From a716763772b00fffab1b310d1dc3619e03675e73 Mon Sep 17 00:00:00 2001
From: Zhang Junyang <junyang@stu.pku.edu.cn>
Date: Fri, 4 Oct 2024 23:16:19 +0800
Subject: [PATCH] Remove the linkage feature usage for `ostd::main`

---
 kernel/src/lib.rs                                      |  1 -
 osdk/src/commands/new/kernel.template                  |  2 --
 .../work_in_workspace_templates/myos/src/lib.rs        |  1 -
 .../write_a_kernel_in_100_lines_templates/lib.rs       |  3 +--
 ostd/libs/ostd-macros/src/lib.rs                       | 10 +++-------
 ostd/src/panic.rs                                      |  2 +-
 6 files changed, 5 insertions(+), 14 deletions(-)

diff --git a/kernel/src/lib.rs b/kernel/src/lib.rs
index 25126a22..99bf8065 100644
--- a/kernel/src/lib.rs
+++ b/kernel/src/lib.rs
@@ -15,7 +15,6 @@
 #![feature(format_args_nl)]
 #![feature(int_roundings)]
 #![feature(let_chains)]
-#![feature(linkage)]
 #![feature(linked_list_remove)]
 #![feature(negative_impls)]
 #![feature(register_tool)]
diff --git a/osdk/src/commands/new/kernel.template b/osdk/src/commands/new/kernel.template
index c92050d1..bb5486ad 100644
--- a/osdk/src/commands/new/kernel.template
+++ b/osdk/src/commands/new/kernel.template
@@ -1,6 +1,4 @@
 #![no_std]
-// The feature `linkage` is required for `ostd::main` to work.
-#![feature(linkage)]
 #![deny(unsafe_code)]
 
 use ostd::prelude::*;
diff --git a/osdk/tests/examples_in_book/work_in_workspace_templates/myos/src/lib.rs b/osdk/tests/examples_in_book/work_in_workspace_templates/myos/src/lib.rs
index a5cd52cd..a8fc07f1 100644
--- a/osdk/tests/examples_in_book/work_in_workspace_templates/myos/src/lib.rs
+++ b/osdk/tests/examples_in_book/work_in_workspace_templates/myos/src/lib.rs
@@ -1,7 +1,6 @@
 // SPDX-License-Identifier: MPL-2.0
 
 #![no_std]
-#![feature(linkage)]
 #![deny(unsafe_code)]
 
 use ostd::prelude::*;
diff --git a/osdk/tests/examples_in_book/write_a_kernel_in_100_lines_templates/lib.rs b/osdk/tests/examples_in_book/write_a_kernel_in_100_lines_templates/lib.rs
index 06e0d728..1fc4bc79 100644
--- a/osdk/tests/examples_in_book/write_a_kernel_in_100_lines_templates/lib.rs
+++ b/osdk/tests/examples_in_book/write_a_kernel_in_100_lines_templates/lib.rs
@@ -1,8 +1,7 @@
 // SPDX-License-Identifier: MPL-2.0
 
 #![no_std]
-// The feature `linkage` is required for `ostd::main` to work.
-#![feature(linkage)]
+#![deny(unsafe_code)]
 
 extern crate alloc;
 
diff --git a/ostd/libs/ostd-macros/src/lib.rs b/ostd/libs/ostd-macros/src/lib.rs
index 7c5c57c9..91b031c0 100644
--- a/ostd/libs/ostd-macros/src/lib.rs
+++ b/ostd/libs/ostd-macros/src/lib.rs
@@ -13,7 +13,6 @@ use syn::{parse_macro_input, Expr, Ident, ItemFn};
 ///
 /// ```ignore
 /// #![no_std]
-/// #![feature(linkage)]
 ///
 /// use ostd::prelude::*;
 ///
@@ -28,13 +27,14 @@ pub fn main(_attr: TokenStream, item: TokenStream) -> TokenStream {
     let main_fn_name = &main_fn.sig.ident;
 
     quote!(
+        #[cfg(not(ktest))]
         #[no_mangle]
-        #[linkage = "weak"]
         extern "Rust" fn __ostd_main() -> ! {
             #main_fn_name();
             ostd::prelude::abort();
         }
 
+        #[allow(unused)]
         #main_fn
     )
     .into()
@@ -44,10 +44,6 @@ pub fn main(_attr: TokenStream, item: TokenStream) -> TokenStream {
 ///
 /// This macro is used for internal OSDK implementation. Do not use it
 /// directly.
-///
-/// It is a strong version of the `main` macro attribute. So if it exists (
-/// which means the unit test kernel is linked to perform testing), the actual
-/// kernel entry point will be replaced by this one.
 #[proc_macro_attribute]
 pub fn test_main(_attr: TokenStream, item: TokenStream) -> TokenStream {
     let main_fn = parse_macro_input!(item as ItemFn);
@@ -82,7 +78,7 @@ pub fn panic_handler(_attr: TokenStream, item: TokenStream) -> TokenStream {
             #handler_fn_name(info);
         }
 
-        #[cfg(not(ktest))]
+        #[allow(unused)]
         #handler_fn
     )
     .into()
diff --git a/ostd/src/panic.rs b/ostd/src/panic.rs
index a9ca9183..a25eec2d 100644
--- a/ostd/src/panic.rs
+++ b/ostd/src/panic.rs
@@ -25,7 +25,7 @@ use unwinding::abi::{
 ///
 /// The user can override it by defining their own panic handler with the macro
 /// `#[ostd::panic_handler]`.
-#[cfg(not(ktest))]
+#[linkage = "weak"]
 #[no_mangle]
 pub fn __ostd_panic_handler(info: &core::panic::PanicInfo) -> ! {
     let _irq_guard = crate::trap::disable_local();