PCI drivers took their interrupt from INTERRUPT_LINE. On real hardware
that is the 8259's number, not the IOAPIC pin the device is wired to
(that is in ACPI _PRT, which needs AML), so nothing ever arrived. xHCI
is entirely interrupt-driven, so the USB keyboard and a USB root would
have hung even on a clean boot. Under QEMU the two numbers agree,
which is why it never showed.
- pci_irq_attach()/pci_irq_detach(): MSI, then MSI-X if the driver
allows it, then INTx. The handler is registered before MSI is
enabled, so no edge is lost. xHCI, e1000, r8169 and rtl8139 use it.
- Lines 24-29 are MSI vectors. The LAPIC error vector moves from 19,
which is a PCI pin on Intel chipsets, to 30. Nothing is placed at or
above vector 64 (T_SYSCALL).
- A storming line is masked and its handlers are polled instead of
being left to eat the CPU. A level line that has had a handler for 2 s
and never fired is polled every tick by a kernel thread.
Tested in QEMU q35 with the root on a USB stick: xHCI and e1000e on
MSI; then MSI disabled and INTx deliberately misrouted, where xHCI got
zero interrupts and the root still mounted through the poller. i440fx
INTx and the rtl8139 hand-over are unchanged.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HH7xukt4aaiGj1nQEAoQf1
The kernel's rtl8139 driver had no release hook, so /dev/pci refused
every request for the card ("the kernel would not release it") and a
hosted 8139too could never run on a machine where this driver probed
first.
release() follows e1000_release(): silence the chip before unhooking the
interrupt, reset it and clear bus mastering so it stops writing into its
buffers, take the interface out of the stack, then give the DMA buffers
back.
Tested in QEMU: ldlsd takes the card from the kernel, 8139too probes it,
DHCP binds ldls0, and ping 10.9.0.2 gets 3 of 3 replies.
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>
