The RTL8168 is now driven by Linux's r8169, unmodified, in a process.
`make ldls-r8169` stages it from the running kernel together with libphy,
mdio-bus, mdio_devres and the Realtek PHY driver, the kernel's BTF and
the RTL PHY firmware, and etc/schinit/ldls-r8169.job starts it at boot
with its log in /var/log/ldls-r8169.log. The native driver is out of the
registry; its code, now with Linux's 8168H setup, stays as the fallback.
LDLS grows what that needed:
- ldlsd loads a comma-separated module set in dependency order, each
linking against the ones before it, with BTF read before any
init_module runs;
- a driver core (bus match, driver probe), devres, kernel printf, real
udelay/msleep/ktime and 1000 Hz jiffies, phylib's bitmaps and
link_mode_params, firmware from /lib/firmware, and the symbols whose
stub zero was a lie (list validity, try_module_get, dev_err_probe,
eth_platform_get_mac_address);
- pdev->bus is a real pci_bus, and cmovcc from per-CPU memory is
rewritten like the other %gs forms.
In QEMU all five modules load, link and initialise, and r8169 registers
and finds no device. Probe and traffic are untested until real hardware.
The kernel turns ASPM off on Realtek NIC links at boot, as r8169 does
through pci_disable_link_state, which a process cannot.
Idle CPUs enter ACPI _CST's C2 (CC6 on Zen) by port read or MWAIT when
the APIC timer keeps running, instead of only ever halting at C1.
docs/plan/gpu.md: amdgpu and nouveau through LDLS, with measurements.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
Sixty-five headers sat side by side in include/, so `#include "irq.h"`
said nothing about where irq.h was or what it belonged to, and errno.h,
stat.h and fcntl.h at the top shadowed the system's for any host tool
built with -I./include. They are in folders now -- arch/ core/ fs/
dev/ gfx/ net/ uapi/ (and ldls/ for the Linux driver layer) -- and
every include names the folder, as Linux's do: "core/proc.h".
Done mechanically and checked the hard way: the kernel built from this
tree disassembles identically to the one built from the tree before
it. The full image boots, and userland is the same set of programs.
Paths in docs and comments follow; docs/guides/layout.md has a table
of what is where, and tools/fix-includes.py rewrites old-style
includes from the folders in the tree, for code written before this.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
A native driver written from the NVMe 1.4 base specification. It resets
the controller the firmware left running, then sets up an admin queue and
one I/O queue pair. Completion is polled, with interrupts disabled at the
queue, for the same reason AHCI polls: without AML, interrupt routing on
real hardware cannot be trusted. Each active namespace with 512-byte to
4 KB sectors and no metadata is registered as nvme<C>n<N>, the name
Linux uses, and its GPT is read like any other disk's.
Tested under QEMU q35: disk.img on NVMe as the only disk boots through
OVMF, roots on nvme0n1p2, and writes read back after sync. A
4 KB-sector namespace registers.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
q35 stopped with "no root filesystem" because its disk is SATA, like
every PC since 2008, and SchOS only had IDE. And SchFS could only sit
on a whole raw device, so nothing could boot from a disk that also
carried an ESP.
- include/blkdev.h, kernel/dev/blkdev.c: a registry of block devices
found at probe time, numbered from 4. A disk's GPT (or MBR) is read
when it registers, and each partition becomes a device whose block 0
is the partition's first sector. SchFS needs no format change to live
in a partition; a Linux SchFS driver will see the same bytes on
/dev/sdX2. SchFS has its own GPT type:
47138FA9-B79C-47A6-9F7D-AC1F7F572D5E.
- AHCI driver, written from the AHCI 1.3.1 spec: BIOS handoff,
COMRESET when the link is down, IDENTIFY, 48-bit DMA read/write,
FLUSH. Completion is polled, so the root disk does not depend on
interrupt routing.
- USB sticks also register as usb0, so their partitions are found.
- The root probe tries registered devices between USB and IDE,
SchFS-typed partitions first.
- make disk / tools/posix/mkdisk.sh: a GPT image with a 64 MB ESP and
a SchFS partition, ready to dd to a stick or a disk.
Tested in QEMU q35: the old two-disk setup roots on sata1; disk.img as
the only SATA disk roots on sata0p2; disk.img as a USB stick (firmware
boots from it) roots on usb0p2. Writes survive sync in each case.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HH7xukt4aaiGj1nQEAoQf1
Two NICs, and unlike the RTL8111 last commit, QEMU emulates both -- so both
are tested rather than reasoned about.
**RTL8139** is its own driver and not a mode of the 8169, because it is its own
chip. No descriptor rings: the receiver is one circular buffer the chip writes
packets into back to back behind four-byte headers, and the transmitter is four
fixed slots. Putting both programming models behind one set of function
pointers is how a mode flag ends up threaded through every path.
