--- gcc-8.3.0-orig/gcc/config/arm/t-arm-elf 2019-03-22 00:09:05.556706492 -0700
+++ gcc-8.3.0/gcc/config/arm/t-arm-elf  2019-03-22 23:17:59.776533196 -0700
@@ -62,9 +62,9 @@
 MULTILIB_REUSE      =

 # PART 2 - multilib build rules
-
-MULTILIB_OPTIONS     += marm/mthumb
-MULTILIB_DIRNAMES    += arm thumb
+# thumb/thumb2/interwork;@mthumb@march=armv7@mthumb-interwork
+MULTILIB_OPTIONS     += marm/mthumb march=armv7 mthumb-interwork
+MULTILIB_DIRNAMES    += arm thumb thumb2 interwork

 MULTILIB_OPTIONS     += mfpu=auto
 MULTILIB_DIRNAMES    += autofp
@@ -75,8 +75,19 @@
 MULTILIB_OPTIONS     += mfloat-abi=hard
 MULTILIB_DIRNAMES    += fpu

+
 # Build a total of 4 library variants (base options plus the following):
 MULTILIB_REQUIRED    += mthumb
+MULTILIB_REQUIRED    += mthumb-interwork
+MULTILIB_REQUIRED    += mthumb/march=armv7
+MULTILIB_REQUIRED    += mthumb/mthumb-interwork
+MULTILIB_REQUIRED    += mthumb/march=armv7/mthumb-interwork
+
+MULTILIB_MATCHES     += march?armv6-m=mcpu?cortex-m0
+MULTILIB_MATCHES     += march?armv7=mcpu?cortex-m3
+MULTILIB_MATCHES     += march?armv7=mcpu?cortex-m4
+MULTILIB_MATCHES     += march?armv7=mcpu?cortex-m7
+
 MULTILIB_REQUIRED    += marm/mfpu=auto/march=armv5te+fp/mfloat-abi=hard
 MULTILIB_REQUIRED    += mthumb/mfpu=auto/march=armv7+fp/mfloat-abi=hard

@@ -86,6 +97,7 @@
 MULTILIB_MATCHES     += $(foreach FPU, $(dp_fpus), \
              mfpu?auto=mfpu?$(FPU))

+
 MULTILIB_MATCHES     += march?armv5te+fp=march?armv5te

 MULTILIB_MATCHES     += $(foreach ARCH, $(all_early_arch), \