket implementation.

The core kernel owns only:

- `NET_DEVICE` registration and Ethernet frame transport
- `NET_STACK_PROVIDER` registration
- process-owned socket handles
- syscall/user-memory boundaries

Build notes:

- Do not use lwIP CMake.
- `build.bat` compiles the sources listed in `drivers/net/lwip/lwip_sources.txt`.
- Include directories:
  - `code/drivers/net/lwip/include`
  - `code/drivers/net/lwip/third_party/lwip/src/include`

Load order:

`drivers.ini` v2 uses `class.network-stack` with `after=network-adapter`.
NIC modules initialize first; lwIP attaches to already registered adapters.
The stack also initializes normally when no physical NIC is present.