Three details are the whole driver. CAPR runs sixteen bytes behind the true
read position -- a quirk of the part, not an off-by-one. WRAP means the chip
runs a packet past the end of the buffer rather than splitting it, so the 8 KB
buffer is allocated as 8 KB + 16 + one maximum frame; getting that wrong is a
chip writing past its allocation at line rate. And a length field of 0xFFF0
means "still writing this one", so treating it as a length copies a partial
packet and loses the alignment for everything after it.
**The e1000 now matches the PCIe 8257x parts.** Its header refused them, with
a note saying they "differ in NVM access and initialisation, and claiming a
device this driver has not been shown to initialise is worse than not claiming
it". That was right, and the second half is answerable: QEMU emulates the
82574L, so it can be *shown* to initialise.
What differs turned out to be one register. EERD moved its address field from
bits 8-15 to bits 2-15 and its done bit from 4 to 1; the rings, RCTL, TCTL and
ICR are identical. So there is a per-instance flag for the NVM layout and seven
more ids -- not a second copy of four hundred lines of ring code. The wrong
pair of constants fails silently, reading the wrong word or waiting for a bit
that never sets, and the MAC comes out as zeroes; that is why it is named in
the header rather than papered over.
Still refused: the ICH/PCH parts (82562, 82577-82579, I217-I219), which put the
PHY behind a MAC-PHY interconnect and need a different bring-up nothing here
can test.
Tested, each booted alone: rtl8139 (10ec:8139) and 82574L (8086:10d3) both bind,
read a real MAC, complete DHCP and ping 4 of 4 with no loss. The classic
82540EM does the same, which is the regression that mattered for the NVM
change. Both supported display configurations: one boot each, no traps, no
panics, socktest and memfdtest green.
Also recorded: the Chromebox CN62 carries an RTL8111, not an Intel part, so
last commit's driver covers it too.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The laptop's NIC is an RTL8111H, and the request was to add it to LDLS.
Measuring it is what changed the answer, so the measurement is the commit
message: r8169.ko (6.18.52) has **183 undefined symbols, 130 of them not
implemented by ldls/kpi/, and 35 of those 130 are phylib** --
phy_connect_direct, phy_start, mdiobus_read, genphy_soft_reset and the rest.
phylib is a subsystem with a link state machine, not a set of leaf calls, and
LDLS's usual answer for an unimplemented symbol -- a stub that reports itself
and returns zero -- is exactly wrong for it. phy_start returning zero means the
link never comes up and there is nothing to look at. The 8139too that ldls.md
uses as its model has no phylib dependency, which is why that one was
tractable and this one is not.
So: a native driver. It reaches the PHY through the chip's own MII window --
PHYAR is one register that is a whole MII bus -- and skips the subsystem. Less
work than the port, no GPL entanglement, no firmware blob, no coupling to one
Linux version, and it covers the whole RTL8111/8168 family because all of it
answers to 10EC:8168. The register layout is a fact about the hardware, taken
the way ldls.md section 3 says facts may be taken; the expression is this
tree's, in the same shape as the e1000 beside it.
**It has not run on hardware, and that is not a hedge.** QEMU emulates rtl8139
and nothing else from Realtek, and the 8139 is a different programming model --
a circular receive buffer rather than descriptors -- so it is deliberately not
in the match table. What is verified: it builds, its presence changes nothing
on a machine without the device, and with an rtl8139 on the bus it correctly
leaves it unclaimed. What is not: every register write, on a real part.
The probe therefore says everything a first bug report needs, with cprintf
rather than kinfo so it reaches the screen of a machine with no serial port:
r8169: xid 5c0, 1c:1b:b5:xx:xx:xx, irq 11, link up (bmsr 796d)
xid is the hardware version from the top of TxConfig -- the PCI device id has
been 8168 for twenty years and says nothing. bmsr is MII register 1: bit 2 is
link, bit 5 is autonegotiation complete. Those four facts separate "the chip is
not there" from "the PHY sees nothing" from "the rings are wrong".
Two constants were wrong in the first draft and are recorded because both would
have worked quietly. RxConfig had 0x7700 for "unlimited": MXDMA is bits 8-10
and RXFTH is bits 13-15, so that was one bit short of a full burst and a
half-full FIFO threshold. And CPCR bit 3 was being set under a comment calling
it "PCI multiple read/write" -- bit 3 is PCIDAC, 64-bit addressing, and bit 4
is what the comment described; neither is wanted, so the write is gone.
Both supported configurations: one boot each, no traps, no panics, socktest and
memfdtest green.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
A program that wants to make a sound opens /dev/dsp, writes PCM, and closes
it. That is what UNIX audio has always been and it now exists here:
tone 440 2
Three pieces, in the order a sample passes through them. **/dev/dsp** is a
character device where write() is audio and a handful of OSS ioctls say what
the samples are. **AudioEngine** is everything above a driver that is not
specific to a chip -- the format, whether there is room, and what a write does
when there is not. **A driver** is bound by class, exactly as a display driver
is: device_find_class(DEVCLASS_AUDIO).
