Section 22.8 Subset Naming Convention of the RISC-V ISA Specification
defines the canonical order for extensions in the ISA string. It is
silent on the position of the E extension however E is a substitute
for I so it must come early in the extension list order. A comment
is added to state E and I are mutually exclusive, as the E extension
will be added to the RISC-V port in the future.

Signed-off-by: Michael Clark <mjc@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
---
 target/riscv/cpu.c | 2 +-
 target/riscv/cpu.h | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 4851890..d2ae56a 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -26,7 +26,7 @@
 
 /* RISC-V CPU definitions */
 
-static const char riscv_exts[26] = "IMAFDQECLBJTPVNSUHKORWXYZG";
+static const char riscv_exts[26] = "IEMAFDQCLBJTPVNSUHKORWXYZG";
 
 const char * const riscv_int_regnames[] = {
   "zero", "ra  ", "sp  ", "gp  ", "tp  ", "t0  ", "t1  ", "t2  ",
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index cff02a2..3a0ca2f 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -71,6 +71,7 @@
 #define RV(x) ((target_ulong)1 << (x - 'A'))
 
 #define RVI RV('I')
+#define RVE RV('E') /* E and I are mutually exclusive */
 #define RVM RV('M')
 #define RVA RV('A')
 #define RVF RV('F')
-- 
2.7.0