add support for linux_riscv64 and freestanding_riscv64

core/sys/info/cpu_linux_riscv64.odin

@@ -0,0 +1,46 @@
+//+build riscv64
+//+build linux
+package sysinfo
+
+import "base:intrinsics"
+
+import "core:sys/linux"
+
+@(init, private)
+init_cpu_features :: proc() {
+	fd, err := linux.open("/proc/self/auxv", {})
+	if err != .NONE { return }
+	defer linux.close(fd)
+
+	// This is probably enough right?
+	buf: [4096]byte
+	n, rerr := linux.read(fd, buf[:])
+	if rerr != .NONE || n == 0 { return }
+
+	ulong     :: u64
+	AT_HWCAP  :: 16
+
+	// TODO: using these we could get more information than just the basics.
+	// AT_HWCAP2 :: 26
+	// AT_HWCAP3 :: 29
+	// AT_HWCAP4 :: 30
+
+	auxv := buf[:n]
+	for len(auxv) >= size_of(ulong)*2 {
+		key := intrinsics.unaligned_load((^ulong)(&auxv[0]))
+		val := intrinsics.unaligned_load((^ulong)(&auxv[size_of(ulong)]))
+		auxv = auxv[2*size_of(ulong):]
+
+		if key != AT_HWCAP {
+			continue
+		}
+
+		cpu_features = transmute(CPU_Features)(val)
+		break
+	}
+}
+
+@(init, private)
+init_cpu_name :: proc() {
+	cpu_name = "RISCV64"
+}