diff --git a/compiler/GHC/Runtime/Heap/Layout.hs b/compiler/GHC/Runtime/Heap/Layout.hs
index 73e2ff9e410a..e0956185a59a 100644
--- a/compiler/GHC/Runtime/Heap/Layout.hs
+++ b/compiler/GHC/Runtime/Heap/Layout.hs
@@ -438,8 +438,8 @@ cardTableSizeW platform elems =
 -----------------------------------------------------------------------------
 -- deriving the RTS closure type from an SMRep
 
-#include "ClosureTypes.h"
-#include "FunTypes.h"
+#include "rts/storage/ClosureTypes.h"
+#include "rts/storage/FunTypes.h"
 -- Defines CONSTR, CONSTR_1_0 etc
 
 -- | Derives the RTS closure type from an 'SMRep'
diff --git a/compiler/GHC/StgToCmm/Layout.hs b/compiler/GHC/StgToCmm/Layout.hs
index 2f81200a2891..b93dc1854084 100644
--- a/compiler/GHC/StgToCmm/Layout.hs
+++ b/compiler/GHC/StgToCmm/Layout.hs
@@ -549,7 +549,7 @@ mkVirtConstrSizes profile field_reps
 -------------------------------------------------------------------------
 
 -- bring in ARG_P, ARG_N, etc.
-#include "FunTypes.h"
+#include "rts/storage/FunTypes.h"
 
 mkArgDescr :: Platform -> [Id] -> ArgDescr
 mkArgDescr platform args
diff --git a/compiler/GHC/StgToCmm/TagCheck.hs b/compiler/GHC/StgToCmm/TagCheck.hs
index 5b3cf2e7e1e8..18fd617c0000 100644
--- a/compiler/GHC/StgToCmm/TagCheck.hs
+++ b/compiler/GHC/StgToCmm/TagCheck.hs
@@ -12,7 +12,7 @@ module GHC.StgToCmm.TagCheck
   ( emitTagAssertion, emitArgTagCheck, checkArg, whenCheckTags,
     checkArgStatic, checkFunctionArgTags,checkConArgsStatic,checkConArgsDyn) where
 
-#include "ClosureTypes.h"
+#include "rts/storage/ClosureTypes.h"
 
