On Mon, Mar 28, 2022 at 11:11 PM Tsukasa OI
<research_tra...@irq.a4lg.com> wrote:
>
> Some bits in RISC-V `misa' CSR should not be reflected in the ISA
> string. For instance, `S' and `U' (represents existence of supervisor
> and user mode, respectively) in `misa' CSR must not be copied since
> neither `S' nor `U' are valid single-letter extensions.
>
> This commit also removes all reserved/dropped single-letter "extensions"
> from the list.
>
> - "B": Not going to be a single-letter extension (misa.B is reserved).
> - "J": Not going to be a single-letter extension (misa.J is reserved).
> - "K": Not going to be a single-letter extension (misa.K is reserved).
Interesting, these are still listed in "ISA Extension Naming Conventions".
They can just be re-added if they are used in the future.
Reviewed-by: Alistair Francis <alistair.fran...@wdc.com>
Alistair
> - "L": Dropped.
> - "N": Dropped.
> - "T": Dropped.
>
> It also clarifies that the variable `riscv_single_letter_exts' is a
> single-letter extension order list.
>
> Signed-off-by: Tsukasa OI <research_tra...@irq.a4lg.com>
> ---
> target/riscv/cpu.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index ddda4906ff..1f68c696eb 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -34,7 +34,7 @@
>
> /* RISC-V CPU definitions */
>
> -static const char riscv_exts[26] = "IEMAFDQCLBJTPVNSUHKORWXYZG";
> +static const char riscv_single_letter_exts[] = "IEMAFDQCPVH";
>
> const char * const riscv_int_regnames[] = {
> "x0/zero", "x1/ra", "x2/sp", "x3/gp", "x4/tp", "x5/t0", "x6/t1",
> @@ -901,12 +901,12 @@ static void riscv_cpu_class_init(ObjectClass *c, void
> *data)
> char *riscv_isa_string(RISCVCPU *cpu)
> {
> int i;
> - const size_t maxlen = sizeof("rv128") + sizeof(riscv_exts) + 1;
> + const size_t maxlen = sizeof("rv128") + sizeof(riscv_single_letter_exts);
> char *isa_str = g_new(char, maxlen);
> char *p = isa_str + snprintf(isa_str, maxlen, "rv%d", TARGET_LONG_BITS);
> - for (i = 0; i < sizeof(riscv_exts); i++) {
> - if (cpu->env.misa_ext & RV(riscv_exts[i])) {
> - *p++ = qemu_tolower(riscv_exts[i]);
> + for (i = 0; i < sizeof(riscv_single_letter_exts) - 1; i++) {
> + if (cpu->env.misa_ext & RV(riscv_single_letter_exts[i])) {
> + *p++ = qemu_tolower(riscv_single_letter_exts[i]);
> }
> }
> *p = '\0';
> --
> 2.32.0
>
