Add more from the std

.cargo/config.toml

@@ -3,10 +3,9 @@ target = "riscv64.json"
 
 [unstable]
 json-target-spec = true
-# build-std = []
-# build-std-features = ["compiler-builtins-mem"]
 
 [target.riscv64]
 rustflags = [
   "-C", "link-arg=-Tilm.ld",
+  "--sysroot", "sysroot"
 ]