 import GHC.Prelude
 
diff --git a/rts-fs/README b/rts-fs/README
new file mode 100644
index 000000000000..446f95e9eceb
--- /dev/null
+++ b/rts-fs/README
@@ -0,0 +1,2 @@
+This "fs" library, used by various ghc utilities is used to share some common
+I/O filesystem functions with different packages.
diff --git a/rts-fs/fs.c b/rts-fs/fs.c
new file mode 100644
index 000000000000..d64094cae158
--- /dev/null
+++ b/rts-fs/fs.c
@@ -0,0 +1,590 @@
+/* -----------------------------------------------------------------------------
+ *
+ * (c) Tamar Christina 2018-2019
+ *
+ * Windows I/O routines for file opening.
+ *
+ * NOTE: Only modify this file in utils/fs/ and rerun configure. Do not edit
+ *       this file in any other directory as it will be overwritten.
+ *
+ * ---------------------------------------------------------------------------*/
+#include "fs.h"
+#include <stdio.h>
+
+#if defined(_WIN32)
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+#include <windows.h>
+#include <io.h>
+#include <fcntl.h>
+#include <wchar.h>
+#include <share.h>
+#include <errno.h>
+
+/* Duplicate a string, but in wide form. The caller is responsible for freeing
+   the result. */
+static wchar_t* FS(to_wide) (const char *path) {
+  size_t len = mbstowcs (NULL, path, 0);
+  wchar_t *w_path = malloc (sizeof (wchar_t) * (len + 1));
+  mbstowcs (w_path, path, len);
+  w_path[len] = L'\0';
+  return w_path;
+}
+
+/* This function converts Windows paths between namespaces. More specifically
+   It converts an explorer style path into a NT or Win32 namespace.
+   This has several caveats but they are caveats that are native to Windows and
+   not POSIX. See
+   https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247.aspx.
+   Anything else such as raw device paths we leave untouched.  The main benefit
+   of doing any of this is that we can break the MAX_PATH restriction and also
+   access raw handles that we couldn't before.
+
+   The resulting string is dynamically allocated and so callers are expected to
+   free this string.  */
+wchar_t* FS(create_device_name) (const wchar_t* filename) {
+  const wchar_t* win32_dev_namespace  = L"\\\\.\\";
+  const wchar_t* win32_file_namespace = L"\\\\?\\";
+  const wchar_t* nt_device_namespace  = L"\\Device\\";
+  const wchar_t* unc_prefix           = L"UNC\\";
+  const wchar_t* network_share        = L"\\\\";
+
+  wchar_t* result = _wcsdup (filename);
+  wchar_t ns[10] = {0};
+
+  /* If the file is already in a native namespace don't change it.  */
+  if (   wcsncmp (win32_dev_namespace , filename, 4) == 0
+      || wcsncmp (win32_file_namespace, filename, 4) == 0
+      || wcsncmp (nt_device_namespace , filename, 8) == 0)
+    return result;
+
+  /* Since we're using the lower level APIs we must normalize slashes now.  The
+     Win32 API layer will no longer convert '/' into '\\' for us.  */
+  for (size_t i = 0; i < wcslen (result); i++)
+    {
+      if (result[i] == L'/')
+        result[i] = L'\\';
+    }
+
+  /* We need to expand dos short paths as well.  */
+  DWORD nResult = GetLongPathNameW (result, NULL, 0) + 1;
+  wchar_t* temp = NULL;
+  if (nResult > 1)
+    {
+      temp = _wcsdup (result);
+      free (result);
+      result = malloc (nResult * sizeof (wchar_t));
+      if (GetLongPathNameW (temp, result, nResult) == 0)
+        {
+          result = memcpy (result, temp, wcslen (temp));
+          goto cleanup;
+        }
+      free (temp);
+    }
+
+  /* Now resolve any . and .. in the path or subsequent API calls may fail since
+     Win32 will no longer resolve them.  */
+  nResult = GetFullPathNameW (result, 0, NULL, NULL) + 1;
+  temp = _wcsdup (result);
+  free (result);
+  result = malloc (nResult * sizeof (wchar_t));
+  if (GetFullPathNameW (temp, nResult, result, NULL) == 0)
+    {
+      result = memcpy (result, temp, wcslen (temp));
+      goto cleanup;
+    }
+
+  free (temp);
+
+  int startOffset = 0;
+  /* When remapping a network share, \\foo needs to become
+     \\?\UNC\foo and not \\?\\UNC\\foo which is an invalid path.  */
+  if (wcsncmp (network_share, result, 2) == 0)
+    {
+      if (swprintf (ns, 10, L"%ls%ls", win32_file_namespace, unc_prefix) <= 0)
+        {
+          goto cleanup;
+        }
+      startOffset = 2;
+    }
+  else if (swprintf (ns, 10, L"%ls", win32_file_namespace) <= 0)
+    {
+      goto cleanup;
+    }
+
+  /* Create new string.  */
+  int bLen = wcslen (result) + wcslen (ns) + 1 - startOffset;
+  temp = _wcsdup (result + startOffset);
+  free (result);
+  result = malloc (bLen * sizeof (wchar_t));
+  if (swprintf (result, bLen, L"%ls%ls", ns, temp) <= 0)
+    {
+      goto cleanup;
+    }
+
+  free (temp);
+
+  return result;
+
+cleanup:
+  free (temp);
+  free (result);
+  return NULL;
+}
+
+static int setErrNoFromWin32Error (void);
+/* Sets errno to the right error value and returns -1 to indicate the failure.
+   This function should only be called when the creation of the fd actually
+   failed and you want to return -1 for the fd.  */
+static
+int setErrNoFromWin32Error (void) {
+  switch (GetLastError()) {
+    case ERROR_SUCCESS:
+      errno = 0;
+      break;
+    case ERROR_ACCESS_DENIED:
+    case ERROR_FILE_READ_ONLY:
+      errno = EACCES;
+      break;
+    case ERROR_FILE_NOT_FOUND:
+    case ERROR_PATH_NOT_FOUND:
+      errno = ENOENT;
+      break;
+    case ERROR_FILE_EXISTS:
+      errno = EEXIST;
+      break;
+    case ERROR_NOT_ENOUGH_MEMORY:
+    case ERROR_OUTOFMEMORY:
+      errno = ENOMEM;
+      break;
+    case ERROR_INVALID_HANDLE:
+      errno = EBADF;
+      break;
+    case ERROR_INVALID_FUNCTION:
+      errno = EFAULT;
+      break;
+    default:
+      errno = EINVAL;
+      break;
+  }
+  return -1;
+}
+
+
+#define HAS_FLAG(a,b) (((a) & (b)) == (b))
+
+int FS(swopen) (const wchar_t* filename, int oflag, int shflag, int pmode)
+{
+  /* Construct access mode.  */
+  /* https://docs.microsoft.com/en-us/windows/win32/fileio/file-access-rights-constants  */
+  DWORD dwDesiredAccess = 0;
+  if (HAS_FLAG (oflag, _O_RDONLY))
+    dwDesiredAccess |= GENERIC_READ;
+  if (HAS_FLAG (oflag, _O_RDWR))
+    dwDesiredAccess |= GENERIC_WRITE | GENERIC_READ;
+  if (HAS_FLAG (oflag, _O_WRONLY))
+    dwDesiredAccess |= GENERIC_WRITE;
+  if (HAS_FLAG (oflag, _O_APPEND))
+    dwDesiredAccess |= FILE_APPEND_DATA;
+
+  /* Construct shared mode.  */
+  /* https://docs.microsoft.com/en-us/windows/win32/fileio/file-attribute-constants */
+  DWORD dwShareMode = FILE_SHARE_READ | FILE_SHARE_WRITE;
+  if (HAS_FLAG (shflag, _SH_DENYRW))
+    dwShareMode &= ~(FILE_SHARE_READ | FILE_SHARE_WRITE);
+  if (HAS_FLAG (shflag, _SH_DENYWR))
+    dwShareMode &= ~FILE_SHARE_WRITE;
+  if (HAS_FLAG (shflag, _SH_DENYRD))
+    dwShareMode &= ~FILE_SHARE_READ;
+  if (HAS_FLAG (pmode, _S_IWRITE))
+    dwShareMode |= FILE_SHARE_READ | FILE_SHARE_WRITE;
+  if (HAS_FLAG (pmode, _S_IREAD))
+    dwShareMode |= FILE_SHARE_READ;
+
+  /* Override access mode with pmode if creating file.  */
+  if (HAS_FLAG (oflag, _O_CREAT))
+    {
+      if (HAS_FLAG (pmode, _S_IWRITE))
+        dwDesiredAccess |= FILE_GENERIC_WRITE;
+      if (HAS_FLAG (pmode, _S_IREAD))
+        dwDesiredAccess |= FILE_GENERIC_READ;
+    }
+
+  /* Create file disposition.  */
+  /* https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea */
+  DWORD dwCreationDisposition = 0;
+  if (HAS_FLAG (oflag, (_O_CREAT | _O_EXCL)))
+    dwCreationDisposition |= CREATE_NEW;
+  else if (HAS_FLAG (oflag, _O_TRUNC | _O_CREAT))
+    dwCreationDisposition |= CREATE_ALWAYS;
+  else if (HAS_FLAG (oflag, _O_TRUNC) && !HAS_FLAG (oflag, O_RDONLY))
+    dwCreationDisposition |= TRUNCATE_EXISTING;
+  else if (HAS_FLAG (oflag, _O_APPEND | _O_CREAT))
+    dwCreationDisposition |= OPEN_ALWAYS;
+  else if (HAS_FLAG (oflag, _O_APPEND))
+    dwCreationDisposition |= OPEN_EXISTING;
+  else if (HAS_FLAG (oflag, _O_CREAT))
+    dwCreationDisposition |= OPEN_ALWAYS;
+  else
+    dwCreationDisposition |= OPEN_EXISTING;
+
+  /* Set file access attributes.  */
+  DWORD dwFlagsAndAttributes = FILE_ATTRIBUTE_NORMAL;
+  if (HAS_FLAG (oflag, _O_RDONLY))
+    dwFlagsAndAttributes |= 0; /* No special attribute.  */
+  if (HAS_FLAG (oflag, _O_TEMPORARY))
+    {
+      dwFlagsAndAttributes |= FILE_FLAG_DELETE_ON_CLOSE;
+      dwShareMode |= FILE_SHARE_DELETE;
+    }
+  if (HAS_FLAG (oflag, _O_SHORT_LIVED))
+    dwFlagsAndAttributes |= FILE_ATTRIBUTE_TEMPORARY;
+  if (HAS_FLAG (oflag, _O_RANDOM))
+    dwFlagsAndAttributes |= FILE_FLAG_RANDOM_ACCESS;
+  if (HAS_FLAG (oflag, _O_SEQUENTIAL))
+    dwFlagsAndAttributes |= FILE_FLAG_SEQUENTIAL_SCAN;
+  /* Flag is only valid on it's own.  */
+  if (dwFlagsAndAttributes != FILE_ATTRIBUTE_NORMAL)
+    dwFlagsAndAttributes &= ~FILE_ATTRIBUTE_NORMAL;
+
+  /* Ensure we have shared read for files which are opened read-only. */
+  if (HAS_FLAG (dwCreationDisposition, OPEN_EXISTING)
+      && ((dwDesiredAccess & (GENERIC_WRITE|GENERIC_READ)) == GENERIC_READ))
+    dwShareMode |= FILE_SHARE_READ;
+
+  /* Set security attributes.  */
+  SECURITY_ATTRIBUTES securityAttributes;
+  ZeroMemory (&securityAttributes, sizeof(SECURITY_ATTRIBUTES));
+  securityAttributes.bInheritHandle       = !(oflag & _O_NOINHERIT);
+  securityAttributes.lpSecurityDescriptor = NULL;
+  securityAttributes.nLength              = sizeof(SECURITY_ATTRIBUTES);
+
+  wchar_t* _filename = FS(create_device_name) (filename);
+  if (!_filename)
+    return -1;
+
+  HANDLE hResult
+    = CreateFileW (_filename, dwDesiredAccess, dwShareMode, &securityAttributes,
+                   dwCreationDisposition, dwFlagsAndAttributes, NULL);
+
+  free (_filename);
+  if (INVALID_HANDLE_VALUE == hResult)
+    return setErrNoFromWin32Error ();
+
+  /* Now we have a Windows handle, we have to convert it to an FD and apply
+     the remaining flags.  */
+  const int flag_mask = _O_APPEND | _O_RDONLY | _O_TEXT | _O_WTEXT;
+  int fd = _open_osfhandle ((intptr_t)hResult, oflag & flag_mask);
+  if (-1 == fd)
+    return setErrNoFromWin32Error ();
+
+  /* Finally we can change the mode to the requested one.  */
+  const int mode_mask = _O_TEXT | _O_BINARY | _O_U16TEXT | _O_U8TEXT | _O_WTEXT;
+  if ((oflag & mode_mask) && (-1 == _setmode (fd, oflag & mode_mask)))
+    return setErrNoFromWin32Error ();
+
+  return fd;
+}
+
+int FS(translate_mode) (const wchar_t* mode)
+{
+  int oflag = 0;
+  int len = wcslen (mode);
+  int i;
+  #define IS_EXT(X) ((i < (len - 1)) && mode[i+1] == X)
+
+  for (i = 0; i < len; i++)
+    {
+      switch (mode[i])
+        {
+          case L'a':
+            if (IS_EXT (L'+'))
+              oflag |= _O_RDWR | _O_CREAT | _O_APPEND;
+            else
+              oflag |= _O_WRONLY | _O_CREAT | _O_APPEND;
+            break;
+          case L'r':
+            if (IS_EXT (L'+'))
+              oflag |= _O_RDWR;
+            else
+              oflag |= _O_RDONLY;
+            break;
+          case L'w':
+            if (IS_EXT (L'+'))
+              oflag |= _O_RDWR | _O_CREAT | _O_TRUNC;
+            else
+              oflag |= _O_WRONLY | _O_CREAT | _O_TRUNC;
+            break;
+          case L'b':
+            oflag |= _O_BINARY;
+            break;
+          case L't':
+            oflag |= _O_TEXT;
+            break;
+          case L'c':
+          case L'n':
+            oflag |= 0;
+            break;
+          case L'S':
+            oflag |= _O_SEQUENTIAL;
+            break;
+          case L'R':
+            oflag |= _O_RANDOM;
+            break;
+          case L'T':
+            oflag |= _O_SHORT_LIVED;
+            break;
+          case L'D':
+            oflag |= _O_TEMPORARY;
+            break;
+          default:
+            if (wcsncmp (mode, L"ccs=UNICODE", 11) == 0)
+              oflag |= _O_WTEXT;
+            else if (wcsncmp (mode, L"ccs=UTF-8", 9) == 0)
+              oflag |= _O_U8TEXT;
+            else if (wcsncmp (mode, L"ccs=UTF-16LE", 12) == 0)
+              oflag |= _O_U16TEXT;
+            else continue;
+        }
+    }
+  #undef IS_EXT
+
+  return oflag;
+}
+
+FILE *FS(fwopen) (const wchar_t* filename, const wchar_t* mode)
+{
+  int shflag = 0;
+  int pmode  = 0;
+  int oflag  = FS(translate_mode) (mode);
+
