Re: [PATCH v5 2/3] target/riscv: Expose sdtrig ISA extension

[Andrew Jones]

On Wed, Mar 13, 2024 at 11:50:08PM +0530, Himanshu Chauhan wrote:
> This patch adds "sdtrig" in the ISA string when sdtrig extension is enabled.
> The sdtrig extension may or may not be implemented in a system. Therefore, the
>            -cpu rv64,sdtrig=<true/false>
> option can be used to dynamically turn sdtrig extension on or off.
> 
> Since, the sdtrig ISA extension is a superset of debug specification, disable
> the debug property when sdtrig is enabled. A warning is printed when this is
> done.
> 
> By default, the sdtrig extension is disabled and debug property enabled as 
> usual.
> 
> Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
> ---
>  target/riscv/cpu.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 2602aae9f5..e0710010f5 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -175,6 +175,7 @@ const RISCVIsaExtData isa_edata_arr[] = {
>      ISA_EXT_DATA_ENTRY(zvkt, PRIV_VERSION_1_12_0, ext_zvkt),
>      ISA_EXT_DATA_ENTRY(zhinx, PRIV_VERSION_1_12_0, ext_zhinx),
>      ISA_EXT_DATA_ENTRY(zhinxmin, PRIV_VERSION_1_12_0, ext_zhinxmin),
> +    ISA_EXT_DATA_ENTRY(sdtrig, PRIV_VERSION_1_12_0, ext_sdtrig),
>      ISA_EXT_DATA_ENTRY(smaia, PRIV_VERSION_1_12_0, ext_smaia),
>      ISA_EXT_DATA_ENTRY(smepmp, PRIV_VERSION_1_12_0, ext_smepmp),
>      ISA_EXT_DATA_ENTRY(smstateen, PRIV_VERSION_1_12_0, ext_smstateen),
> @@ -1008,6 +1009,10 @@ static void riscv_cpu_reset_hold(Object *obj)
>      set_default_nan_mode(1, &env->fp_status);
>  
>  #ifndef CONFIG_USER_ONLY
> +    if (!cpu->cfg.debug && cpu->cfg.ext_sdtrig) {
> +         cpu->cfg.debug = 1;

nit: '= true'

I also wonder if we need a warning here that says something like
"reenabling 'debug' since 'sdtrig' is enabled...", since the only way we'd
get here is if the user did 'debug=off,sdtrig=on'. But, I think I might be
OK with just silently ignoring that 'debug=off' too.

Thanks,
drew

> +    }
> +
>      if (cpu->cfg.debug || cpu->cfg.ext_sdtrig) {
>          riscv_trigger_reset_hold(env);
>      }
> @@ -1480,6 +1485,7 @@ const RISCVCPUMultiExtConfig riscv_cpu_extensions[] = {
>      MULTI_EXT_CFG_BOOL("zvfhmin", ext_zvfhmin, false),
>      MULTI_EXT_CFG_BOOL("sstc", ext_sstc, true),
>  
> +    MULTI_EXT_CFG_BOOL("sdtrig", ext_sdtrig, false),
>      MULTI_EXT_CFG_BOOL("smaia", ext_smaia, false),
>      MULTI_EXT_CFG_BOOL("smepmp", ext_smepmp, false),
>      MULTI_EXT_CFG_BOOL("smstateen", ext_smstateen, false),
> -- 
> 2.34.1
> 
>