diff --git a/litex/soc/integration/cpu_interface.py b/litex/soc/integration/cpu_interface.py
index 5e25f8f41..506f95d9e 100644
--- a/litex/soc/integration/cpu_interface.py
+++ b/litex/soc/integration/cpu_interface.py
@@ -1,3 +1,5 @@
+import os
+
 from litex.gen import *
 
 from litex.soc.interconnect.csr import CSRStatus
@@ -9,18 +11,30 @@ cpu_endianness = {
 }
 
 def get_cpu_mak(cpu):
+    clang = os.getenv("CLANG", "")
+    if clang != "":
+        clang = bool(int(clang))
+    else:
+        clang = None
+
     if cpu == "lm32":
+        assert not clang, "lm32 not supported with clang."
         triple = "lm32-elf"
         cpuflags = "-mbarrel-shift-enabled -mmultiply-enabled -mdivide-enabled -msign-extend-enabled"
-        clang = ""
     elif cpu == "or1k":
-        triple = "or1k-linux"
-        cpuflags = "-mhard-mul -mhard-div -mror -mffl1 -maddc"
-        clang = "1"
+        # Default to CLANG unless told otherwise
+        if clang is None:
+           clang = True
+
+        triple = "or1k-elf"
+        cpuflags = "-mhard-mul -mhard-div -mror"
+        if clang:
+            triple = "or1k-linux"
+            cpuflags += "-mffl1 -maddc"
     elif cpu == "riscv32":
+        assert not clang, "riscv32 not supported with clang."
         triple = "riscv32-unknown-elf"
         cpuflags = "-mno-save-restore"
-        clang = ""
     else:
         raise ValueError("Unsupported CPU type: "+cpu)
     return [
@@ -28,7 +42,7 @@ def get_cpu_mak(cpu):
         ("CPU", cpu),
         ("CPUFLAGS", cpuflags),
         ("CPUENDIANNESS", cpu_endianness[cpu]),
-        ("CLANG", clang)
+        ("CLANG", str(int(clang)))
     ]
 
 
diff --git a/litex/soc/software/bios/main.c b/litex/soc/software/bios/main.c
index 819047a1a..d45ec8674 100644
--- a/litex/soc/software/bios/main.c
+++ b/litex/soc/software/bios/main.c
@@ -462,9 +462,15 @@ static int test_user_abort(void)
 
 	printf("Automatic boot in 2 seconds...\n");
 	printf("Q/ESC: abort boot\n");
-	printf("F7:    boot from serial\n");
+#ifdef FLASH_BOOT_ADDRESS
+	printf("F:     boot from flash\n");
+#endif
+	printf("S:     boot from serial\n");
 #ifdef CSR_ETHMAC_BASE
-	printf("F8:    boot from network\n");
+	printf("N:     boot from network\n");
+#endif
+#ifdef ROM_BOOT_ADDRESS
+	printf("R:     boot from embedded ROM\n");
 #endif
 	timer0_en_write(0);
 	timer0_reload_write(0);
@@ -478,19 +484,31 @@ static int test_user_abort(void)
 	while(timer0_value_read()) {
 		if(readchar_nonblock()) {
 			c = readchar();
-			if((c == 'Q')||(c == '\e')) {
+			if((c == 'Q')||(c == 'q')||(c == '\e')) {
 				puts("Aborted");
 				return 0;
 			}
-			if(c == 0x06) {
+#ifdef FLASH_BOOT_ADDRESS
+			if((c == 'F')||(c == 'f')) {
+				flashboot();
+				return 0;
+			}
+#endif
+			if((c == 'S')||(c == 's')) {
 				serialboot();
 				return 0;
 			}
 #ifdef CSR_ETHMAC_BASE
-			if(c == 0x07) {
+			if((c == 'N')||(c == 'n')) {
 				netboot();
 				return 0;
 			}
+#endif
+#ifdef ROM_BOOT_ADDRESS
+			if((c == 'R')||(c == 'r')) {
+				romboot();
+				return 0;
+			}
 #endif
 		}
 		timer0_update_value_write(1);
diff --git a/litex/soc/software/libcompiler_rt/Makefile b/litex/soc/software/libcompiler_rt/Makefile
index e317fdd7b..5db5c007e 100644
--- a/litex/soc/software/libcompiler_rt/Makefile
+++ b/litex/soc/software/libcompiler_rt/Makefile
@@ -1,7 +1,7 @@
 include ../include/generated/variables.mak
 include $(SOC_DIRECTORY)/software/common.mak
 
-ifeq ($(CPU),big)
+ifeq ($(CPUENDIANNESS),big)
 CFLAGS+=-D_YUGA_LITTLE_ENDIAN=0 -D_YUGA_BIG_ENDIAN=1 -Wno-missing-prototypes
 else
 CFLAGS+=-D_YUGA_LITTLE_ENDIAN=1 -D_YUGA_BIG_ENDIAN=0 -Wno-missing-prototypes