Index: head/sys/amd64/amd64/minidump_machdep.c
===================================================================
--- head/sys/amd64/amd64/minidump_machdep.c
+++ head/sys/amd64/amd64/minidump_machdep.c
@@ -448,9 +448,10 @@
 	}
 	else if (error == ECANCELED)
 		printf("Dump aborted\n");
-	else if (error == E2BIG)
-		printf("Dump failed. Partition too small.\n");
-	else
+	else if (error == E2BIG) {
+		printf("Dump failed. Partition too small (about %lluMB were "
+		    "needed this time).\n", (long long)dumpsize >> 20);
+	} else
 		printf("** DUMP FAILED (ERROR %d) **\n", error);
 	return (error);
 }
Index: head/sys/arm/arm/minidump_machdep.c
===================================================================
--- head/sys/arm/arm/minidump_machdep.c
+++ head/sys/arm/arm/minidump_machdep.c
@@ -340,9 +340,10 @@
 
 	if (error == ECANCELED)
 		printf("\nDump aborted\n");
-	else if (error == E2BIG || error == ENOSPC)
-		printf("\nDump failed. Partition too small.\n");
-	else
+	else if (error == E2BIG || error == ENOSPC) {
+		printf("\nDump failed. Partition too small (about %lluMB were "
+		    "needed this time).\n", (long long)dumpsize >> 20);
+	} else
 		printf("\n** DUMP FAILED (ERROR %d) **\n", error);
 	return (error);
 }
Index: head/sys/arm64/arm64/minidump_machdep.c
===================================================================
--- head/sys/arm64/arm64/minidump_machdep.c
+++ head/sys/arm64/arm64/minidump_machdep.c
@@ -414,9 +414,10 @@
 	}
 	else if (error == ECANCELED)
 		printf("Dump aborted\n");
-	else if (error == E2BIG)
-		printf("Dump failed. Partition too small.\n");
-	else
+	else if (error == E2BIG) {
+		printf("Dump failed. Partition too small (about %lluMB were "
+		    "needed this time).\n", (long long)dumpsize >> 20);
+	} else
 		printf("** DUMP FAILED (ERROR %d) **\n", error);
 	return (error);
 }
Index: head/sys/i386/i386/minidump_machdep_base.c
===================================================================
--- head/sys/i386/i386/minidump_machdep_base.c
+++ head/sys/i386/i386/minidump_machdep_base.c
@@ -348,9 +348,10 @@
 
 	if (error == ECANCELED)
 		printf("\nDump aborted\n");
-	else if (error == E2BIG || error == ENOSPC)
-		printf("\nDump failed. Partition too small.\n");
-	else
+	else if (error == E2BIG || error == ENOSPC) {
+		printf("\nDump failed. Partition too small (about %lluMB were "
+		    "needed this time).\n", (long long)dumpsize >> 20);
+	} else
 		printf("\n** DUMP FAILED (ERROR %d) **\n", error);
 	return (error);
 }
Index: head/sys/mips/mips/minidump_machdep.c
===================================================================
--- head/sys/mips/mips/minidump_machdep.c
+++ head/sys/mips/mips/minidump_machdep.c
@@ -348,9 +348,10 @@
 
 	if (error == ECANCELED)
 		printf("\nDump aborted\n");
-	else if (error == E2BIG || error == ENOSPC)
-		printf("\nDump failed. Partition too small.\n");
-	else
+	else if (error == E2BIG || error == ENOSPC) {
+		printf("\nDump failed. Partition too small (about %lluMB were "
+		    "needed this time).\n", (long long)dumpsize >> 20);
+	} else
 		printf("\n** DUMP FAILED (ERROR %d) **\n", error);
 	return (error);
 }
Index: head/sys/riscv/riscv/minidump_machdep.c
===================================================================
--- head/sys/riscv/riscv/minidump_machdep.c
+++ head/sys/riscv/riscv/minidump_machdep.c
@@ -399,9 +399,10 @@
 	}
 	else if (error == ECANCELED)
 		printf("Dump aborted\n");
-	else if (error == E2BIG)
-		printf("Dump failed. Partition too small.\n");
-	else
+	else if (error == E2BIG) {
+		printf("Dump failed. Partition too small (about %lluMB were "
+		    "needed this time).\n", (long long)dumpsize >> 20);
+	} else
 		printf("** DUMP FAILED (ERROR %d) **\n", error);
 	return (error);
 }