[qemu,v14,15/15] target/riscv: rvv: Add option 'rvv_ta_all_1s' to enable optional tail agnostic behavior

Commit Message

~eopxd April 28, 2022, 3:26 a.m. UTC

From: eopXD <[e-mail]>

According to v-spec, tail agnostic behavior can be either kept as
undisturbed or set elements' bits to all 1s. To distinguish the
difference of tail policies, QEMU should be able to simulate the tail
agnostic behavior as "set tail elements' bits to all 1s".

There are multiple possibility for agnostic elements according to
v-spec. The main intent of this patch-set tries to add option that
can distinguish between tail policies. Setting agnostic elements to
all 1s allows QEMU to express this.

This commit adds option 'rvv_ta_all_1s' is added to enable the
behavior, it is default as disabled.

Signed-off-by: eop Chen <[e-mail]>
Reviewed-by: Frank Chang <[e-mail]>
Reviewed-by: Weiwei Li <[e-mail]>
---
 target/riscv/cpu.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Alistair Francis May 10, 2022, 10:12 a.m. UTC | #1

On Tue, May 3, 2022 at 9:55 AM ~eopxd <[e-mail]> wrote:
>
> From: eopXD <[e-mail]>
>
> According to v-spec, tail agnostic behavior can be either kept as
> undisturbed or set elements' bits to all 1s. To distinguish the
> difference of tail policies, QEMU should be able to simulate the tail
> agnostic behavior as "set tail elements' bits to all 1s".
>
> There are multiple possibility for agnostic elements according to
> v-spec. The main intent of this patch-set tries to add option that
> can distinguish between tail policies. Setting agnostic elements to
> all 1s allows QEMU to express this.
>
> This commit adds option 'rvv_ta_all_1s' is added to enable the
> behavior, it is default as disabled.
>
> Signed-off-by: eop Chen <[e-mail]>
> Reviewed-by: Frank Chang <[e-mail]>
> Reviewed-by: Weiwei Li <[e-mail]>

Reviewed-by: Alistair Francis <[e-mail]>

Alistair

> ---
>  target/riscv/cpu.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index ddda4906ff..cd4cf4b41e 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -810,6 +810,7 @@ static Property riscv_cpu_properties[] = {
>      DEFINE_PROP_BOOL("x-aia", RISCVCPU, cfg.aia, false),
>
>      DEFINE_PROP_UINT64("resetvec", RISCVCPU, cfg.resetvec, DEFAULT_RSTVEC),
> +    DEFINE_PROP_BOOL("rvv_ta_all_1s", RISCVCPU, cfg.rvv_ta_all_1s, false),
>      DEFINE_PROP_END_OF_LIST(),
>  };
>
> --
> 2.34.2
>

Patch

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index ddda4906ff..cd4cf4b41e 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -810,6 +810,7 @@  static Property riscv_cpu_properties[] = {
     DEFINE_PROP_BOOL("x-aia", RISCVCPU, cfg.aia, false),
 
     DEFINE_PROP_UINT64("resetvec", RISCVCPU, cfg.resetvec, DEFAULT_RSTVEC),
+    DEFINE_PROP_BOOL("rvv_ta_all_1s", RISCVCPU, cfg.rvv_ta_all_1s, false),
     DEFINE_PROP_END_OF_LIST(),
 };