From: LIU Zhiwei <zhiwei_liu@c-sky.com>

Signed-off-by: LIU Zhiwei <zhiwei_liu@c-sky.com>
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Signed-off-by: Frank Chang <frank.chang@sifive.com>
---
 target/riscv/cpu.c      | 1 +
 target/riscv/cpu.h      | 1 +
 target/riscv/cpu_bits.h | 1 +
 target/riscv/csr.c      | 7 +++++++
 4 files changed, 10 insertions(+)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 228b9bdb5d..871c2ddfa1 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -317,6 +317,7 @@ static void riscv_cpu_reset(DeviceState *dev)
     env->mstatus &= ~(MSTATUS_MIE | MSTATUS_MPRV);
     env->mcause = 0;
     env->pc = env->resetvec;
+    env->vlenb = cpu->cfg.vlen >> 3;
 #endif
     cs->exception_index = EXCP_NONE;
     env->load_res = -1;
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index c02690ed0d..81c85bf4c2 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -111,6 +111,7 @@ struct CPURISCVState {
     target_ulong vl;
     target_ulong vstart;
     target_ulong vtype;
+    target_ulong vlenb;
 
     target_ulong pc;
     target_ulong load_res;
diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
index 79ae0accbc..62789e3720 100644
--- a/target/riscv/cpu_bits.h
+++ b/target/riscv/cpu_bits.h
@@ -63,6 +63,7 @@
 #define CSR_VCSR            0x00f
 #define CSR_VL              0xc20
 #define CSR_VTYPE           0xc21
+#define CSR_VLENB           0xc22
 
 /* VCSR fields */
 #define VCSR_VXSAT_SHIFT    0
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 77d371f385..6b05c631f4 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -197,6 +197,12 @@ static int read_vtype(CPURISCVState *env, int csrno, target_ulong *val)
     return 0;
 }
 
+static int read_vlenb(CPURISCVState *env, int csrno, target_ulong *val)
+{
+    *val = env->vlenb;
+    return 0;
+}
+
 static int read_vl(CPURISCVState *env, int csrno, target_ulong *val)
 {
     *val = env->vl;
@@ -1301,6 +1307,7 @@ static riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
     [CSR_VCSR] =                { vs,   read_vcsr,        write_vcsr        },
     [CSR_VL] =                  { vs,   read_vl                             },
     [CSR_VTYPE] =               { vs,   read_vtype                          },
+    [CSR_VLENB] =               { vs,   read_vlenb                          },
     /* User Timers and Counters */
     [CSR_CYCLE] =               { ctr,  read_instret                        },
     [CSR_INSTRET] =             { ctr,  read_instret                        },
-- 
2.17.1

On 7/10/20 3:48 AM, frank.chang@sifive.com wrote:
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 228b9bdb5d..871c2ddfa1 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -317,6 +317,7 @@ static void riscv_cpu_reset(DeviceState *dev)
>      env->mstatus &= ~(MSTATUS_MIE | MSTATUS_MPRV);
>      env->mcause = 0;
>      env->pc = env->resetvec;
> +    env->vlenb = cpu->cfg.vlen >> 3;
>  #endif
>      cs->exception_index = EXCP_NONE;
>      env->load_res = -1;
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index c02690ed0d..81c85bf4c2 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -111,6 +111,7 @@ struct CPURISCVState {
>      target_ulong vl;
>      target_ulong vstart;
>      target_ulong vtype;
> +    target_ulong vlenb;

I don't see that you need this.  The field is read-only, so the read_vlenb
function can just return

  env_archcpu(env)->cfg.vlen >> 3

directly.


r~