Use microcode as CPU firmware

audit/internal/collector/cpu.go

@@ -6,30 +6,28 @@ import (
 	"fmt"
 	"log/slog"
 	"os"
+	"path/filepath"
 	"strconv"
 	"strings"
 )
 
-// collectCPUs runs dmidecode -t 4 and reads microcode version from sysfs.
-func collectCPUs(boardSerial string) ([]schema.HardwareCPU, []schema.HardwareFirmwareRecord) {
+// collectCPUs runs dmidecode -t 4 and enriches CPUs with microcode from sysfs.
+func collectCPUs(boardSerial string) []schema.HardwareCPU {
 	out, err := runDmidecode("4")
 	if err != nil {
 		slog.Warn("cpu: dmidecode type 4 failed", "err", err)
-		return nil, nil
+		return nil
 	}
 
 	cpus := parseCPUs(out, boardSerial)
-
-	var firmware []schema.HardwareFirmwareRecord
 	if mc := readMicrocode(); mc != "" {
-		firmware = append(firmware, schema.HardwareFirmwareRecord{
-			DeviceName: "CPU Microcode",
-			Version:    mc,
-		})
+		for i := range cpus {
+			cpus[i].Firmware = &mc
+		}
 	}
 
 	slog.Info("cpu: collected", "count", len(cpus))
-	return cpus, firmware
+	return cpus
 }
 
 // parseCPUs splits dmidecode output into per-processor sections and parses each.
@@ -180,7 +178,7 @@ func parseInt(v string) int {
 // readMicrocode reads the CPU microcode revision from sysfs.
 // Returns empty string if unavailable.
 func readMicrocode() string {
-	data, err := os.ReadFile("/sys/devices/system/cpu/cpu0/microcode/version")
+	data, err := os.ReadFile(filepath.Join(cpuSysBaseDir, "cpu0", "microcode", "version"))
 	if err != nil {
 		return ""
 	}