The Linux kernel parses the ISA extensions from "riscv,isa" DT
property. It used to parse only the single letter base extensions
until now. A generic ISA extension parsing framework was proposed[1]
recently that can parse multi-letter ISA extensions as well.
Generate the extended ISA string by appending the available ISA extensions
to the "riscv,isa" string if it is enabled so that kernel can process it.
[1] https://lkml.org/lkml/2022/2/15/263
Suggested-by: Heiko Stubner <heiko@sntech.de>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
---
Changes from v2->v3:
1. Used g_strconcat to replace snprintf & a max isa string length as
suggested by Anup.
2. I have not included the Tested-by Tag from Heiko because the
implementation changed from v2 to v3.
Changes from v1->v2:
1. Improved the code redability by using arrays instead of individual check
---
target/riscv/cpu.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index b0a40b83e7a8..2c7ff6ef555a 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -34,6 +34,12 @@
/* RISC-V CPU definitions */
+/* This includes the null terminated character '\0' */
+struct isa_ext_data {
+ const char *name;
+ bool enabled;
+};
+
static const char riscv_exts[26] = "IEMAFDQCLBJTPVNSUHKORWXYZG";
const char * const riscv_int_regnames[] = {
@@ -881,6 +887,28 @@ 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)
+{
+ char *old = *isa_str;
+ char *new = *isa_str;
+ int i;
+ struct isa_ext_data isa_edata_arr[] = {
+ { "svpbmt", cpu->cfg.ext_svpbmt },
+ { "svinval", cpu->cfg.ext_svinval },
+ { "svnapot", cpu->cfg.ext_svnapot },
We still have other sub-extensions, e.g. Zfh, Zba, Zbb, Zbc, Zbs... etc.
Do you mind adding them as well?
Also, I think the order of ISA strings should be alphabetical as described:
Regards,
Frank Chang
+ };
+
+ for (i = 0; i < ARRAY_SIZE(isa_edata_arr); i++) {
+ if (isa_edata_arr[i].enabled) {
+ new = g_strconcat(old, "_", isa_edata_arr[i].name, NULL);
+ g_free(old);
+ old = new;
+ }
+ }
+
+ *isa_str = new;
+}
+
char *riscv_isa_string(RISCVCPU *cpu)
{
int i;
@@ -893,6 +921,7 @@ char *riscv_isa_string(RISCVCPU *cpu)
}
}
*p = '\0';
+ riscv_isa_string_ext(cpu, &isa_str, maxlen);
return isa_str;
}
--
2.30.2