diff --git a/tools/mkconfig.c b/tools/mkconfig.c
index 28b0c0351f..4a64c7867c 100644
--- a/tools/mkconfig.c
+++ b/tools/mkconfig.c
@@ -98,8 +98,180 @@ int main(int argc, char **argv, char **envp)
   printf("/* config.h -- Autogenerated! Do not edit. */\n\n");
   printf("#ifndef __INCLUDE_NUTTX_CONFIG_H\n");
   printf("#define __INCLUDE_NUTTX_CONFIG_H\n\n");
+  printf("/* Architecture-specific options *************************/\n\n");
+
   generate_definitions(stream);
-  printf("\n#endif /* __INCLUDE_NUTTX_CONFIG_H */\n");
+
+  printf("\n/* Sanity Checks *****************************************/\n\n");
+  printf("/* If this is an NXFLAT, external build, then make sure that\n");
+  printf(" * NXFLAT support is enabled in the base code.\n");
+  printf(" */\n\n");
+  printf("#if defined(__NXFLAT__) && !defined(CONFIG_NXFLAT)\n");
+  printf("# error \"NXFLAT support not enabled in this configuration\"\n");
+  printf("#endif\n\n");
+  printf("/* NXFLAT requires PIC support in the TCBs. */\n\n");
+  printf("#if defined(CONFIG_NXFLAT)\n");
+  printf("# undef CONFIG_PIC\n");
+  printf("# define CONFIG_PIC 1\n");
+  printf("#endif\n\n");
+  printf("/* Binary format support is disabled if no binary formats are\n");
+  printf(" * configured (at present, NXFLAT is the only supported binary.\n");
+  printf(" * format).\n");
+  printf(" */\n\n");
+  printf("#if !defined(CONFIG_NXFLAT) && !defined(CONFIG_ELF) && !defined(CONFIG_BUILTIN)\n");
+  printf("# undef CONFIG_BINFMT_DISABLE\n");
+  printf("# define CONFIG_BINFMT_DISABLE 1\n");
+  printf("#endif\n\n");
+  printf("/* The correct way to disable RR scheduling is to set the\n");
+  printf(" * timeslice to zero.\n");
+  printf(" */\n\n");
+  printf("#ifndef CONFIG_RR_INTERVAL\n");
+  printf("# define CONFIG_RR_INTERVAL 0\n");
+  printf("#endif\n\n");
+  printf("/* The correct way to disable filesystem supuport is to set the number of\n");
+  printf(" * file descriptors to zero.\n");
+  printf(" */\n\n");
+  printf("#ifndef CONFIG_NFILE_DESCRIPTORS\n");
+  printf("# define CONFIG_NFILE_DESCRIPTORS 0\n");
+  printf("#endif\n\n");
+  printf("/* If a console is selected, then make sure that there are resources for\n");
+  printf(" * three file descriptors and, if any streams are selected, also for three\n");
+  printf(" * file streams.\n");
+  printf(" *\n");
+  printf(" * CONFIG_DEV_CONSOLE means that a builtin console device exists at /dev/console\n");
+  printf(" * and can be opened during boot-up.  Other consoles, such as USB consoles, may\n");
+  printf(" * not exist at boot-upand have to be handled in a different way.  Three file\n");
+  printf(" * descriptors and three file streams are still needed.\n");
+  printf(" */\n\n");
+  printf("#if defined(CONFIG_DEV_CONSOLE) || defined(CONFIG_CDCACM_CONSOLE) || \\\n");
+  printf("    defined(CONFIG_PL2303_CONSOLE)\n");
+  printf("# if CONFIG_NFILE_DESCRIPTORS < 3\n");
+  printf("#   undef CONFIG_NFILE_DESCRIPTORS\n");
+  printf("#   define CONFIG_NFILE_DESCRIPTORS 3\n");
