First successful rust library call

Makefile

@@ -3,7 +3,6 @@ U=user
 R=rust
 
 RTARGET = riscv64gc-unknown-none-elf
-RENV = debug
 
 OBJS = \
   $K/entry.o \
@@ -35,7 +34,7 @@ OBJS = \
   $K/virtio_disk.o
 
 RLIBS = \
-	$R/foo/target/$(RTARGET)/$(RENV)/libfoo.rlib
+	$R/foo/target/$(RTARGET)/release/libfoo.a
 
 # riscv64-unknown-elf- or riscv64-linux-gnu-
 # perhaps in /opt/riscv/bin
@@ -146,7 +145,7 @@ fs.img: mkfs/mkfs README $(UPROGS)
 -include kernel/*.d user/*.d
 
 rustlibs:
-	cargo build --manifest-path $R/foo/Cargo.toml
+	cargo build -r --manifest-path $R/foo/Cargo.toml
 
 clean: 
 	rm -f *.tex *.dvi *.idx *.aux *.log *.ind *.ilg \

kernel/main.c

@@ -3,6 +3,9 @@
 #include "memlayout.h"
 #include "riscv.h"
 #include "defs.h"
+#include <stdint.h>
+
+extern int32_t add(int32_t right, int32_t left);
 
 volatile static int started = 0;
 
@@ -13,7 +16,8 @@ void main() {
 		printfinit();
 		printf("\n");
 		printf("xv6 kernel is booting\n");
-		// printf("rustlib: add(1, 2) = %d\n", add(1, 2));
+		printf("\n");
+		printf("rust library call: add(1, 2) = %d\n", add(1, 2));
 		printf("\n");
 		kinit();			// physical page allocator
 		kvminit();			// create kernel page table

rust/foo/Cargo.toml

@@ -3,6 +3,12 @@ name = "foo"
 version = "0.1.0"
 edition = "2021"
 
+[lib]
+crate-type = [ "staticlib" ]
+
+[profile.release]
+panic = "abort"
+
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]

rust/foo/src/lib.rs

@@ -1,5 +1,13 @@
 #![no_std]
+#![crate_type = "staticlib"]
 
-pub fn add(left: usize, right: usize) -> usize {
+#[no_mangle]
-	left + right + 5
+pub extern "C" fn add(left: i32, right: i32) -> i32 {
+	left + right
+}
+
+#[panic_handler]
+#[no_mangle]
+fn panic(_info: &core::panic::PanicInfo) -> ! {
+	loop {}
 }