+  int fd = FS(swopen) (filename, oflag, shflag, pmode);
+  if (fd < 0)
+    return NULL;
+
+  FILE* file = _wfdopen (fd, mode);
+  return file;
+}
+
+FILE *FS(fopen) (const char* filename, const char* mode)
+{
+  wchar_t * const w_filename = FS(to_wide) (filename);
+  wchar_t * const w_mode = FS(to_wide) (mode);
+
+  FILE *result = FS(fwopen) (w_filename, w_mode);
+  free (w_filename);
+  free (w_mode);
+
+  return result;
+}
+
+int FS(sopen) (const char* filename, int oflag, int shflag, int pmode)
+{
+  wchar_t * const w_filename = FS(to_wide) (filename);
+  int result = FS(swopen) (w_filename, oflag, shflag, pmode);
+  free (w_filename);
+
+  return result;
+}
+
+int FS(_stat) (const char *path, struct _stat *buffer)
+{
+  wchar_t * const w_path = FS(to_wide) (path);
+  int result = FS(_wstat) (w_path, buffer);
+  free (w_path);
+
+  return result;
+}
+
+int FS(_stat64) (const char *path, struct __stat64 *buffer)
+{
+  wchar_t * const w_path = FS(to_wide) (path);
+  int result = FS(_wstat64) (w_path, buffer);
+  free (w_path);
+
+  return result;
+}
+
+static __time64_t ftToPosix(FILETIME ft)
+{
+  /* takes the last modified date.  */
+  LARGE_INTEGER date, adjust;
+  date.HighPart = ft.dwHighDateTime;
+  date.LowPart = ft.dwLowDateTime;
+
+  /* 100-nanoseconds = milliseconds * 10000.  */
+  /* A UNIX timestamp contains the number of seconds from Jan 1, 1970, while the
+     FILETIME documentation says: Contains a 64-bit value representing the
+     number of 100-nanosecond intervals since January 1, 1601 (UTC).
+
+     Between Jan 1, 1601 and Jan 1, 1970 there are 11644473600 seconds */
+  adjust.QuadPart = 11644473600000 * 10000;
+
+  /* removes the diff between 1970 and 1601.  */
+  date.QuadPart -= adjust.QuadPart;
+
+  /* converts back from 100-nanoseconds to seconds.  */
+  return (__time64_t)date.QuadPart / 10000000;
+}
+
+int FS(_wstat) (const wchar_t *path, struct _stat *buffer)
+{
+  ZeroMemory (buffer, sizeof (struct _stat));
+  wchar_t* _path = FS(create_device_name) (path);
+  if (!_path)
+    return -1;
+
+    /* Construct shared mode.  */
+  DWORD dwShareMode = FILE_SHARE_DELETE | FILE_SHARE_READ | FILE_SHARE_WRITE;
+  DWORD dwDesiredAccess = FILE_READ_ATTRIBUTES;
+  DWORD dwFlagsAndAttributes = FILE_FLAG_BACKUP_SEMANTICS;
+  DWORD dwCreationDisposition = OPEN_EXISTING;
+
+  SECURITY_ATTRIBUTES securityAttributes;
+  ZeroMemory (&securityAttributes, sizeof(SECURITY_ATTRIBUTES));
+  securityAttributes.bInheritHandle       = false;
+  securityAttributes.lpSecurityDescriptor = NULL;
+  securityAttributes.nLength              = sizeof(SECURITY_ATTRIBUTES);
+
+  HANDLE hResult
+    = CreateFileW (_path, dwDesiredAccess, dwShareMode, &securityAttributes,
+                   dwCreationDisposition, dwFlagsAndAttributes, NULL);
+
+  if (INVALID_HANDLE_VALUE == hResult)
+    {
+      free (_path);
+      return setErrNoFromWin32Error ();
+    }
+
+  WIN32_FILE_ATTRIBUTE_DATA finfo;
+  ZeroMemory (&finfo, sizeof (WIN32_FILE_ATTRIBUTE_DATA));
+  if(!GetFileAttributesExW (_path, GetFileExInfoStandard, &finfo))
+    {
+      free (_path);
+      CloseHandle (hResult);
+      return setErrNoFromWin32Error ();
+    }
+
+  unsigned short mode = _S_IREAD;
+
+  if (finfo.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
+    mode |= (_S_IFDIR | _S_IEXEC);
+  else
+  {
+    mode |= _S_IFREG;
+    DWORD type;
+    if (GetBinaryTypeW (_path, &type))
+      mode |= _S_IEXEC;
+  }
+
+  if (!(finfo.dwFileAttributes & FILE_ATTRIBUTE_READONLY))
+    mode |= _S_IWRITE;
+
+  buffer->st_mode  = mode;
+  buffer->st_nlink = 1;
+  buffer->st_size  = ((uint64_t)finfo.nFileSizeHigh << 32) + finfo.nFileSizeLow;
+  buffer->st_atime = ftToPosix (finfo.ftLastAccessTime);
+  buffer->st_mtime = buffer->st_ctime = ftToPosix (finfo.ftLastWriteTime);
+  free (_path);
+  CloseHandle (hResult);
+  return 0;
+}
+
+int FS(_wstat64) (const wchar_t *path, struct __stat64 *buffer)
+{
+  struct _stat buf;
+  ZeroMemory (buffer, sizeof (struct __stat64));
+
+  int result = FS(_wstat) (path, &buf);
+
+  buffer->st_mode = buf.st_mode;
+  buffer->st_nlink = 1;
+  buffer->st_size = buf.st_size;
+  buffer->st_atime = buf.st_atime;
+  buffer->st_mtime = buf.st_mtime;
+
+  return result;
+}
+
+int FS(_wrename) (const wchar_t *from, const wchar_t *to)
+{
+  wchar_t* const _from = FS(create_device_name) (from);
+  if (!_from)
+    return -1;
+
+  wchar_t* const _to = FS(create_device_name) (to);
+  if (!_to)
+    {
+      free (_from);
+      return -1;
+    }
+
+  if (MoveFileW(_from, _to) == 0) {
+    free (_from);
+    free (_to);
+    return setErrNoFromWin32Error ();
+  }
+
+
+  free (_from);
+  free (_to);
+  return 0;
+}
+
+int FS(rename) (const char *from, const char *to)
+{
+  wchar_t * const w_from = FS(to_wide) (from);
+  wchar_t * const w_to = FS(to_wide) (to);
+  int result = FS(_wrename) (w_from, w_to);
+  free(w_from);
+  free(w_to);
+
+  return result;
+}
+
+int FS(unlink) (const char *filename)
+{
+  return FS(_unlink) (filename);
+}
+
+int FS(_unlink) (const char *filename)
+{
+  wchar_t * const w_filename = FS(to_wide) (filename);
+  int result = FS(_wunlink) (w_filename);
+  free(w_filename);
+
+  return result;
+}
+
+int FS(_wunlink) (const wchar_t *filename)
+{
+  wchar_t* const _filename = FS(create_device_name) (filename);
+  if (!_filename)
+    return -1;
+
+  if (DeleteFileW(_filename) == 0) {
+    free (_filename);
+    return setErrNoFromWin32Error ();
+  }
+
+
+  free (_filename);
+  return 0;
+}
+int FS(remove) (const char *path)
+{
+  return FS(_unlink) (path);
+}
+int FS(_wremove) (const wchar_t *path)
+{
+  return FS(_wunlink) (path);
+}
+#else
+FILE *FS(fopen) (const char* filename, const char* mode)
+{
+  return fopen (filename, mode);
+}
+#endif
diff --git a/rts-fs/fs.h b/rts-fs/fs.h
new file mode 100644
index 000000000000..6c5f56ccdd7a
--- /dev/null
+++ b/rts-fs/fs.h
@@ -0,0 +1,55 @@
+/* -----------------------------------------------------------------------------
+ *
+ * (c) Tamar Christina 2018-2019
+ *
+ * Windows I/O routines for file opening.
+ *
+ * NOTE: Only modify this file in utils/fs/ and rerun configure. Do not edit
+ *       this file in any other directory as it will be overwritten.
+ *
+ * ---------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <stdio.h>
+
+#if !defined(FS_NAMESPACE)
+#define FS_NAMESPACE hs
+#endif
+
+/* Play some dirty tricks to get CPP to expand correctly.  */
+#define FS_FULL(ns, name) __##ns##_##name
+#define prefix FS_NAMESPACE
+#define FS_L(p, n) FS_FULL(p, n)
+#define FS(name) FS_L(prefix, name)
+
+#if defined(_WIN32)
+#include <wchar.h>
+// N.B. <sys/stat.h> defines some macro rewrites to, e.g., turn _wstat into
+// _wstat64i32. We must include it here to ensure tat this rewrite applies to
+// both the definition and use sites.
+#include <sys/types.h>
+#include <sys/stat.h>
+
+wchar_t* FS(create_device_name) (const wchar_t*);
+int FS(translate_mode) (const wchar_t*);
+int FS(swopen) (const wchar_t* filename, int oflag,
+                int shflag, int pmode);
+int FS(sopen) (const char* filename, int oflag,
+               int shflag, int pmode);
+FILE *FS(fwopen) (const wchar_t* filename, const wchar_t* mode);
+FILE *FS(fopen) (const char* filename, const char* mode);
+int FS(_stat) (const char *path, struct _stat *buffer);
+int FS(_stat64) (const char *path, struct __stat64 *buffer);
+int FS(_wstat) (const wchar_t *path, struct _stat *buffer);
+int FS(_wstat64) (const wchar_t *path, struct __stat64 *buffer);
+int FS(_wrename) (const wchar_t *from, const wchar_t *to);
+int FS(rename) (const char *from, const char *to);
+int FS(unlink) (const char *filename);
+int FS(_unlink) (const char *filename);
+int FS(_wunlink) (const wchar_t *filename);
+int FS(remove) (const char *path);
+int FS(_wremove) (const wchar_t *path);
+#else
+FILE *FS(fopen) (const char* filename, const char* mode);
+#endif
diff --git a/rts-fs/rts-fs.cabal b/rts-fs/rts-fs.cabal
new file mode 100644
index 000000000000..f013754d3f40
--- /dev/null
+++ b/rts-fs/rts-fs.cabal
@@ -0,0 +1,17 @@
+cabal-version:      3.0
+name:               rts-fs
+version:            1.0.0.0
+license:            NONE
+author:             Andrea Bedini
+maintainer:         andrea@andreabedini.com
+build-type:         Simple
+extra-doc-files:    README
+extra-source-files: fs.h
+
+library
+    cc-options:       -DFS_NAMESPACE=rts -DCOMPILING_RTS
+    cpp-options:      -DFS_NAMESPACE=rts -DCOMPILING_RTS
+    c-sources:        fs.c
+    include-dirs:     .
+    install-includes: fs.h
+    default-language: Haskell2010
diff --git a/rts/include/rts/Bytecodes.h b/rts-headers/include/rts/Bytecodes.h
similarity index 100%
rename from rts/include/rts/Bytecodes.h
rename to rts-headers/include/rts/Bytecodes.h
diff --git a/rts/include/rts/storage/ClosureTypes.h b/rts-headers/include/rts/storage/ClosureTypes.h
similarity index 100%
rename from rts/include/rts/storage/ClosureTypes.h
rename to rts-headers/include/rts/storage/ClosureTypes.h
diff --git a/rts/include/rts/storage/FunTypes.h b/rts-headers/include/rts/storage/FunTypes.h
similarity index 100%
rename from rts/include/rts/storage/FunTypes.h
rename to rts-headers/include/rts/storage/FunTypes.h
diff --git a/rts/include/stg/MachRegs.h b/rts-headers/include/stg/MachRegs.h
similarity index 100%
rename from rts/include/stg/MachRegs.h
rename to rts-headers/include/stg/MachRegs.h
diff --git a/rts/include/stg/MachRegs/arm32.h b/rts-headers/include/stg/MachRegs/arm32.h
similarity index 100%
rename from rts/include/stg/MachRegs/arm32.h
rename to rts-headers/include/stg/MachRegs/arm32.h
diff --git a/rts/include/stg/MachRegs/arm64.h b/rts-headers/include/stg/MachRegs/arm64.h
similarity index 100%
rename from rts/include/stg/MachRegs/arm64.h
rename to rts-headers/include/stg/MachRegs/arm64.h
diff --git a/rts/include/stg/MachRegs/loongarch64.h b/rts-headers/include/stg/MachRegs/loongarch64.h
similarity index 100%
rename from rts/include/stg/MachRegs/loongarch64.h
rename to rts-headers/include/stg/MachRegs/loongarch64.h
diff --git a/rts/include/stg/MachRegs/ppc.h b/rts-headers/include/stg/MachRegs/ppc.h
similarity index 100%
rename from rts/include/stg/MachRegs/ppc.h
rename to rts-headers/include/stg/MachRegs/ppc.h
diff --git a/rts/include/stg/MachRegs/riscv64.h b/rts-headers/include/stg/MachRegs/riscv64.h
similarity index 100%
rename from rts/include/stg/MachRegs/riscv64.h
rename to rts-headers/include/stg/MachRegs/riscv64.h
diff --git a/rts/include/stg/MachRegs/s390x.h b/rts-headers/include/stg/MachRegs/s390x.h
similarity index 100%
rename from rts/include/stg/MachRegs/s390x.h
rename to rts-headers/include/stg/MachRegs/s390x.h
diff --git a/rts/include/stg/MachRegs/wasm32.h b/rts-headers/include/stg/MachRegs/wasm32.h
similarity index 100%
rename from rts/include/stg/MachRegs/wasm32.h
rename to rts-headers/include/stg/MachRegs/wasm32.h
diff --git a/rts/include/stg/MachRegs/x86.h b/rts-headers/include/stg/MachRegs/x86.h
similarity index 100%
rename from rts/include/stg/MachRegs/x86.h
rename to rts-headers/include/stg/MachRegs/x86.h
diff --git a/rts-headers/rts-headers.cabal b/rts-headers/rts-headers.cabal
new file mode 100644
index 000000000000..6d1b89a7ca33
--- /dev/null
+++ b/rts-headers/rts-headers.cabal
@@ -0,0 +1,31 @@
+cabal-version: 3.4
+name: rts-headers
+version: 1.0.3
+synopsis: The GHC runtime system
+description:
+    The GHC runtime system.
+
+    Code produced by GHC links this library to provide missing functionality
+    that cannot be written in Haskell itself.
+license: BSD-3-Clause
+maintainer: glasgow-haskell-users@haskell.org
+build-type: Simple
+
+
+library
+  include-dirs:
+    include
+  
+  install-includes:
+    rts/Bytecodes.h
+    rts/storage/ClosureTypes.h
+    rts/storage/FunTypes.h
+    stg/MachRegs.h
+    stg/MachRegs/arm32.h
+    stg/MachRegs/arm64.h
+    stg/MachRegs/loongarch64.h
+    stg/MachRegs/ppc.h
+    stg/MachRegs/riscv64.h
+    stg/MachRegs/s390x.h
+    stg/MachRegs/wasm32.h
+    stg/MachRegs/x86.h
diff --git a/rts/.gitignore b/rts/.gitignore
index 179d62d55cf7..f1a295e18db0 100644
--- a/rts/.gitignore
+++ b/rts/.gitignore
@@ -8,7 +8,6 @@
 /package.conf.inplace.raw
 /package.conf.install
 /package.conf.install.raw
-/fs.*
 
