diff --git a/sys/arm64/include/pmc_mdep.h b/sys/arm64/include/pmc_mdep.h
--- a/sys/arm64/include/pmc_mdep.h
+++ b/sys/arm64/include/pmc_mdep.h
@@ -38,7 +38,10 @@
 #include <dev/hwpmc/hwpmc_arm64.h>
 
 union pmc_md_op_pmcallocate {
-	uint64_t		__pad[4];
+	uint32_t		pm_md_flags;
+#define	PM_MD_RAW_EVENT		0x1
+	uint32_t		__pad32;
+	uint64_t		__pad[3];
 };
 
 /* Logging */
diff --git a/sys/dev/hwpmc/hwpmc_arm64.c b/sys/dev/hwpmc/hwpmc_arm64.c
--- a/sys/dev/hwpmc/hwpmc_arm64.c
+++ b/sys/dev/hwpmc/hwpmc_arm64.c
@@ -181,11 +181,14 @@
 	}
 	pe = a->pm_ev;
 
-	config = (uint32_t)pe - PMC_EV_ARMV8_FIRST;
-	if (config > (PMC_EV_ARMV8_LAST - PMC_EV_ARMV8_FIRST))
-		return (EINVAL);
+	/* Adjust the config value if needed. */
+	config = (uint32_t)pe;
+	if ((a->pm_md.pm_md_flags & PM_MD_RAW_EVENT) == 0) {
+		config -= PMC_EV_ARMV8_FIRST;
+		if (config > (PMC_EV_ARMV8_LAST - PMC_EV_ARMV8_FIRST))
+			return (EINVAL);
+	}
 	pm->pm_md.pm_arm64.pm_arm64_evsel = config;
-
 	PMCDBG2(MDP, ALL, 2, "arm64-allocate ri=%d -> config=0x%x", ri, config);
 
 	return (0);