File nvgpu-power.sh of Package nv-dgpu-pwr

#!/bin/bash
# 61-nvgpu-power – early-boot helper for discrete GPUs (dracut)
# shellcheck shell=bash

# dracut helpers: getarg(), warn(), etc.
. /lib/dracut-lib.sh

set -ux

warn "nvgpu-power: start"

# ── 0) Fast-bail conditions ────────────────────────────────────────────────
# If resuming from hibernate or the nvidia/nouveau drivers are blacklisted, do nothing.
[ -n "${resume-}" ] && exit 0
case "$(cat /proc/cmdline)" in
  *modprobe.blacklist=nouveau*|*modprobe.blacklist=*nouveau*|*modprobe.blacklist=nvidia*|*modprobe.blacklist=*nvidia*) exit 0 ;;
esac

# ── 1) Inputs / defaults (override via kernel cmdline if needed) ───────────
# BUS_PCI is the bridge we "remove" before rescanning the bus.
BUS_PCI_DEFAULT="0000:00:1d.0"
TARGET_PCI_DEFAULT="0000:3c:00.0"   # device we want to appear

# Allow overrides:
#   rd.nvgpu_pci=<bridge BDF>       e.g. rd.nvgpu_pci=0000:00:1d.0
#   rd.nvgpu_target=<device BDF>    e.g. rd.nvgpu_target=0000:3c:00.0
BUS_PCI="${BUS_PCI_DEFAULT}"
arg=$(getarg rd.nvgpu_pci=)    && BUS_PCI="${arg#*=}"

TARGET_PCI="${TARGET_PCI_DEFAULT}"
arg=$(getarg rd.nvgpu_target=) && TARGET_PCI="${arg#*=}"

BUS_PATH="/sys/bus/pci/devices/${BUS_PCI}"
TARGET_PATH="/sys/bus/pci/devices/${TARGET_PCI}"

# ── 2) Remove→rescan loop: up to 10 iterations or until TARGET appears ─────
max_iters=10

for ((i=1; i<=max_iters; i++)); do
  # If the target device is present already, we’re done.
  if [ -e "${TARGET_PATH}" ]; then
    warn "nvgpu-power: target ${TARGET_PCI} present after ${i}-1 cycles"
    exit 0
  fi

  # If the bridge exists, try removing it to trigger a clean rescan.
  if [ -e "${BUS_PATH}/remove" ]; then
    echo 1 > "${BUS_PATH}/remove" || warn "nvgpu-power: failed to remove ${BUS_PCI}"
  else
    warn "nvgpu-power: ${BUS_PATH}/remove not present (iter ${i})"
  fi
  sleep 2
  
  # Rescan the PCI bus and give the kernel a moment.
  echo 1 > /sys/bus/pci/rescan
  sleep 2
done

# Final check after the last rescan
if [ -e "${TARGET_PATH}" ]; then
  warn "nvgpu-power: target ${TARGET_PCI} present after ${max_iters} cycles"
  exit 0
fi

warn "nvgpu-power: target ${TARGET_PCI} did not appear after ${max_iters} cycles"
exit 0