 /aclocal.m4
 /autom4te.cache/
diff --git a/rts/configure.ac b/rts/configure.ac
index e9181aaf552a..ae110d76dce7 100644
--- a/rts/configure.ac
+++ b/rts/configure.ac
@@ -178,10 +178,12 @@ dnl Check for libraries
 dnl ################################################################
 
 dnl ** check whether we need -ldl to get dlopen()
-AC_CHECK_LIB([dl], [dlopen])
+AC_SEARCH_LIBS([dlopen], [dl])
 dnl ** check whether we have dlinfo
 AC_CHECK_FUNCS([dlinfo])
 
+FP_CHECK_PTHREAD_LIB
+
 dnl --------------------------------------------------
 dnl * Miscellaneous feature tests
 dnl --------------------------------------------------
@@ -520,3 +522,118 @@ cat $srcdir/rts.buildinfo.in \
     || exit 1
 rm -f external-symbols.flags
 ]
+
+AC_SUBST([EXTRA_LIBS],[` printf " %s " "$LIBS" | sed -E 's/ -l([[^ ]]*)/\1 /g' `])
+AS_IF(
+  [test "`echo $EXTRA_LIBS | sed 's/ //'`" != ""],
+  [echo "extra-libraries: $EXTRA_LIBS" >> rts.buildinfo])
+
+dnl --------------------------------------------------------------
+dnl Generate derived constants
+dnl --------------------------------------------------------------
+
+AC_ARG_VAR([NM], [Path to the nm program])
+AC_PATH_PROG([NM], nm)
+if test -z "$NM"; then
+	AC_MSG_ERROR([Cannot find nm])
+fi
+
+AC_ARG_VAR([OBJDUMP], [Path to the objdump program])
+AC_PATH_PROG([OBJDUMP], objdump)
+if test -z "$OBJDUMP"; then
+	AC_MSG_ERROR([Cannot find objdump])
+fi
+
+AC_ARG_VAR([DERIVE_CONSTANTS], [Path to the deriveConstants program])
+AC_PATH_PROG([DERIVE_CONSTANTS], deriveConstants)
+AS_IF([test "x$DERIVE_CONSTANTS" = x], [AC_MSG_ERROR([deriveConstants executable not found. Please install deriveConstants or set DERIVE_CONSTANTS environment variable.])])
+
+AC_ARG_VAR([GENAPPLY], [Path to the genapply program])
+AC_PATH_PROG([GENAPPLY], genapply)
+AS_IF([test "x$GENAPPLY" = x], [AC_MSG_ERROR([genapply executable not found. Please install genapply or set GENAPPLY environment variable.])])
+
+AC_CHECK_PROGS([PYTHON], [python3 python python2])
+AS_IF([test "x$PYTHON" = x], [AC_MSG_ERROR([Python interpreter not found. Please install Python or set PYTHON environment variable.])])
+
+AC_MSG_CHECKING([for DerivedConstants.h])
+dnl NOTE:  dnl pass `-fcommon` to force symbols into the common section. If they end
+dnl up in the ro data section `nm` won't list their size, and thus derivedConstants
+dnl will fail. Recent clang (e.g. 16) will by default use `-fno-common`.
+dnl
+dnl FIXME: using a relative path here is TERRIBLE; Cabal should provide some
+dnl        env var for _build-dependencies_ headers!
+dnl
+
+if $DERIVE_CONSTANTS \
+  --gen-header \
+  -o include/DerivedConstants.h \
+  --target-os "$HostOS_CPP" \
+  --gcc-program "$CC" \
+  --nm-program "$NM" \
+  --objdump-program "$OBJDUMP" \
+  --tmpdir "$(mktemp -d)" \
+  --gcc-flag "-fcommon" \
+  --gcc-flag "-I$srcdir" \
+  --gcc-flag "-I$srcdir/include" \
+  --gcc-flag "-Iinclude" \
+  --gcc-flag "-I$srcdir/../rts-headers/include" ; then
+  AC_MSG_RESULT([created])
+else
+  AC_MSG_RESULT([failed to create])
+  AC_MSG_ERROR([Failed to run $DERIVE_CONSTANTS --gen-header ...])
+fi
+
+AC_MSG_CHECKING([for AutoApply.cmm])
+if $GENAPPLY include/DerivedConstants.h > AutoApply.cmm; then
+  AC_MSG_RESULT([created])
+else
+  AC_MSG_RESULT([failed to create])
+  AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h > AutoApply.cmm])
+fi
+
+AC_MSG_CHECKING([for AutoApply_V16.cmm])
+if $GENAPPLY include/DerivedConstants.h -V16 > AutoApply_V16.cmm; then
+  AC_MSG_RESULT([created])
+else
+  AC_MSG_RESULT([failed to create])
+  AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h -V16 > AutoApply_V16.cmm])
+fi
+
+AC_MSG_CHECKING([for AutoApply_V32.cmm])
+if $GENAPPLY include/DerivedConstants.h -V32 > AutoApply_V32.cmm; then
+  AC_MSG_RESULT([created])
+else
+  AC_MSG_RESULT([failed to create])
+  AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h -V32 > AutoApply_V32.cmm])
+fi
+
+AC_MSG_CHECKING([for AutoApply_V64.cmm])
+if $GENAPPLY include/DerivedConstants.h -V64 > AutoApply_V64.cmm; then
+  AC_MSG_RESULT([created])
+else
+  AC_MSG_RESULT([failed to create])
+  AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h -V64 > AutoApply_V64.cmm])
+fi
+
+AC_MSG_CHECKING([for include/rts/EventLogConstants.h])
+if mkdir -p include/rts && $PYTHON $srcdir/gen_event_types.py --event-types-defines include/rts/EventLogConstants.h; then
+  AC_MSG_RESULT([created])
+else
+  AC_MSG_RESULT([failed to create])
+  AC_MSG_ERROR([Failed to run $PYTHON gen_event_types.py])
+fi
+
+AC_MSG_CHECKING([for include/rts/EventTypes.h])
+if mkdir -p include/rts && $PYTHON $srcdir/gen_event_types.py --event-types-array include/rts/EventTypes.h; then
+  AC_MSG_RESULT([created])
+else
+  AC_MSG_RESULT([failed to create])
+  AC_MSG_ERROR([Failed to run $PYTHON gen_event_types.py])
+fi
+
+
+dnl --------------------------------------------------------------
+dnl ** Write config files
+dnl --------------------------------------------------------------
+
+AC_OUTPUT
diff --git a/rts/include/stg/MachRegsForHost.h b/rts/include/stg/MachRegsForHost.h
index 7c045c0214bf..cd28215ea0f1 100644
--- a/rts/include/stg/MachRegsForHost.h
+++ b/rts/include/stg/MachRegsForHost.h
@@ -84,4 +84,4 @@
 
