Hi Atish,
Am Dienstag, 15. Februar 2022, 10:05:30 CET schrieb Atish Patra:
> Append the available ISA extensions to the "riscv,isa" string if it
> is enabled so that kernel can process it.
For people glancing at these patches, a bit more insight into
how the isa string comes together might be helpful.
See question below for the reason ;-)
> Signed-off-by: Atish Patra <ati...@rivosinc.com>
> ---
> target/riscv/cpu.c | 23 ++++++++++++++++++++++-
> 1 file changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index b0a40b83e7a8..c70260d0df15 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -34,6 +34,9 @@
>
> /* RISC-V CPU definitions */
>
> +/* This includes the null terminated character '\0' */
> +#define MAX_ISA_EXT_LEN 256
> +
> static const char riscv_exts[26] = "IEMAFDQCLBJTPVNSUHKORWXYZG";
>
> const char * const riscv_int_regnames[] = {
> @@ -881,10 +884,26 @@ static void riscv_cpu_class_init(ObjectClass *c, void
> *data)
> device_class_set_props(dc, riscv_cpu_properties);
> }
>
> +static void riscv_isa_string_ext(RISCVCPU *cpu, char *isa_str, int
> max_str_len)
> +{
> + int offset = strnlen(isa_str, max_str_len);
> +
> + if (cpu->cfg.ext_svpbmt) {
> + offset += snprintf(isa_str + offset, max_str_len, "_%s", "_svpbmt");
is a double-"__" the correct divider for isa extensions?
I.e. you have "_%s" as well as "_svpbmt" here, which creates a double
underscore in the ISA string.
> + }
> + if ((offset < max_str_len) && cpu->cfg.ext_svinval) {
> + offset += snprintf(isa_str + offset, max_str_len, "_%s", "_svinval");
> + }
> + if ((offset < max_str_len) && (cpu->cfg.ext_svnapot)) {
> + offset += snprintf(isa_str + offset, max_str_len, "_%s", "_svnapot");
> + }
> +}
> +
> 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_exts) +
> + MAX_ISA_EXT_LEN;
> 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++) {
> @@ -893,6 +912,8 @@ char *riscv_isa_string(RISCVCPU *cpu)
> }
> }
> *p = '\0';
blank line here?
> + riscv_isa_string_ext(cpu, isa_str, maxlen);
> +
> return isa_str;
> }
Heiko
