build: fix UM build

build.zig

@@ -225,6 +225,8 @@ fn addKernel(b: *std.Build, plat: config.Platform, optimize: std.builtin.Optimiz
             .optimize = optimize,
         });
 
+        translate_c.addIncludePath(.{ .cwd_relative = "/usr/include" });
+
         kernel.root_module.addImport("c", translate_c.createModule());
         kernel.linker_script = b.path("build/linker-scripts/uml.lds");
         kernel.root_module.link_libc = true;

src/mm/init.zig

@@ -91,7 +91,7 @@ fn map_kernel(boot_info: *pl.BootInfo) void {
 
 pub fn init(boot_info: *pl.BootInfo) linksection(r.init) void {
     mi.phys.init(boot_info);
-    if (!@hasDecl(config, "CONFIG_ARCH_UM")) {
+    if (config.arch != .um) {
         map_kernel(boot_info);
     }
     mi.kernel_pmap.activate();

src/platform/um/c.h

@@ -1,5 +1,5 @@
 #define _GNU_SOURCE 1
-#include <SDL.h>
+#include <SDL2/SDL.h>
 #include <pthread.h>
 #include <sched.h>
 #include <signal.h>

src/root.zig

@@ -55,7 +55,7 @@ pub const std_options = std.Options{
 
 pub const panic = std.debug.FullPanic(ke.panic);
 
-pub const main = if (@hasDecl(config, "CONFIG_ARCH_UM")) pl.impl.entry.main else undefined;
+pub const main = if (config.arch == .um) pl.impl.entry.main else undefined;
 
 comptime {
     // Ensure the entry point is linked in.