 #endif
 
-#include "MachRegs.h"
+#include "stg/MachRegs.h"
diff --git a/rts/rts.cabal b/rts/rts.cabal
index 20817ef0d63a..5baef6e02a20 100644
--- a/rts/rts.cabal
+++ b/rts/rts.cabal
@@ -1,4 +1,4 @@
-cabal-version: 3.0
+cabal-version: 3.8
 name: rts
 version: 1.0.3
 synopsis: The GHC runtime system
@@ -13,9 +13,234 @@ build-type: Configure
 
 extra-source-files:
     configure
+    config.guess
+    config.sub
+    ghcplatform.h.top.in
+    ghcplatform.h.bottom
+    ghcautoconf.h.autoconf.in
     configure.ac
     external-symbols.list.in
     rts.buildinfo.in
+    linker/ELFRelocs/AArch64.def
+    linker/ELFRelocs/ARM.def
+    linker/ELFRelocs/i386.def
+    linker/ELFRelocs/x86_64.def
+    win32/libHSffi.def
+    win32/libHSghc-internal.def
+    win32/libHSghc-prim.def
+    posix/ticker/Pthread.c
+    posix/ticker/Setitimer.c
+    posix/ticker/TimerCreate.c
+    posix/ticker/TimerFd.c
+    -- headers files that are not installed by the rts package but only used to
+    -- build the rts C code
+    xxhash.h
+    adjustor/AdjustorPool.h
+    Adjustor.h
+    Apply.h
+    Arena.h
+    ARMOutlineAtomicsSymbols.h
+    AutoApply.h
+    AutoApplyVecs.h
+    BeginPrivate.h
+    Capability.h
+    CheckUnload.h
+    CheckVectorSupport.h
+    CloneStack.h
+    Continuation.h
+    Disassembler.h
+    EndPrivate.h
+    eventlog/EventLog.h
+    Excn.h
+    FileLock.h
+    ForeignExports.h
+    fs_rts.h
+    GetEnv.h
+    GetTime.h
+    Globals.h
+    Hash.h
+    hooks/Hooks.h
+    include/Cmm.h
+    include/ghcconfig.h
+    include/HsFFI.h
+    include/MachDeps.h
+    include/rts/Adjustor.h
+    include/RtsAPI.h
+    include/rts/BlockSignals.h
+    include/rts/Config.h
+    include/rts/Constants.h
+    include/rts/EventLogFormat.h
+    include/rts/EventLogWriter.h
+    include/rts/ExecPage.h
+    include/rts/FileLock.h
+    include/rts/Flags.h
+    include/rts/ForeignExports.h
+    include/rts/GetTime.h
+    include/rts/ghc_ffi.h
+    include/rts/Globals.h
+    include/Rts.h
+    include/rts/Hpc.h
+    include/rts/IOInterface.h
+    include/rts/IPE.h
+    include/rts/Libdw.h
+    include/rts/LibdwPool.h
+    include/rts/Linker.h
+    include/rts/Main.h
+    include/rts/Messages.h
+    include/rts/NonMoving.h
+    include/rts/OSThreads.h
+    include/rts/Parallel.h
+    include/rts/PosixSource.h
+    include/rts/PrimFloat.h
+    include/rts/prof/CCS.h
+    include/rts/prof/Heap.h
+    include/rts/Profiling.h
+    include/rts/prof/LDV.h
+    include/rts/Signals.h
+    include/rts/SpinLock.h
+    include/rts/StableName.h
+    include/rts/StablePtr.h
+    include/rts/StaticPtrTable.h
+    include/rts/storage/Block.h
+    include/rts/storage/ClosureMacros.h
+    include/rts/storage/GC.h
+    include/rts/storage/HeapAlloc.h
+    include/rts/storage/Heap.h
+    include/rts/storage/InfoTables.h
+    include/rts/storage/MBlock.h
+    include/rts/storage/TSO.h
+    include/rts/Threads.h
+    include/rts/Ticky.h
+    include/rts/Time.h
+    include/rts/Timer.h
+    include/rts/TSANUtils.h
+    include/rts/TTY.h
+    include/rts/Types.h
+    include/rts/Utils.h
+    include/stg/DLL.h
+    include/Stg.h
+    include/stg/MachRegsForHost.h
+    include/stg/MiscClosures.h
+    include/stg/Prim.h
+    include/stg/Regs.h
+    include/stg/SMP.h
+    include/stg/Ticky.h
+    include/stg/Types.h
+    Interpreter.h
+    IOManager.h
+    IOManagerInternals.h
+    IPE.h
+    Jumps.h
+    LdvProfile.h
+    Libdw.h
+    LibdwPool.h
+    linker/CacheFlush.h
+    linker/elf_compat.h
+    linker/elf_got.h
+    linker/Elf.h
+    linker/elf_plt_aarch64.h
+    linker/elf_plt_arm.h
+    linker/elf_plt.h
+    linker/elf_plt_riscv64.h
+    linker/elf_reloc_aarch64.h
+    linker/elf_reloc.h
+    linker/elf_reloc_riscv64.h
+    linker/ElfTypes.h
+    linker/elf_util.h
+    linker/InitFini.h
+    LinkerInternals.h
+    linker/LoadNativeObjPosix.h
+    linker/M32Alloc.h
+    linker/MachO.h
+    linker/macho/plt_aarch64.h
+    linker/macho/plt.h
+    linker/MachOTypes.h
+    linker/MMap.h
+    linker/PEi386.h
+    linker/PEi386Types.h
+    linker/SymbolExtras.h
+    linker/util.h
+    linker/Wasm32Types.h
+    Messages.h
+    PathUtils.h
+    Pool.h
+    posix/Clock.h
+    posix/Select.h
+    posix/Signals.h
+    posix/TTY.h
+    Prelude.h
+    Printer.h
+    ProfHeap.h
+    ProfHeapInternal.h
+    ProfilerReport.h
+    ProfilerReportJson.h
+    Profiling.h
+    Proftimer.h
+    RaiseAsync.h
+    ReportMemoryMap.h
+    RetainerProfile.h
+    RetainerSet.h
+    RtsDllMain.h
+    RtsFlags.h
+    RtsSignals.h
+    RtsSymbolInfo.h
+    RtsSymbols.h
+    RtsUtils.h
+    Schedule.h
+    sm/BlockAlloc.h
+    sm/CNF.h
+    sm/Compact.h
+    sm/Evac.h
+    sm/GC.h
+    sm/GCTDecl.h
+    sm/GCThread.h
+    sm/GCUtils.h
+    sm/HeapUtils.h
+    sm/MarkStack.h
+    sm/MarkWeak.h
+    sm/NonMovingAllocate.h
+    sm/NonMovingCensus.h
+    sm/NonMoving.h
+    sm/NonMovingMark.h
+    sm/NonMovingScav.h
+    sm/NonMovingShortcut.h
+    sm/NonMovingSweep.h
+    sm/OSMem.h
+    SMPClosureOps.h
+    sm/Sanity.h
+    sm/Scav.h
+    sm/ShouldCompact.h
+    sm/Storage.h
+    sm/Sweep.h
+    Sparks.h
+    StableName.h
+    StablePtr.h
+    StaticPtrTable.h
+    Stats.h
+    StgPrimFloat.h
+    StgRun.h
+    STM.h
+    Task.h
+    ThreadLabels.h
+    ThreadPaused.h
+    Threads.h
+    Ticker.h
+    Ticky.h
+    Timer.h
+    TopHandler.h
+    Trace.h
+    TraverseHeap.h
+    Updates.h
+    Weak.h
+    win32/AsyncMIO.h
+    win32/AsyncWinIO.h
+    win32/AwaitEvent.h
+    win32/ConsoleHandler.h
+    win32/MIOManager.h
+    win32/ThrIOManager.h
+    win32/veh_excn.h
+    win32/WorkQueue.h
+    WSDeque.h
 
 extra-tmp-files:
     autom4te.cache
@@ -34,18 +259,9 @@ flag libm
 flag librt
   default: False
   manual: True
-flag libdl
-  default: False
-  manual: True
-flag use-system-libffi
-  default: False
-  manual: True
 flag libffi-adjustors
   default: False
   manual: True
-flag need-pthread
-  default: False
-  manual: True
 flag libbfd
   default: False
   manual: True
@@ -79,11 +295,11 @@ flag smp
 flag find-ptr
   default: False
   manual: True
--- Some cabal flags used to control the flavours we want to produce
--- for libHSrts in hadrian. By default, we just produce vanilla and
--- threaded. The flags "compose": if you enable debug and profiling,
--- you will produce vanilla, _thr, _debug, _p but also _thr_p,
--- _thr_debug_p and so on.
+-- -- Some cabal flags used to control the flavours we want to produce
+-- -- for libHSrts in hadrian. By default, we just produce vanilla and
+-- -- threaded. The flags "compose": if you enable debug and profiling,
+-- -- you will produce vanilla, _thr, _debug, _p but also _thr_p,
+-- -- _thr_debug_p and so on.
 flag profiling
   default: False
   manual: True
@@ -104,472 +320,480 @@ flag thread-sanitizer
   default: False
   manual: True
 
-library
-    -- rts is a wired in package and
-    -- expects the unit-id to be
-    -- set without version
-    ghc-options: -this-unit-id rts
-
-    exposed: True
-    exposed-modules:
+common rts-base-config
+    ghc-options: -ghcversion-file=include/ghcversion.h -optc-DFS_NAMESPACE=rts
+    cmm-options:
 
-    if arch(javascript)
+    include-dirs: include .
+    includes: Rts.h
+    build-depends:
+      rts-headers,
+      rts-fs,
+      rts
 
-      include-dirs: include
-
-      js-sources:
-        js/config.js
-        js/structs.js
-        js/arith.js
-        js/compact.js
-        js/debug.js
-        js/enum.js
-        js/environment.js
-        js/eventlog.js
-        js/gc.js
-        js/goog.js
-        js/hscore.js
-        js/md5.js
-        js/mem.js
-        js/node-exports.js
-        js/object.js
-        js/profiling.js
-        js/rts.js
-        js/stableptr.js
-        js/staticpointer.js
-        js/stm.js
-        js/string.js
-        js/thread.js
-        js/unicode.js
-        js/verify.js
-        js/weak.js
-        js/globals.js
-        js/time.js
-
-      install-includes: HsFFI.h MachDeps.h Rts.h RtsAPI.h Stg.h
-                        ghcautoconf.h ghcconfig.h ghcplatform.h ghcversion.h
-                        DerivedConstants.h
-                        stg/MachRegs.h
-                        stg/MachRegs/arm32.h
-                        stg/MachRegs/arm64.h
-                        stg/MachRegs/loongarch64.h
-                        stg/MachRegs/ppc.h
-                        stg/MachRegs/riscv64.h
-                        stg/MachRegs/s390x.h
-                        stg/MachRegs/wasm32.h
-                        stg/MachRegs/x86.h
-                        stg/MachRegsForHost.h
-                        stg/Types.h
+common rts-c-sources-base
+    if !arch(javascript)
+      cmm-sources:
+        Apply.cmm
+        Compact.cmm
+        ContinuationOps.cmm
+        Exception.cmm
+        HeapStackCheck.cmm
+        Jumps_D.cmm
+        Jumps_V16.cmm
+        PrimOps.cmm
+        StgMiscClosures.cmm
+        StgStartup.cmm
+        StgStdThunks.cmm
+        Updates.cmm
 