OSS numbering rather than something new, because every UNIX audio program ever
written already knows it and the only thing a different set would achieve is
making ports harder. They are read/write ioctls, which is the part that
matters: a program asks for 44100, the device sets 48000 and writes 48000
back, the program resamples. One that ignores the answer plays 9% fast, and
that is its bug rather than the driver's.
**The engine is deliberately one stream.** Mixing several programs is a real
feature with a real design behind it, and building it before anything had
played a single sound would be exactly what docs/plan/1.0.md keeps a register
for: work that exists and is connected to nothing. The second program that
wants to play at the same time is what should cause it to be written.
**audio_wait() sleeps on the timer tick, not on the device.** That looks like
the lazy choice and is not: a ring that drains is a ring with room, so asking
again in ten milliseconds always makes progress, whereas sleeping on the card
makes audio depend on an interrupt arriving. On a machine whose line is
misrouted that is not a stutter, it is a writer that never wakes. The handler
still accounts for finished buffers -- deleting it would cost efficiency, not
correctness -- and it retires descriptors through the same `tail` pointer
queue() uses, so the two cannot disagree about what is in flight.
**AC'97 first because HDA is two unproven things at once.** It is the simplest
audio device that exists on real machines and in QEMU both. Intel HDA is what
the laptop actually has and is a much larger driver; writing it against an
interface nothing had ever played through would have meant debugging the
driver and the interface simultaneously. HDA arrives as a second
struct audio_ops and nothing above it changes -- which is the entire point of
the class.
Two things the wiring needed: PCI class 0x04 now maps to DEVCLASS_AUDIO (the
driver bound and /proc/devices showed it, but audio_get() found nothing,
because the class byte had never been translated), and include/x86.h grew
inw() -- AC'97's mixer is all 16-bit registers and reading one a byte at a
time returns the low half twice on some codecs.
**Tested by measuring what came out, not by not crashing.** QEMU's wav backend
writes the guest's audio to a file; `tone 440 2` produced 1.97 seconds of
44.1 kHz stereo with peak amplitude 14177 against the generator's table
maximum of 14178, and 880 zero crossings per second -- 440 Hz exactly. wav is
on every QEMU target rather than a host backend, because a build machine may
have no sound card and it is the only backend whose output can be checked.
Both supported configurations: one boot each, no traps, no panics, socktest
and memfdtest green.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Same disease as the network stack, one subsystem over. kernel/dev/vga.c
was three things wearing one name: the owner of the framebuffer, a
bitmap drawing library, and the text console. Only the first is a
driver, and because they shared a file they shared a prefix -- so
panic.c drew the crash screen with vga_fill_rect, console.c printed with
vga_putc, /dev/fb0 handed out vga_fb_phys, and every one of those files
named a display driver it had no business knowing about.
Split three ways:
- kernel/drivers/gpu/vga/vga_fb.c owns the VBE framebuffer -- the mode
the loader programmed and handed over, the aperture, and the display
class vtable. It is a driver and now lives with the driver that
finds the card on the bus.
- kernel/dev/gfx.c draws: pixels, shapes, glyphs, the cursor, scroll,
the ANSI erase operations. It names no driver. The framebuffer
arrives through gfx_attach_scanout(), so a driver publishes what it
owns and this file draws on it without knowing what it is.
- include/gfx.h is the interface, and says why it is deliberately not
the display class: that one is about frames -- acquire, present,
vblank -- and the crash screen has to work when nothing else does.
main() no longer calls a display driver. platform_register_devices()
takes the framebuffer address and brings up whatever owns it, which is
where driver names belong; kernel/drivers/registry.c is the file whose
entire job is naming every driver in the kernel.
virtio-gpu got the e1000 treatment as well: instances in an array, the
instance hung on dev->priv by an `attached` hook, and every op reading
it rather than a file-static. It refused the second adapter outright
before, which is not hypothetical -- integrated plus discrete is an
ordinary laptop. The VGA driver deliberately has no such hook, and says
so: there is one framebuffer the loader programmed however many
VGA-class controllers the bus turns up, and a second one publishing the
same scanout is the truth rather than a bug.
Private headers moved next to their drivers: include/virtio.h and
include/xhci.h each had exactly one includer. include/ is for headers
the rest of the kernel needs.
Deleted rather than moved: consoleinit() programmed the sixteen ANSI
colours into the VGA DAC and disabled text-mode blink, by writing ports
0x3C0-0x3C9 from the console. The comment three lines above the colour
table already said this does nothing in a 32bpp linear mode -- there is
no palette to index -- so it was both dead and in the wrong file.
Verified, and this is a refactor so the evidence is that nothing moved:
- bootcheck -Fb -Net: 59 [ok], no failures. That covers the console
through every command, /dev/fb0's geometry, writing pixels through
write() and mapping the framebuffer through mmap.
- make crashshot: the crash screen renders exactly as before --
shapes, glyphs, logo and QR code -- which is the whole of gfx.c
exercised at once, in a panic, with the scanout attached by a driver.
- make schcom-test: five pixel assertions from the host oracle still
pass, so the display class and the compositor above it are unmoved.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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