+  printf("# endif\n\n");
+  printf("# if CONFIG_NFILE_STREAMS > 0 && CONFIG_NFILE_STREAMS < 3\n");
+  printf("#  undef CONFIG_NFILE_STREAMS\n");
+  printf("#  define CONFIG_NFILE_STREAMS 3\n");
+  printf("# endif\n\n");
+  printf("/* If no console is selected, then disable all builtin console devices */\n\n");
+  printf("#else\n");
+  printf("#  undef CONFIG_DEV_LOWCONSOLE\n");
+  printf("#  undef CONFIG_RAMLOG_CONSOLE\n");
+  printf("#endif\n\n");
+  printf("/* If priority inheritance is disabled, then do not allocate any\n");
+  printf(" * associated resources.\n");
+  printf(" */\n\n");
+  printf("#if !defined(CONFIG_PRIORITY_INHERITANCE) || !defined(CONFIG_SEM_PREALLOCHOLDERS)\n");
+  printf("# undef CONFIG_SEM_PREALLOCHOLDERS\n");
+  printf("# define CONFIG_SEM_PREALLOCHOLDERS 0\n");
+  printf("#endif\n\n");
+  printf("#if !defined(CONFIG_PRIORITY_INHERITANCE) || !defined(CONFIG_SEM_NNESTPRIO)\n");
+  printf("# undef CONFIG_SEM_NNESTPRIO\n");
+  printf("# define CONFIG_SEM_NNESTPRIO 0\n");
+  printf("#endif\n\n");
+  printf("/* If no file descriptors are configured, then make certain no\n");
+  printf(" * streams are configured either.\n");
+  printf(" */\n\n");
+  printf("#if CONFIG_NFILE_DESCRIPTORS == 0\n");
+  printf("# undef CONFIG_NFILE_STREAMS\n");
+  printf("# define CONFIG_NFILE_STREAMS 0\n");
+  printf("#endif\n\n");
+  printf("/* There must be at least one memory region. */\n\n");
+  printf("#ifndef CONFIG_MM_REGIONS\n");
+  printf("# define CONFIG_MM_REGIONS 1\n");
+  printf("#endif\n\n");
+  printf("/* If the end of RAM is not specified then it is assumed to be the beginning\n");
+  printf(" * of RAM plus the RAM size.\n");
+  printf(" */\n\n");
+  printf("#ifndef CONFIG_RAM_END\n");
+  printf("# define CONFIG_RAM_END (CONFIG_RAM_START+CONFIG_RAM_SIZE)\n");
+  printf("#endif\n\n");
+  printf("#ifndef CONFIG_RAM_VEND\n");
+  printf("# define CONFIG_RAM_VEND (CONFIG_RAM_VSTART+CONFIG_RAM_SIZE)\n");
+  printf("#endif\n\n");
+  printf("/* If the end of FLASH is not specified then it is assumed to be the beginning\n");
+  printf(" * of FLASH plus the FLASH size.\n");
+  printf(" */\n\n");
+  printf("#ifndef CONFIG_FLASH_END\n");
+  printf("# define CONFIG_FLASH_END (CONFIG_FLASH_START+CONFIG_FLASH_SIZE)\n");
+  printf("#endif\n\n");
+  printf("/* If no file streams are configured, then make certain that buffered I/O\n");
+  printf(" * support is disabled\n");
+  printf(" */\n\n");
+  printf("#if CONFIG_NFILE_STREAMS == 0\n");
+  printf("# undef CONFIG_STDIO_BUFFER_SIZE\n");
+  printf("# define CONFIG_STDIO_BUFFER_SIZE 0\n");
+  printf("#endif\n\n");
+  printf("/* If no standard C buffered I/O is not supported, then line-oriented buffering\n");
+  printf(" * cannot be supported.\n");
+  printf(" */\n\n");
+  printf("#if CONFIG_STDIO_BUFFER_SIZE == 0\n");
+  printf("# undef CONFIG_STDIO_LINEBUFFER\n");
+  printf("#endif\n\n");
+  printf("/* If the maximum message size is zero, then we assume that message queues\n");
+  printf(" * support should be disabled\n");