+    -- Adjustor stuff
+    if flag(libffi-adjustors)
+      c-sources: adjustor/LibffiAdjustor.c
     else
-      -- If we are using an in-tree libffi then we must declare it as a bundled
-      -- library to ensure that Cabal installs it.
-      if !flag(use-system-libffi)
-        if os(windows)
-          extra-bundled-libraries: Cffi-6
+      if arch(i386)
+        asm-sources: adjustor/Nativei386Asm.S
+        c-sources: adjustor/Nativei386.c
+      if arch(x86_64)
+        if os(mingw32)
+          asm-sources: adjustor/NativeAmd64MingwAsm.S
+          c-sources: adjustor/NativeAmd64Mingw.c
         else
-          extra-bundled-libraries: Cffi
-
-        install-includes: ffi.h ffitarget.h
-        -- ^ see Note [Packaging libffi headers] in
-        -- GHC.Driver.CodeOutput.
-
-      -- Here we declare several flavours to be available when passing the
-      -- suitable (combination of) flag(s) when configuring the RTS from hadrian,
-      -- using Cabal.
-      if flag(threaded)
-        extra-library-flavours: _thr
-        if flag(dynamic)
-          extra-dynamic-library-flavours: _thr
-
-      if flag(profiling)
-        extra-library-flavours: _p
-        if flag(threaded)
-          extra-library-flavours: _thr_p
-        if flag(debug)
-          extra-library-flavours: _debug_p
-          if flag(threaded)
-            extra-library-flavours: _thr_debug_p
-        if flag(dynamic)
-          extra-dynamic-library-flavours: _p
-          if flag(threaded)
-            extra-dynamic-library-flavours: _thr_p
-          if flag(debug)
-            extra-dynamic-library-flavours: _debug_p
-            if flag(threaded)
-              extra-dynamic-library-flavours: _thr_debug_p
-
-      if flag(debug)
-        extra-library-flavours: _debug
-        if flag(dynamic)
-          extra-dynamic-library-flavours: _debug
-        if flag(threaded)
-          extra-library-flavours: _thr_debug
-          if flag(dynamic)
-            extra-dynamic-library-flavours: _thr_debug
-
-      if flag(thread-sanitizer)
-        cc-options: -fsanitize=thread
-        ld-options: -fsanitize=thread
-
-      if os(linux)
-         -- the RTS depends upon libc. while this dependency is generally
-         -- implicitly added by `cc`, we must explicitly add it here to ensure
-         -- that it is ordered correctly with libpthread, since ghc-internal.cabal
-         -- also explicitly lists libc. See #19029.
-         extra-libraries: c
-      if flag(libm)
-         -- for ldexp()
-         extra-libraries: m
-      if flag(librt)
-         extra-libraries: rt
-      if flag(libdl)
-         extra-libraries: dl
-      if flag(use-system-libffi)
-         extra-libraries: ffi
-      if os(windows)
-         extra-libraries:
-            -- for the linker
-            wsock32 gdi32 winmm
-            -- for crash dump
-            dbghelp
-            -- for process information
-            psapi
-         -- TODO: Hadrian will use this cabal file, so drop WINVER from Hadrian's configs.
-         -- Minimum supported Windows version.
-         -- These numbers can be found at:
-         --  https://msdn.microsoft.com/en-us/library/windows/desktop/aa383745(v=vs.85).aspx
-         -- If we're compiling on windows, enforce that we only support Windows 7+
-         -- Adding this here means it doesn't have to be done in individual .c files
-         -- and also centralizes the versioning.
-         cpp-options: -D_WIN32_WINNT=0x06010000
-         cc-options: -D_WIN32_WINNT=0x06010000
-      if flag(need-pthread)
-         -- for pthread_getthreadid_np, pthread_create, ...
-         extra-libraries: pthread
-      if flag(need-atomic)
-         -- for sub-word-sized atomic operations (#19119)
-         extra-libraries: atomic
-      if flag(libbfd)
-         -- for debugging
-         extra-libraries: bfd iberty
-      if flag(libdw)
-         -- for backtraces
-         extra-libraries: elf dw
-      if flag(libnuma)
-         extra-libraries: numa
-      if flag(libzstd)
-         if flag(static-libzstd)
-            if os(darwin)
-               buildable: False
-            else
-               extra-libraries: :libzstd.a
-         else
-            extra-libraries: zstd
-      if !flag(smp)
-         cpp-options: -DNOSMP
-
-      include-dirs: include
-      includes: Rts.h
-      autogen-includes: ghcautoconf.h ghcplatform.h
-      install-includes: Cmm.h HsFFI.h MachDeps.h Jumps.h Rts.h RtsAPI.h RtsSymbols.h Stg.h
-                        ghcautoconf.h ghcconfig.h ghcplatform.h ghcversion.h
-                        -- ^ from include
-                        DerivedConstants.h
-                        rts/EventLogConstants.h
-                        rts/EventTypes.h
-                        -- ^ generated
-                        rts/ghc_ffi.h
-                        rts/Adjustor.h
-                        rts/ExecPage.h
-                        rts/BlockSignals.h
-                        rts/Bytecodes.h
-                        rts/Config.h
-                        rts/Constants.h
-                        rts/EventLogFormat.h
-                        rts/EventLogWriter.h
-                        rts/FileLock.h
-                        rts/Flags.h
-                        rts/ForeignExports.h
-                        rts/GetTime.h
-                        rts/Globals.h
-                        rts/Hpc.h
-                        rts/IOInterface.h
-                        rts/Libdw.h
-                        rts/LibdwPool.h
-                        rts/Linker.h
-                        rts/Main.h
-                        rts/Messages.h
-                        rts/NonMoving.h
-                        rts/OSThreads.h
-                        rts/Parallel.h
-                        rts/PrimFloat.h
-                        rts/Profiling.h
-                        rts/IPE.h
-                        rts/PosixSource.h
-                        rts/Signals.h
-                        rts/SpinLock.h
-                        rts/StableName.h
-                        rts/StablePtr.h
-                        rts/StaticPtrTable.h
-                        rts/TTY.h
-                        rts/Threads.h
-                        rts/Ticky.h
-                        rts/Time.h
-                        rts/Timer.h
-                        rts/TSANUtils.h
-                        rts/Types.h
-                        rts/Utils.h
-                        rts/prof/CCS.h
-                        rts/prof/Heap.h
-                        rts/prof/LDV.h
-                        rts/storage/Block.h
-                        rts/storage/ClosureMacros.h
-                        rts/storage/ClosureTypes.h
-                        rts/storage/Closures.h
-                        rts/storage/FunTypes.h
-                        rts/storage/Heap.h
-                        rts/storage/HeapAlloc.h
-                        rts/storage/GC.h
-                        rts/storage/InfoTables.h
-                        rts/storage/MBlock.h
-                        rts/storage/TSO.h
-                        stg/DLL.h
-                        stg/MachRegs.h
-                        stg/MachRegs/arm32.h
-                        stg/MachRegs/arm64.h
-                        stg/MachRegs/loongarch64.h
-                        stg/MachRegs/ppc.h
-                        stg/MachRegs/riscv64.h
-                        stg/MachRegs/s390x.h
-                        stg/MachRegs/wasm32.h
-                        stg/MachRegs/x86.h
-                        stg/MachRegsForHost.h
-                        stg/MiscClosures.h
-                        stg/Prim.h
-                        stg/Regs.h
-                        stg/SMP.h
-                        stg/Ticky.h
-                        stg/Types.h
-
-      if os(osx)
-        ld-options: "-Wl,-search_paths_first"
-                    -- See Note [Undefined symbols in the RTS]
-                    "-Wl,-undefined,dynamic_lookup"
-        if !arch(x86_64) && !arch(aarch64)
-           ld-options: -read_only_relocs warning
-
-      cmm-sources: Apply.cmm
-                   Compact.cmm
-                   ContinuationOps.cmm
-                   Exception.cmm
-                   HeapStackCheck.cmm
-                   Jumps_D.cmm
-                   Jumps_V16.cmm
-                   Jumps_V32.cmm
-                   Jumps_V64.cmm
-                   PrimOps.cmm
-                   StgMiscClosures.cmm
-                   StgStartup.cmm
-                   StgStdThunks.cmm
-                   Updates.cmm
-                   -- AutoApply is generated
-                   AutoApply.cmm
-                   AutoApply_V16.cmm
-                   AutoApply_V32.cmm
-                   AutoApply_V64.cmm
-
-      -- Adjustor stuff
-      if flag(libffi-adjustors)
+          asm-sources: adjustor/NativeAmd64Asm.S
+          c-sources: adjustor/NativeAmd64.c
+      if !arch(x86_64) && !arch(i386)
         c-sources: adjustor/LibffiAdjustor.c
-      else
-        -- Use GHC's native adjustors
-        if arch(i386)
-          asm-sources: adjustor/Nativei386Asm.S
-          c-sources: adjustor/Nativei386.c
-        if arch(x86_64)
-          if os(mingw32)
-            asm-sources: adjustor/NativeAmd64MingwAsm.S
-            c-sources: adjustor/NativeAmd64Mingw.c
-          else
-            asm-sources: adjustor/NativeAmd64Asm.S
-            c-sources: adjustor/NativeAmd64.c
-
-      -- Use assembler STG entrypoint on architectures where it is used
-      if arch(ppc) || arch(ppc64) || arch(s390x) || arch(riscv64) || arch(loongarch64)
-        asm-sources: StgCRunAsm.S
-
-      c-sources: Adjustor.c
-                 AllocArray.c
-                 adjustor/AdjustorPool.c
-                 ExecPage.c
-                 Arena.c
-                 Capability.c
-                 CheckUnload.c
-                 CheckVectorSupport.c
-                 CloneStack.c
-                 ClosureFlags.c
-                 ClosureSize.c
-                 Continuation.c
-                 Disassembler.c
-                 FileLock.c
-                 ForeignExports.c
-                 Globals.c
-                 Hash.c
-                 Heap.c
-                 Hpc.c
-                 HsFFI.c
-                 Inlines.c
-                 Interpreter.c
-                 IOManager.c
-                 LdvProfile.c
-                 Libdw.c
-                 LibdwPool.c
-                 Linker.c
-                 ReportMemoryMap.c
-                 Messages.c
-                 OldARMAtomic.c
-                 PathUtils.c
-                 Pool.c
-                 Printer.c
-                 ProfHeap.c
-                 ProfilerReport.c
-                 ProfilerReportJson.c
-                 Profiling.c
-                 IPE.c
-                 Proftimer.c
-                 RaiseAsync.c
-                 RetainerProfile.c
-                 RetainerSet.c
-                 RtsAPI.c
-                 RtsDllMain.c
-                 RtsFlags.c
-                 RtsMain.c
-                 RtsMessages.c
-                 RtsStartup.c
-                 RtsSymbolInfo.c
-                 RtsSymbols.c
-                 RtsUtils.c
-                 STM.c
-                 Schedule.c
-                 Sparks.c
-                 SpinLock.c
-                 StableName.c
-                 StablePtr.c
-                 StaticPtrTable.c
-                 Stats.c
-                 StgCRun.c
-                 StgPrimFloat.c
-                 Task.c
-                 ThreadLabels.c
-                 ThreadPaused.c
-                 Threads.c
-                 Ticky.c
-                 Timer.c
-                 TopHandler.c
-                 Trace.c
-                 TraverseHeap.c
-                 TraverseHeapTest.c
-                 TSANUtils.c
-                 WSDeque.c
-                 Weak.c
-                 ZeroSlop.c
-                 eventlog/EventLog.c
-                 eventlog/EventLogWriter.c
-                 hooks/FlagDefaults.c
-                 hooks/LongGCSync.c
-                 hooks/MallocFail.c
-                 hooks/OnExit.c
-                 hooks/OutOfHeap.c
-                 hooks/StackOverflow.c
-                 linker/CacheFlush.c
-                 linker/Elf.c
-                 linker/InitFini.c
-                 linker/LoadArchive.c
-                 linker/LoadNativeObjPosix.c
-                 linker/M32Alloc.c
-                 linker/MMap.c
-                 linker/MachO.c
-                 linker/macho/plt.c
-                 linker/macho/plt_aarch64.c
-                 linker/ProddableBlocks.c
-                 linker/PEi386.c
-                 linker/SymbolExtras.c
-                 linker/elf_got.c
-                 linker/elf_plt.c
-                 linker/elf_plt_aarch64.c
-                 linker/elf_plt_riscv64.c
-                 linker/elf_plt_arm.c
-                 linker/elf_reloc.c
-                 linker/elf_reloc_aarch64.c
-                 linker/elf_reloc_riscv64.c
-                 linker/elf_tlsgd.c
-                 linker/elf_util.c
-                 sm/BlockAlloc.c
-                 sm/CNF.c
-                 sm/Compact.c
-                 sm/Evac.c
-                 sm/Evac_thr.c
-                 sm/GC.c
-                 sm/GCAux.c
-                 sm/GCUtils.c
-                 sm/MBlock.c
-                 sm/MarkWeak.c
-                 sm/NonMoving.c
-                 sm/NonMovingAllocate.c
-                 sm/NonMovingCensus.c
-                 sm/NonMovingMark.c
-                 sm/NonMovingScav.c
-                 sm/NonMovingShortcut.c
-                 sm/NonMovingSweep.c
-                 sm/Sanity.c
-                 sm/Scav.c
-                 sm/Scav_thr.c
-                 sm/Storage.c
-                 sm/Sweep.c
-                 fs.c
+
+    if arch(ppc) || arch(ppc64) || arch(s390x) || arch(riscv64) || arch(loongarch64)
+      asm-sources: StgCRunAsm.S
+
+    if arch(wasm32)
+      cc-options: -fvisibility=default -fvisibility-inlines-hidden
+
+    c-sources: Adjustor.c
+               AllocArray.c
+               adjustor/AdjustorPool.c
+               ExecPage.c
+               Arena.c
+               Capability.c
+               CheckUnload.c
+               CheckVectorSupport.c
+               CloneStack.c
+               ClosureFlags.c
+               ClosureSize.c
+               Continuation.c
+               Disassembler.c
+               FileLock.c
+               ForeignExports.c
+               Globals.c
+               Hash.c
+               Heap.c
+               Hpc.c
+               HsFFI.c
+               Inlines.c
+               Interpreter.c
+               IOManager.c
+               LdvProfile.c
+               Libdw.c
+               LibdwPool.c
+               Linker.c
+               ReportMemoryMap.c
+               Messages.c
+               OldARMAtomic.c
+               PathUtils.c
+               Pool.c
+               Printer.c
+               ProfHeap.c
+               ProfilerReport.c
+               ProfilerReportJson.c
+               Profiling.c
+               IPE.c
+               Proftimer.c
+               RaiseAsync.c
+               RetainerProfile.c
+               RetainerSet.c
+               RtsAPI.c
+               RtsDllMain.c
+               RtsFlags.c
+               RtsMain.c
+               RtsMessages.c
+               RtsStartup.c
+               RtsSymbolInfo.c
+               RtsSymbols.c
+               RtsUtils.c
+               STM.c
+               Schedule.c
+               Sparks.c
+               SpinLock.c
+               StableName.c
+               StablePtr.c
+               StaticPtrTable.c
+               Stats.c
+               StgCRun.c
+               StgPrimFloat.c
+               Task.c
+               ThreadLabels.c
+               ThreadPaused.c
+               Threads.c
+               Ticky.c
+               Timer.c
+               TopHandler.c
+               Trace.c
+               TraverseHeap.c
+               TraverseHeapTest.c
+               TSANUtils.c
+               WSDeque.c
+               Weak.c
+               ZeroSlop.c
+               eventlog/EventLog.c
+               eventlog/EventLogWriter.c
+               hooks/FlagDefaults.c
+               hooks/LongGCSync.c
+               hooks/MallocFail.c
+               hooks/OnExit.c
+               hooks/OutOfHeap.c
+               hooks/StackOverflow.c
+               linker/CacheFlush.c
+               linker/Elf.c
+               linker/InitFini.c
+               linker/LoadArchive.c
+               linker/LoadNativeObjPosix.c
+               linker/M32Alloc.c
+               linker/MMap.c
+               linker/MachO.c
+               linker/macho/plt.c
+               linker/macho/plt_aarch64.c
+               linker/ProddableBlocks.c
+               linker/PEi386.c
+               linker/SymbolExtras.c
+               linker/elf_got.c
+               linker/elf_plt.c
+               linker/elf_plt_aarch64.c
+               linker/elf_plt_riscv64.c
+               linker/elf_plt_arm.c
+               linker/elf_reloc.c
+               linker/elf_reloc_aarch64.c
+               linker/elf_reloc_riscv64.c
+               linker/elf_tlsgd.c
+               linker/elf_util.c
+               sm/BlockAlloc.c
+               sm/CNF.c
+               sm/Compact.c
+               sm/Evac.c
+               sm/Evac_thr.c
+               sm/GC.c
+               sm/GCAux.c
+               sm/GCUtils.c
+               sm/MBlock.c
+               sm/MarkWeak.c
+               sm/NonMoving.c
+               sm/NonMovingAllocate.c
+               sm/NonMovingCensus.c
+               sm/NonMovingMark.c
+               sm/NonMovingScav.c
+               sm/NonMovingShortcut.c
+               sm/NonMovingSweep.c
+               sm/Sanity.c
+               sm/Scav.c
+               sm/Scav_thr.c
+               sm/Storage.c
+               sm/Sweep.c
                  -- I wish we had wildcards..., this would be:
                  -- *.c hooks/**/*.c sm/**/*.c eventlog/**/*.c linker/**/*.c
 
