Re: [PATCH] target/riscv: Add Zihintntl extension ISA string to DTS

[Alistair Francis]

On Tue, Jul 4, 2023 at 6:42 PM Jason Chien <jason.chien@sifive.com> wrote:
>
> RVA23 Profiles states:
> The RVA23 profiles are intended to be used for 64-bit application
> processors that will run rich OS stacks from standard binary OS
> distributions and with a substantial number of third-party binary user
> applications that will be supported over a considerable length of time
> in the field.
>
> The chapter 4 of the unprivileged spec introduces the Zihintntl extension
> and Zihintntl is a mandatory extension presented in RVA23 Profiles, whose
> purpose is to enable application and operating system portability across
> different implementations. Thus the DTS should contain the Zihintntl ISA
> string in order to pass to software.
>
> The unprivileged spec states:
> Like any HINTs, these instructions may be freely ignored. Hence, although
> they are described in terms of cache-based memory hierarchies, they do not
> mandate the provision of caches.
>
> These instructions are encoded with used opcode, e.g. ADD x0, x0, x2, which
> QEMU already supports, and QEMU does not emulate cache. Therefore these
> instructions can be considered as a no-op, and we only need to add a new
> property for the Zihintntl extension.
>
> Signed-off-by: Jason Chien <jason.chien@sifive.com>

Thanks for the patch, do you mind rebasing it on
https://github.com/alistair23/qemu/tree/riscv-to-apply.next

Alistair

> ---
>  target/riscv/cpu.c     | 2 ++
>  target/riscv/cpu_cfg.h | 1 +
>  2 files changed, 3 insertions(+)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 881bddf393..6fd21466a4 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -81,6 +81,7 @@ static const struct isa_ext_data isa_edata_arr[] = {
>      ISA_EXT_DATA_ENTRY(zicond, PRIV_VERSION_1_12_0, ext_zicond),
>      ISA_EXT_DATA_ENTRY(zicsr, PRIV_VERSION_1_10_0, ext_icsr),
>      ISA_EXT_DATA_ENTRY(zifencei, PRIV_VERSION_1_10_0, ext_ifencei),
> +    ISA_EXT_DATA_ENTRY(zihintntl, PRIV_VERSION_1_10_0, ext_zihintntl),
>      ISA_EXT_DATA_ENTRY(zihintpause, PRIV_VERSION_1_10_0, ext_zihintpause),
>      ISA_EXT_DATA_ENTRY(zawrs, PRIV_VERSION_1_12_0, ext_zawrs),
>      ISA_EXT_DATA_ENTRY(zfh, PRIV_VERSION_1_11_0, ext_zfh),
> @@ -1598,6 +1599,7 @@ static Property riscv_cpu_extensions[] = {
>      DEFINE_PROP_BOOL("sscofpmf", RISCVCPU, cfg.ext_sscofpmf, false),
>      DEFINE_PROP_BOOL("Zifencei", RISCVCPU, cfg.ext_ifencei, true),
>      DEFINE_PROP_BOOL("Zicsr", RISCVCPU, cfg.ext_icsr, true),
> +    DEFINE_PROP_BOOL("Zihintntl", RISCVCPU, cfg.ext_zihintntl, true),
>      DEFINE_PROP_BOOL("Zihintpause", RISCVCPU, cfg.ext_zihintpause, true),
>      DEFINE_PROP_BOOL("Zawrs", RISCVCPU, cfg.ext_zawrs, true),
>      DEFINE_PROP_BOOL("Zfh", RISCVCPU, cfg.ext_zfh, false),
> diff --git a/target/riscv/cpu_cfg.h b/target/riscv/cpu_cfg.h
> index c4a627d335..c7da2facef 100644
> --- a/target/riscv/cpu_cfg.h
> +++ b/target/riscv/cpu_cfg.h
> @@ -66,6 +66,7 @@ struct RISCVCPUConfig {
>      bool ext_icbom;
>      bool ext_icboz;
>      bool ext_zicond;
> +    bool ext_zihintntl;
>      bool ext_zihintpause;
>      bool ext_smstateen;
>      bool ext_sstc;
> --
> 2.17.1
>
>