Bringup loader config block parsing

Not tested yet

crt0/switch_crt0.s

@@ -12,7 +12,8 @@ startup:
     bl   +4
     sub  x28, x30, #0x84
 
-    // save main thread handle
+    // save context ptr and main thread handle
+    mov  x26, x0
     mov  x27, x1
 
     // clear .bss
@@ -36,7 +37,8 @@ bss_loop:
     bl   __nx_dynamic
 
     // initialize system
-    mov  x0, x27
+    mov  x0, x26
+    mov  x1, x27
     bl   __libnx_init
 
     // call entrypoint

nx/include/switch.h

@@ -44,6 +44,8 @@ extern "C" {
 #include <switch/gfx/nvioctl.h>
 #include <switch/gfx/nvgfx.h>
 
+#include <switch/runtime/env.h>
+
 #include <switch/runtime/util/utf.h>
 
 #include <switch/runtime/devices/console.h>

nx/include/switch/runtime/env.h

@@ -0,0 +1,5 @@
+// Copyright 2018 plutoo
+
+void   envParse(void* ctx, Handle main_thread);
+Handle envGetMainThreadHandle(void);
+bool   envIsNso(void);

nx/source/runtime/env.c

@@ -0,0 +1,91 @@
+// Copyright 2018 plutoo
+#include <switch.h>
+
+static bool   g_isNso = false;
+static Handle g_mainThreadHandle = INVALID_HANDLE;
+static void*  g_loaderRetAddr = NULL;
+static void*  g_overrideHeapAddr = NULL;
+static u64    g_overrideHeapSize = 0;
+
+typedef struct {
+    u32 Key;
+    u32 Flags;
+    u64 Value[2];
+} ConfigEntry;
+
+enum {
+    EntryType_EndOfList=0,
+    EntryType_MainThreadHandle=1,
+    EntryType_LoaderReturnAddr=2,
+    EntryType_OverrideHeap=3,
+    EntryType_OverrideService=4,
+    EntryType_Argv=5,
+    EntryType_SyscallAvailableHint=6,
+    EntryType_AppletType=7
+};
+
+void envParse(void* ctx, Handle main_thread)
+{
+    if (main_thread != INVALID_HANDLE)
+    {
+        g_mainThreadHandle = main_thread;
+        g_isNso = true;
+        return;
+    }
+
+    ConfigEntry* ent = ctx;
+
+    while (ent->Key != EntryType_EndOfList)
+    {
+        switch (ent->Key)
+        {
+        case EntryType_MainThreadHandle:
+            g_mainThreadHandle = ent->Value[0];
+            break;
+
+        case EntryType_LoaderReturnAddr:
+            g_loaderRetAddr = (void*) ent->Value[0];
+            break;
+
+        case EntryType_OverrideHeap:
+            g_overrideHeapAddr = (void*) ent->Value[0];
+            g_overrideHeapSize = ent->Value[1];
+            break;
+
+        case EntryType_OverrideService:
+            // TODO
+            break;
+
+        case EntryType_Argv:
+            // TODO
+            break;
+
+        case EntryType_SyscallAvailableHint:
+            // TODO
+            break;
+
+        case EntryType_AppletType:
+            // TODO
+            break;
+
+        default:
+            // TODO
+            break;
+        }
+
+        ent++;
+    }
+
+}
+
+Handle envGetMainThreadHandle(void) {
+    if (g_mainThreadHandle != INVALID_HANDLE) {
+        return g_mainThreadHandle;
+    }
+
+    fatalSimple(1);
+}
+
+bool envIsNso(void) {
+    return g_isNso;
+}

nx/source/runtime/init.c

@@ -3,7 +3,7 @@
 void __nx_exit(int rc);
 
 void virtmemSetup(void);
-void newlibSetup(Handle main_thread);
+void newlibSetup(void);
 
 void __system_initArgv(void);
 
@@ -53,12 +53,13 @@ void __attribute__((weak)) __appExit(void)
     smExit();
 }
 
-void __attribute__((weak)) __libnx_init(Handle main_thread)
+void __attribute__((weak)) __libnx_init(void* ctx, Handle main_thread)
 {
     // Called by crt0.
 
     // Libnx initialization goes here.
-    newlibSetup(main_thread);
+    envParse(ctx, main_thread);
+    newlibSetup();
     virtmemSetup();
     __libnx_initheap();
 

nx/source/runtime/newlib.c

@@ -18,7 +18,7 @@ static struct _reent* __libnx_get_reent(void) {
     return tv->reent;
 }
 
-void newlibSetup(Handle main_thread) {
+void newlibSetup() {
     // Register newlib syscalls
     __syscalls.exit     = __libnx_exit;
     __syscalls.getreent = __libnx_get_reent;
@@ -39,7 +39,7 @@ void newlibSetup(Handle main_thread) {
     tv->thread_ptr = NULL;
     tv->reent      = _impure_ptr;
     tv->tls_tp     = __tls_start-2*sizeof(void*); // subtract size of Thread Control Block (TCB)
-    tv->handle     = main_thread;
+    tv->handle     = envGetMainThreadHandle();
 
     u32 tls_size = __tdata_lma_end - __tdata_lma;
     if (tls_size)