Fix linux-baremetal build

scripts/build.pl

@@ -219,7 +219,6 @@ if ( grep { $_ eq "fail" } @selected_targets ) {
 # Build everything
 # ========================================================================================= #
 
-# TODO: linux-baremetal target is broken
 system( "mkdir", "-p", "$local_builds_dir" );
 foreach my $experiment (@selected_experiments) {
     foreach my $target (@selected_targets) {

scripts/compile.pl

@@ -123,8 +123,7 @@ my @cross_ldflags_base = (
 my @linux_ldflags_base     = ( '-Wl,--build-id=none', '-m32', '-lm' );
 my @baremetal_ldflags_base = (
     '-Wl,--build-id=none', '-static', '-nostdlib', '-m32',
-    '-lc',                 '-lgcc',   '-lm',       '--entry',
-    'main'
+    '-lc', '-lgcc', '-lm'
 );
 my @cross_ldflags_nowasm = (
     '-Wl,--build-id=none', '-static', '-nostdlib', '-m32',
@@ -199,7 +198,8 @@ sub build {
         die "Unknown mode '$mode'; expected: aot, interp, c\n";
     }
 
-    build_iso( $module, $bd );
+    build_iso( $module, $bd )
+      if $target eq 'fail' || $target eq 'linux-baremetal';
 }
 
 # ========================================================================================= #
@@ -373,8 +373,9 @@ sub compile_wasm_host {
 sub compile_c_module {
     my ( $module, $bd, $target ) = @_;
     my ( $cc, @flags ) =
-        ( $target eq 'linux' )
-      ? ( $linux_cc, @linux_cflags, '-DTARGET_LINUX' )
+        ( $target eq 'linux' ) ? ( $linux_cc, @linux_cflags, '-DTARGET_LINUX' )
+      : ( $target eq 'linux-baremetal' )
+      ? ( $cross_cc, @linux_baremetal_cflags, '-DTARGET_LINUX_BAREMETAL' )
       : ( $cross_cc, @cross_cflags, '-DTARGET_FAIL' );
 
     if ( Util::module_is_tacle($module) ) {
@@ -404,8 +405,9 @@ sub compile_c_module {
 sub compile_c_host {
     my ( $module, $bd, $target ) = @_;
     my ( $cc, @flags ) =
-        ( $target eq 'linux' )
-      ? ( $linux_cc, @linux_cflags, '-DTARGET_LINUX' )
+        ( $target eq 'linux' ) ? ( $linux_cc, @linux_cflags, '-DTARGET_LINUX' )
+      : ( $target eq 'linux-baremetal' )
+      ? ( $cross_cc, @linux_baremetal_cflags, '-DTARGET_LINUX_BAREMETAL' )
       : ( $cross_cc, @cross_cflags, '-DTARGET_FAIL' );
     Util::run( $cc, @flags, '-c', 'targets/c-host/c_host.c', '-o',
         "$bd/c_host.o" );
@@ -414,7 +416,7 @@ sub compile_c_host {
 
 sub compile_startup {
     my ( $module, $bd, $target ) = @_;
-    return unless $target eq 'fail';
+    return unless $target eq 'fail' || $target eq 'linux-baremetal';
     Util::run( $cross_cc, 'targets/startup.s', '-I./targets/wasm-host',
         @cross_cflags, '-c', '-o', "$bd/startup.o" );
 }
@@ -450,8 +452,13 @@ sub link_wasm {
             @linux_ldflags_base, '-o', "$bd/system.elf" );
     }
     elsif ( $target eq 'linux-baremetal' ) {
-        Util::run( $cross_cc, "$bd/system.o", "$bd/syscalls.o",
-            "$bd/libiwasm.a", @baremetal_ldflags_base, '-o', "$bd/system.elf" );
+        Util::run(
+            $cross_cc,           '-Wl,-T',
+            'targets/linker.ld', "$bd/system.o",
+            "$bd/startup.o",     "$bd/syscalls.o",
+            "$bd/libiwasm.a",    @baremetal_ldflags_base,
+            '-o',                "$bd/system.elf"
+        );
     }
     else {
         die "Unknown target '$target'\n";
@@ -476,6 +483,16 @@ sub link_c {
         Util::run( $linux_cc, "$bd/c_host.o", "$bd/c_module.o", @tacle_objs,
             @linux_ldflags_nowasm, '-o', "$bd/system.elf" );
     }
+    elsif ( $target eq 'linux-baremetal' ) {
+        Util::run(
+            $cross_cc,               '-Wl,-T',
+            'targets/linker.ld',     "$bd/c_host.o",
+            "$bd/startup.o",         "$bd/syscalls.o",
+            "$bd/c_module.o",        @tacle_objs,
+            @baremetal_ldflags_base, '-o',
+            "$bd/system.elf"
+        );
+    }
     else {
         die "C mode is not supported for target '$target'\n";
     }

targets/lib.h

@@ -31,11 +31,11 @@
 #endif
 
 #ifdef TARGET_LINUX_BAREMETAL
-#define MAIN int main(int argc, char *argv[])
+#define MAIN void os_main(void)
 #define PRINT(fmt, ...)
 #define PRINT_ERROR(fmt, ...)
 #define PRINT_SUCCESS(fmt, ...)
-#define RET(val) return val
+#define RET(val) return
 #endif
 
 #ifdef TARGET_LINUX