-      if os(windows)
-         c-sources: win32/AsyncMIO.c
-                    win32/AsyncWinIO.c
-                    win32/AwaitEvent.c
-                    win32/ConsoleHandler.c
-                    win32/GetEnv.c
-                    win32/GetTime.c
-                    win32/MIOManager.c
-                    win32/OSMem.c
-                    win32/OSThreads.c
-                    win32/ThrIOManager.c
-                    win32/Ticker.c
-                    win32/WorkQueue.c
-                    win32/veh_excn.c
-                    -- win32/**/*.c
-      elif arch(wasm32)
-        asm-sources: wasm/Wasm.S
-        c-sources: wasm/StgRun.c
-                   wasm/GetTime.c
-                   wasm/OSMem.c
-                   wasm/OSThreads.c
-                   wasm/JSFFI.c
-                   wasm/JSFFIGlobals.c
-                   posix/Select.c
-        cmm-sources: wasm/jsval.cmm
-                     wasm/blocker.cmm
-                     wasm/scheduler.cmm
+    if os(windows)
+       c-sources: win32/AsyncMIO.c
+                  win32/AsyncWinIO.c
+                  win32/AwaitEvent.c
+                  win32/ConsoleHandler.c
+                  win32/GetEnv.c
+                  win32/GetTime.c
+                  win32/MIOManager.c
+                  win32/OSMem.c
+                  win32/OSThreads.c
+                  win32/ThrIOManager.c
+                  win32/Ticker.c
+                  win32/WorkQueue.c
+                  win32/veh_excn.c
+    elif arch(wasm32)
+      asm-sources: wasm/Wasm.S
+      c-sources: wasm/StgRun.c
+                 wasm/GetTime.c
+                 wasm/OSMem.c
+                 wasm/OSThreads.c
+                 wasm/JSFFI.c
+                 wasm/JSFFIGlobals.c
+                 -- Note: Select.c included for wasm32
+                 posix/Select.c
+      cmm-sources: wasm/jsval.cmm
+                   wasm/blocker.cmm
+                   wasm/scheduler.cmm
+    -- Posix-like
+    else
+       c-sources: posix/GetEnv.c
+                  posix/GetTime.c
+                  posix/Ticker.c
+                  posix/OSMem.c
+                  posix/OSThreads.c
+                  posix/Select.c
+                  posix/Signals.c
+                  posix/TTY.c
+
+common rts-link-options
+    extra-libraries: ffi
+    extra-libraries-static: ffi
+
+    if os(linux)
+       extra-libraries: c
+    if flag(libm)
+       extra-libraries: m
+    if flag(librt)
+       extra-libraries: rt
+    if os(windows)
+       extra-libraries:
+          wsock32 gdi32 winmm
+          dbghelp
+          psapi
+       cpp-options: -D_WIN32_WINNT=0x06010000
+       cc-options: -D_WIN32_WINNT=0x06010000
+    if flag(need-atomic)
+       extra-libraries: atomic
+    if flag(libbfd)
+       extra-libraries: bfd iberty
+    if flag(libdw)
+       extra-libraries: elf dw
+    if flag(libnuma)
+       extra-libraries: numa
+    if flag(libzstd)
+       if flag(static-libzstd)
+          if os(darwin)
+             buildable: False
+          else
+             extra-libraries: :libzstd.a
+       else
+          extra-libraries: zstd
+
+    if os(osx)
+      ld-options: "-Wl,-search_paths_first"
+                  "-Wl,-undefined,dynamic_lookup"
+      if !arch(x86_64) && !arch(aarch64)
+         ld-options: -read_only_relocs warning
+
+                  "-Wl,-undefined,dynamic_lookup"
+      if !arch(x86_64) && !arch(aarch64)
+         ld-options: -read_only_relocs warning
+
+common rts-global-build-flags
+    ghc-options: -DCOMPILING_RTS
+    cpp-options: -DCOMPILING_RTS
+    if !flag(smp)
+       ghc-options: -DNOSMP
+       cpp-options: -DNOSMP
+    if flag(dynamic)
+       ghc-options: -DDYNAMIC
+       cpp-options: -DDYNAMIC
+    if flag(thread-sanitizer)
+      cc-options: -fsanitize=thread
+      ld-options: -fsanitize=thread
+
+common rts-debug-flags
+    ghc-options: -optc-DDEBUG
+    cpp-options: -DDEBUG -fno-omit-frame-pointer -g3 -O0
+
+common rts-threaded-flags
+    ghc-options: -DTHREADED_RTS
+    cpp-options: -DTHREADED_RTS
+
+-- the _main_ library needs to deal with all the _configure_ time stuff.
+library
+    ghc-options: -this-unit-id rts -ghcversion-file=include/ghcversion.h -optc-DFS_NAMESPACE=rts
+    cmm-options: -this-unit-id rts
+
+    autogen-includes:
+      ghcautoconf.h
+      ghcplatform.h
+      DerivedConstants.h
+      rts/EventLogConstants.h
+      rts/EventTypes.h
+
+    install-includes:
+      ghcautoconf.h
+      ghcplatform.h
+      DerivedConstants.h
+      rts/EventLogConstants.h
+      rts/EventTypes.h
+
+    install-includes:
+      -- Common headers for non-JS builds
+      Cmm.h HsFFI.h MachDeps.h Jumps.h Rts.h RtsAPI.h RtsSymbols.h Stg.h
+      ghcconfig.h ghcversion.h
+      rts/ghc_ffi.h
+      rts/Adjustor.h
+      rts/ExecPage.h
+      rts/BlockSignals.h
+      rts/Config.h
+      rts/Constants.h
+      rts/EventLogFormat.h
+      rts/EventLogWriter.h
+      rts/FileLock.h
+      rts/Flags.h
+      rts/ForeignExports.h
+      rts/GetTime.h
+      rts/Globals.h
+      rts/Hpc.h
+      rts/IOInterface.h
+      rts/Libdw.h
+      rts/LibdwPool.h
+      rts/Linker.h
+      rts/Main.h
+      rts/Messages.h
+      rts/NonMoving.h
+      rts/OSThreads.h
+      rts/Parallel.h
+      rts/PrimFloat.h
+      rts/Profiling.h
+      rts/IPE.h
+      rts/PosixSource.h
+      rts/Signals.h
+      rts/SpinLock.h
+      rts/StableName.h
+      rts/StablePtr.h
+      rts/StaticPtrTable.h
+      rts/TTY.h
+      rts/Threads.h
+      rts/Ticky.h
+      rts/Time.h
+      rts/Timer.h
+      rts/TSANUtils.h
+      rts/Types.h
+      rts/Utils.h
+      rts/prof/CCS.h
+      rts/prof/Heap.h
+      rts/prof/LDV.h
+      rts/storage/Block.h
+      rts/storage/ClosureMacros.h
+      rts/storage/Closures.h
+      rts/storage/Heap.h
+      rts/storage/HeapAlloc.h
+      rts/storage/GC.h
+      rts/storage/InfoTables.h
+      rts/storage/MBlock.h
+      rts/storage/TSO.h
+      stg/DLL.h
+      stg/MiscClosures.h
+      stg/Prim.h
+      stg/Regs.h
+      stg/SMP.h
+      stg/Ticky.h
+      stg/MachRegsForHost.h
+      stg/Types.h
+
+    include-dirs: include .
+
+    build-depends:
+      rts-headers,
+      rts-fs
+
+    if !arch(javascript)
+      -- FIXME: by virtue of being part of the rts main library, these do not get
+      -- the flags (debug, threaded, ...) as the sub libraries.  Thus we are
+      -- likely missing -DDEBUG, -DTHREADED_RTS, etc.
+      -- One solution to this would be to turn all of these into `.h` files, and
+      -- then have the `AutoApply.cmm` in `rts-c-sources-base` include them.  This
+      -- would mean they are included in the sublibraries which will in turn apply
+      -- the sublibrary specific (c)flags.
+      autogen-cmm-sources:
+        AutoApply.cmm
+        AutoApply_V16.cmm
+
+      if arch(x86_64)
+        cmm-sources:
+          Jumps_V32.cmm (-mavx2)
+          Jumps_V64.cmm (-mavx512f)
+        autogen-cmm-sources:
+          AutoApply_V32.cmm (-mavx2)
+          AutoApply_V64.cmm (-mavx512f)
       else
-         c-sources: posix/GetEnv.c
-                    posix/GetTime.c
-                    posix/Ticker.c
-                    posix/OSMem.c
-                    posix/OSThreads.c
-                    posix/Select.c
-                    posix/Signals.c
-                    posix/TTY.c
-                    -- ticker/*.c
-                    -- We don't want to compile posix/ticker/*.c, these will be #included
-                    -- from Ticker.c
+        cmm-sources:
+          Jumps_V32.cmm
+          Jumps_V64.cmm
+        autogen-cmm-sources:
+          AutoApply_V32.cmm
+          AutoApply_V64.cmm
+
+common ghcjs
+    import: rts-base-config
+
+    -- Keep original JS specific settings for the main library
+    include-dirs: include
+    js-sources:
+      js/config.js
+      js/structs.js
+      js/arith.js
+      js/compact.js
+      js/debug.js
+      js/enum.js
+      js/environment.js
+      js/eventlog.js
+      js/gc.js
+      js/goog.js
+      js/hscore.js
+      js/md5.js
+      js/mem.js
+      js/node-exports.js
+      js/object.js
+      js/profiling.js
+      js/rts.js
+      js/stableptr.js
+      js/staticpointer.js
+      js/stm.js
+      js/string.js
+      js/thread.js
+      js/unicode.js
+      js/verify.js
+      js/weak.js
+      js/globals.js
+      js/time.js
+
+    -- Add JS specific install-includes again
+    install-includes: HsFFI.h MachDeps.h Rts.h RtsAPI.h Stg.h
+                      ghcconfig.h
+                      ghcversion.h
+                      stg/MachRegsForHost.h
+                      stg/Types.h
+
+-- this is basiclly the "vanilla" version
+library nonthreaded-nodebug
+    if arch(javascript)
+      import: ghcjs
+    else
+      import: rts-base-config, rts-c-sources-base, rts-link-options, rts-global-build-flags
+
+    visibility: public
+
+    ghc-options: -optc-DRtsWay="v"
+
+
+library threaded-nodebug
+    import: rts-base-config, rts-c-sources-base, rts-link-options, rts-global-build-flags, rts-threaded-flags
+    visibility: public
+    build-depends: rts
+    if arch(javascript)
+      buildable: False
+
+library nonthreaded-debug
+    import: rts-base-config, rts-c-sources-base, rts-link-options, rts-global-build-flags, rts-debug-flags
+    visibility: public
+    build-depends: rts
+    if arch(javascript)
+      buildable: False
+
+library threaded-debug
+    import: rts-base-config, rts-c-sources-base, rts-link-options, rts-global-build-flags, rts-threaded-flags, rts-debug-flags
+    visibility: public
+    build-depends: rts
+    if arch(javascript)
+      buildable: False
 