+  printf(" */\n\n");
+  printf("#if !defined(CONFIG_MQ_MAXMSGSIZE) || defined(CONFIG_DISABLE_MQUEUE)\n");
+  printf("# undef CONFIG_MQ_MAXMSGSIZE\n");
+  printf("# define CONFIG_MQ_MAXMSGSIZE 0\n");
+  printf("#endif\n\n");
+  printf("#if CONFIG_MQ_MAXMSGSIZE <= 0 && !defined(CONFIG_DISABLE_MQUEUE)\n");
+  printf("# define CONFIG_DISABLE_MQUEUE 1\n");
+  printf("#endif\n\n");
+  printf("/* If mountpoint support in not included, then no filesystem can be supported */\n\n");
+  printf("#ifdef CONFIG_DISABLE_MOUNTPOINT\n");
+  printf("# undef CONFIG_FS_FAT\n");
+  printf("# undef CONFIG_FS_ROMFS\n");
+  printf("# undef CONFIG_FS_NXFFS\n");
+  printf("# undef CONFIG_FS_SMARTFS\n");
+  printf("# undef CONFIG_FS_BINFS\n");
+  printf("# undef CONFIG_NFS\n");
+  printf("#endif\n\n");
+  printf("/* There can be no network support with no socket descriptors */\n\n");
+  printf("#if CONFIG_NSOCKET_DESCRIPTORS <= 0\n");
+  printf("# undef CONFIG_NET\n");
+  printf("#endif\n\n");
+  printf("/* Conversely, if there is no network support, there is no need for\n");
+  printf(" * socket descriptors\n");
+  printf(" */\n\n");
+  printf("#ifndef CONFIG_NET\n");
+  printf("# undef CONFIG_NSOCKET_DESCRIPTORS\n");
+  printf("# define CONFIG_NSOCKET_DESCRIPTORS 0\n");
+  printf("#endif\n\n");
+  printf("/* Protocol support can only be provided on top of basic network support */\n\n");
+  printf("#ifndef CONFIG_NET\n");
+  printf("# undef CONFIG_NET_TCP\n");
+  printf("# undef CONFIG_NET_UDP\n");
+  printf("# undef CONFIG_NET_ICMP\n");
+  printf("#endif\n\n");
+  printf("/* NFS client can only be provided on top of UDP network support */\n\n");
+  printf("#if !defined(CONFIG_NET) || !defined(CONFIG_NET_UDP)\n");
+  printf("# undef CONFIG_NFS\n");
+  printf("#endif\n\n");
+  printf("/* Verbose debug and sub-system debug only make sense if debug is enabled */\n\n");
+  printf("#ifndef CONFIG_DEBUG\n");
+  printf("# undef CONFIG_DEBUG_VERBOSE\n");
+  printf("# undef CONFIG_DEBUG_SCHED\n");
+  printf("# undef CONFIG_DEBUG_MM\n");
+  printf("# undef CONFIG_DEBUG_PAGING\n");
+  printf("# undef CONFIG_DEBUG_DMA\n");
+  printf("# undef CONFIG_DEBUG_FS\n");
+  printf("# undef CONFIG_DEBUG_LIB\n");
+  printf("# undef CONFIG_DEBUG_BINFMT\n");
+  printf("# undef CONFIG_DEBUG_NET\n");
+  printf("# undef CONFIG_DEBUG_USB\n");
+  printf("# undef CONFIG_DEBUG_GRAPHICS\n");
+  printf("# undef CONFIG_DEBUG_GPIO\n");
+  printf("# undef CONFIG_DEBUG_SPI\n");
+  printf("# undef CONFIG_DEBUG_HEAP\n");
+  printf("#endif\n\n");
+  printf("/* User entry point. This is provided as a fall-back to keep compatibility\n");
+  printf(" * with existing code, for builds which do not define CONFIG_USER_ENTRYPOINT.\n");
+  printf(" */\n\n");
+  printf("#ifndef CONFIG_USER_ENTRYPOINT\n");
+  printf("# define CONFIG_USER_ENTRYPOINT main\n");
+  printf("#endif\n\n");
+  printf("#endif /* __INCLUDE_NUTTX_CONFIG_H */\n");
   fclose(stream);
 
   /* Exit (without bothering to clean up allocations) */