Linux's own r8169 through LDLS, deep idle, and the GPU plan

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

Makefile

@@ -1098,7 +1098,7 @@ $(BUILD)/lib/%.o: lib/%.S
 # stub.c are freestanding and build unchanged for either side, which is the
 # whole point of having written them that way.
 LDLS_GUEST = $(addprefix $(BUILD)/ldls/guest/, ko.o btf.o stub.o) \
-             $(addprefix $(BUILD)/ldls/guest/kpi/, kpi.o pci.o io.o net.o skb.o string.o work.o thunk.o)
+             $(addprefix $(BUILD)/ldls/guest/kpi/, kpi.o pci.o io.o net.o skb.o string.o work.o thunk.o base.o)
 
 $(BUILD)/ldls/guest/%.o: ldls/%.c ldls/ko.h ldls/btf.h ldls/stub.h
 	@mkdir -p $(BUILD)/ldls/guest
@@ -1106,7 +1106,7 @@ $(BUILD)/ldls/guest/%.o: ldls/%.c ldls/ko.h ldls/btf.h ldls/stub.h
 
 # The KPI -- the Linux symbols, implemented. Guest-only: it reaches /dev/pci
 # and /dev/netdev, which exist on SchOS and nowhere else.
-$(BUILD)/ldls/guest/kpi/%.o: ldls/kpi/%.c ldls/kpi/kpi.h
+$(BUILD)/ldls/guest/kpi/%.o: ldls/kpi/%.c ldls/kpi/kpi.h ldls/kpi/link_modes.inc
 	@mkdir -p $(BUILD)/ldls/guest/kpi
 	$(CC) $(CFLAGS) -I./ldls -c $< -o $@
 
@@ -1378,6 +1378,33 @@ ldls-stage:
 	@test -z "$(BTF)" || cp "$(BTF)" $(SYSROOT)/lib/modules/btf
 	@echo "staged into $(SYSROOT)/lib/modules -- this image is now yours alone"
 
+# Linux's r8169 and what it needs, from the kernel this machine runs, for
+# etc/schinit/ldls-r8169.job. The module set is r8169's dependency closure less
+# what LDLS answers itself (led-class, of_mdio, fwnode_mdio, fixed_phy), in load
+# order; the firmware is the RTL8168/8111 PHY patches. SchOS is GPL-2.0-or-later
+# and ships these knowingly -- see docs/plan/gpu.md.
+LDLS_KDIR ?= /run/current-system/kernel-modules/lib/modules/$(shell uname -r)/kernel
+LDLS_FWDIR ?= /run/current-system/firmware
+LDLS_R8169 = drivers/net/phy/mdio-bus drivers/net/phy/libphy \
+             drivers/net/phy/mdio_devres drivers/net/phy/realtek/realtek \
+             drivers/net/ethernet/realtek/r8169
+ldls-r8169:
+	@mkdir -p $(SYSROOT)/lib/modules $(SYSROOT)/lib/firmware/rtl_nic
+	@set -e; list=; for m in $(LDLS_R8169); do \
+	    f=$$(ls $(LDLS_KDIR)/$$m.ko* | head -1); n=$$(basename $$m).ko; \
+	    case $$f in *.xz) xz -dc $$f;; *.zst) zstd -qdc $$f;; *) cat $$f;; esac \
+	        > $(SYSROOT)/lib/modules/$$n; \
+	    list=$$list$${list:+,}/lib/modules/$$n; done; \
+	  cp /sys/kernel/btf/vmlinux $(SYSROOT)/lib/modules/btf; \
+	  printf '#!/bin/sh\nmkdir -p /var/log\nexec /bin/ldlsd %s /lib/modules/btf > /var/log/ldls-r8169.log 2>&1\n' \
+	      "$$list" > $(SYSROOT)/lib/modules/ldls-r8169.sh
+	@for f in $(LDLS_FWDIR)/rtl_nic/rtl8168*.fw*; do \
+	    n=$$(basename $$f); case $$n in \
+	    *.zst) zstd -qdc $$f > $(SYSROOT)/lib/firmware/rtl_nic/$${n%.zst};; \
+	    *.xz)  xz -dc $$f > $(SYSROOT)/lib/firmware/rtl_nic/$${n%.xz};; \
+	    *)     cp $$f $(SYSROOT)/lib/firmware/rtl_nic/;; esac; done
+	@echo "staged Linux r8169 ($(shell uname -r)) into $(SYSROOT)"
+
 ldls-unstage:
 	rm -rf $(SYSROOT)/lib/modules
 	@echo "removed"