1 files changed, 67 insertions, 38 deletions
diff --git a/bin/realtime-suggestions b/bin/realtime-suggestions
index cf5f599..fa0c82e 100755
--- a/bin/realtime-suggestions
+++ b/bin/realtime-suggestions
@@ -5,7 +5,10 @@ set -euo pipefail
 warning="WARNING:"
 change="CHANGE:"
 info="INFO:"
-kernel_config="/proc/config.gz"
+
+kernel_release=""
+kernel_config=""
+
 sysctl_ref="(see \`man 5 sysctl.conf\`, \`man 5 sysctl.d\` or \`man 8 sysctl\` for reference)"
 
 check_root() {
@@ -22,6 +25,43 @@ check_kernel_name() {
   fi
 }
 
+get_kernel_config_location() {
+  local default_location="/proc/config.gz"
+  local boot_location="/boot/config-${kernel_release}"
+  if [ -r "${default_location}" ]; then
+    echo "${default_location}"
+    return
+  elif [ -r "${boot_location}" ]; then
+    echo "${boot_location}"
+    return
+  else
+    echo ""
+    return
+  fi
+}
+
+kernel_config_has() {
+  local config="$1"
+  local grep_cmd="zgrep"
+  if [[ "${kernel_config}" != *.gz ]]; then
+    grep_cmd="grep"
+  fi
+  if $grep_cmd -q "$config" "$kernel_config"; then
+    return 0
+  else
+    return 1
+  fi
+}
+
+kernel_cmdline_has() {
+  local search="$1"
+  if ! grep -q "${search}" /proc/cmdline; then
+    return 1
+  else
+    return 0
+  fi
+}
+
 check_virtualization() {
   local virt_type=""
   if command -v systemd-detect-virt >/dev/null 2>&1; then
@@ -124,56 +164,38 @@ check_cpu_governor() {
 check_config_high_res_timers() {
   local config="CONFIG_HIGH_RES_TIMERS=y"
   local config_ref="(see \`man 7 time\` for reference)"
-  if [ -e "${kernel_config}" ]; then
-    if ! zgrep -q "$config" "$kernel_config"; then
-      echo "$change CONFIG_HIGH_RES_TIMERS needs to be activated for your kernel $config_ref."
-    fi
-  else
-    echo "$change $kernel_config could not be found or accessed."
+  if ! kernel_config_has "$config"; then
+    echo "$change CONFIG_HIGH_RES_TIMERS needs to be activated for your kernel $config_ref."
   fi
 }
 
 check_config_no_hz() {
   local configs=( 'CONFIG_NO_HZ_COMMON=y' 'CONFIG_NO_HZ_FULL=y' 'CONFIG_NO_HZ=y')
   local config_ref="(see https://elinux.org/Kernel_Timer_Systems#Dynamic_ticks for reference)"
-  if [ -e "${kernel_config}" ]; then
-    for config in "${configs[@]}"; do
-      if ! zgrep -q "$config" "$kernel_config"; then
-        echo "$change $config needs to be set for your kernel for 'dynamic ticks' support $config_ref."
-      fi
-    done
-  else
-    echo "$change $kernel_config could not be found or accessed."
-  fi
+  for config in "${configs[@]}"; do
+    if ! kernel_config_has "$config"; then
+      echo "$change $config needs to be set for your kernel for 'dynamic ticks' support $config_ref."
+    fi
+  done
 }
 
 check_config_preempt_rt() {
-  local config1="CONFIG_PREEMPT_RT=y"
-  local config2="CONFIG_PREEMPT_RT_FULL=y"
+  local configs=( 'CONFIG_PREEMPT_RT=y' 'CONFIG_PREEMPT_RT_FULL=y' )
   local config_ref="(see https://wiki.linuxfoundation.org/realtime for reference)"
-  if [ -e "${kernel_config}" ]; then
-    if ! zgrep -q "$config1" "$kernel_config" && ! zgrep -q "$config2" "$kernel_config"; then
-      echo "$change The PREEMPT_RT patch set is not available on your kernel $config_ref."
-    fi
-  else
-    echo "$change $kernel_config could not be found or accessed."
+  if ! kernel_config_has "${configs[0]}" && ! kernel_config_has "${configs[1]}"; then
+    echo "$change The PREEMPT_RT patch set (${configs[*]}) is not available on your kernel $config_ref."
   fi
 }
 
 check_config_irq_forced_threading() {
-  local config1="CONFIG_PREEMPT=y"
-  local config2="CONFIG_IRQ_FORCED_THREADING=y"
+  local configs=( 'CONFIG_IRQ_FORCED_THREADING=y' 'CONFIG_PREEMPT=y' )
   local config_ref="(see https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html for reference)"
-  if [ -e "${kernel_config}" ]; then
-    if zgrep -q "$config2" "$kernel_config"; then
-      if ! zgrep -q "$config1" "$kernel_config" && ! grep -q "threadirqs" /proc/cmdline; then
-        echo "$change Without $config1 on your kernel, you can still use the threadirqs kernel parameter $config_ref." 
-      fi
+  if ! kernel_config_has "${configs[0]}"; then
+    if kernel_config_has "${configs[1]}" && ! kernel_cmdline_has "threadirqs"; then
+      echo "$change Without ${configs[0]} but with ${configs[1]} support on your kernel, you can still use the threadirqs kernel parameter $config_ref." 
     else
-      echo "$change Use a kernel with $config2 $config_ref."
+      echo "$change Your kernel neither supports ${configs[0]} nor ${configs[1]}." 
     fi
-  else
-    echo "$change $kernel_config could not be found or accessed."
   fi
 }
 
@@ -228,6 +250,17 @@ check_for_useful_tools() {
 check_kernel_name
 check_root
 check_virtualization
+kernel_release=$(uname -r)
+kernel_config=$(get_kernel_config_location)
+if [ -n "${kernel_config}" ]; then
+  check_config_high_res_timers
+  check_config_no_hz
+  check_config_preempt_rt
+  check_config_irq_forced_threading
+else
+  echo "$warning The kernel config could not be found or accessed (e.g. /proc/config.gz or below /boot/config-*)."
+fi
+
 check_filesystems
 check_groups
 check_ulimits
@@ -236,10 +269,6 @@ check_legacy_timers
 check_vm_swappiness
 check_cpu_governor
 check_cpu_dma_latency
-check_config_high_res_timers
-check_config_no_hz
-check_config_preempt_rt
-check_config_irq_forced_threading
 check_coupled_interrupts
 check_irqbalance
 check_for_useful_tools