 -- Note [Undefined symbols in the RTS]
 -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/utils/iserv/cbits/iservmain.c b/utils/ghc-iserv/cbits/iservmain.c
similarity index 100%
rename from utils/iserv/cbits/iservmain.c
rename to utils/ghc-iserv/cbits/iservmain.c
diff --git a/utils/iserv/iserv.cabal.in b/utils/ghc-iserv/ghc-iserv.cabal.in
similarity index 85%
rename from utils/iserv/iserv.cabal.in
rename to utils/ghc-iserv/ghc-iserv.cabal.in
index 51286873b819..b0a1e80f0e91 100644
--- a/utils/iserv/iserv.cabal.in
+++ b/utils/ghc-iserv/ghc-iserv.cabal.in
@@ -1,8 +1,8 @@
--- WARNING: iserv.cabal is automatically generated from iserv.cabal.in by
--- ../../configure.  Make sure you are editing iserv.cabal.in, not
--- iserv.cabal.
+-- WARNING: ghc-iserv.cabal is automatically generated from ghc-iserv.cabal.in
+-- by ../../configure.  Make sure you are editing ghc-iserv.cabal.in, not
+-- ghc-iserv.cabal.
 
-Name: iserv
+Name: ghc-iserv
 Version: @ProjectVersion@
 Copyright: XXX
 License: BSD3
@@ -23,7 +23,7 @@ Category: Development
 build-type: Simple
 cabal-version: >=1.10
 
-Executable iserv
+Executable ghc-iserv
     Default-Language: Haskell2010
     ghc-options: -no-hs-main
     Main-Is: Main.hs
diff --git a/utils/iserv/src/Main.hs b/utils/ghc-iserv/src/Main.hs
similarity index 100%
rename from utils/iserv/src/Main.hs
rename to utils/ghc-iserv/src/Main.hs