diff --git a/libraries/AP_Filesystem/AP_Filesystem.cpp b/libraries/AP_Filesystem/AP_Filesystem.cpp
index 09bfcd05a7..240e95e41d 100644
--- a/libraries/AP_Filesystem/AP_Filesystem.cpp
+++ b/libraries/AP_Filesystem/AP_Filesystem.cpp
@@ -16,6 +16,9 @@
 #include "AP_Filesystem.h"
 
 #include "AP_Filesystem_config.h"
+
+#if AP_FILESYSTEM_FILE_READING_ENABLED
+
 #include <AP_HAL/HAL.h>
 #include <AP_HAL/Util.h>
 #include <AP_Math/AP_Math.h>
@@ -202,7 +205,9 @@ AP_Filesystem::DirHandle *AP_Filesystem::opendir(const char *pathname)
         (strlen(pathname) == 1 && pathname[0] == '/')) {
         virtual_dirent.backend_ofs = 0;
         virtual_dirent.d_off = 0;
+#if AP_FILESYSTEM_HAVE_DIRENT_DTYPE
         virtual_dirent.de.d_type = DT_DIR;
+#endif
     } else {
         virtual_dirent.backend_ofs = 255;
     }
@@ -430,3 +435,4 @@ AP_Filesystem &FS()
 }
 }
 
+#endif // AP_FILESYSTEM_FILE_READING_ENABLED
diff --git a/libraries/AP_Filesystem/AP_Filesystem.h b/libraries/AP_Filesystem/AP_Filesystem.h
index c2bd20e765..cc8619ca52 100644
--- a/libraries/AP_Filesystem/AP_Filesystem.h
+++ b/libraries/AP_Filesystem/AP_Filesystem.h
@@ -54,7 +54,7 @@ struct dirent {
 #define AP_FILESYSTEM_FORMAT_ENABLED 1
 #endif
 
-#if CONFIG_HAL_BOARD == HAL_BOARD_LINUX || CONFIG_HAL_BOARD == HAL_BOARD_SITL
+#if CONFIG_HAL_BOARD == HAL_BOARD_LINUX || CONFIG_HAL_BOARD == HAL_BOARD_SITL || CONFIG_HAL_BOARD == HAL_BOARD_QURT
 #include "AP_Filesystem_posix.h"
 #endif
 
diff --git a/libraries/AP_Filesystem/AP_Filesystem_ROMFS.cpp b/libraries/AP_Filesystem/AP_Filesystem_ROMFS.cpp
index eb562694a8..f481d87255 100644
--- a/libraries/AP_Filesystem/AP_Filesystem_ROMFS.cpp
+++ b/libraries/AP_Filesystem/AP_Filesystem_ROMFS.cpp
@@ -192,11 +192,14 @@ struct dirent *AP_Filesystem_ROMFS::readdir(void *dirp)
     const char* slash = strchr(name, '/');
     if (slash == nullptr) {
         // File
+#if AP_FILESYSTEM_HAVE_DIRENT_DTYPE
         dir[idx].de.d_type = DT_REG;
-
+#endif
     } else {
         // Directory
+#if AP_FILESYSTEM_HAVE_DIRENT_DTYPE
         dir[idx].de.d_type = DT_DIR;
+#endif
 
         // Add null termination after directory name
         const size_t index = slash - name;
diff --git a/libraries/AP_Filesystem/AP_Filesystem_Sys.cpp b/libraries/AP_Filesystem/AP_Filesystem_Sys.cpp
index 7efa34db0b..5063267c04 100644
--- a/libraries/AP_Filesystem/AP_Filesystem_Sys.cpp
+++ b/libraries/AP_Filesystem/AP_Filesystem_Sys.cpp
@@ -244,7 +244,9 @@ struct dirent *AP_Filesystem_Sys::readdir(void *dirp)
         // we have reached end of list
         return nullptr;
     }
+#if AP_FILESYSTEM_HAVE_DIRENT_DTYPE
     dtracker->curr_file.d_type = DT_REG;
+#endif
     size_t max_length = ARRAY_SIZE(dtracker->curr_file.d_name);
     strncpy_noterm(dtracker->curr_file.d_name, sysfs_file_list[dtracker->file_offset].name, max_length);
     dtracker->file_offset++;
diff --git a/libraries/AP_Filesystem/AP_Filesystem_config.h b/libraries/AP_Filesystem/AP_Filesystem_config.h
index e96b33d105..93e307ed7e 100644
--- a/libraries/AP_Filesystem/AP_Filesystem_config.h
+++ b/libraries/AP_Filesystem/AP_Filesystem_config.h
@@ -23,7 +23,7 @@
 #endif
 
 #ifndef AP_FILESYSTEM_POSIX_ENABLED
-#define AP_FILESYSTEM_POSIX_ENABLED (CONFIG_HAL_BOARD == HAL_BOARD_SITL || CONFIG_HAL_BOARD == HAL_BOARD_LINUX)
+#define AP_FILESYSTEM_POSIX_ENABLED (CONFIG_HAL_BOARD == HAL_BOARD_SITL || CONFIG_HAL_BOARD == HAL_BOARD_LINUX || CONFIG_HAL_BOARD == HAL_BOARD_QURT)
 #endif
 
 #ifndef AP_FILESYSTEM_ROMFS_ENABLED
@@ -34,6 +34,11 @@
 #define AP_FILESYSTEM_SYS_ENABLED 1
 #endif
 
+#ifndef AP_FILESYSTEM_POSIX_MAP_FILENAME_ALLOC
+// this requires AP_FILESYSTEM_POSIX_MAP_FILENAME_BASEDIR
+#define AP_FILESYSTEM_POSIX_MAP_FILENAME_ALLOC 0
+#endif
+
 // AP_FILESYSTEM_FILE_WRITING_ENABLED is true if you could expect to
 // be able to open and write a non-virtual file.  Notably this
 // excludes virtual files like SYSFS, and the magic param/mission
@@ -47,7 +52,7 @@
 // be able to open and read a non-virtual file.  Notably this excludes
 // virtual files like SYSFS, and the magic param/mission upload targets.
 #ifndef AP_FILESYSTEM_FILE_READING_ENABLED
-#define AP_FILESYSTEM_FILE_READING_ENABLED (AP_FILESYSTEM_FILE_WRITING_ENABLED || AP_FILESYSTEM_ROMFS_ENABLED)
+#define AP_FILESYSTEM_FILE_READING_ENABLED (AP_FILESYSTEM_FILE_WRITING_ENABLED || AP_FILESYSTEM_ROMFS_ENABLED || AP_FILESYSTEM_SYS_ENABLED || AP_FILESYSTEM_PARAM_ENABLED)
 #endif
 
 #ifndef AP_FILESYSTEM_SYS_FLASH_ENABLED
diff --git a/libraries/AP_Filesystem/AP_Filesystem_posix.cpp b/libraries/AP_Filesystem/AP_Filesystem_posix.cpp
index 5a61690534..8e6e49595e 100644
--- a/libraries/AP_Filesystem/AP_Filesystem_posix.cpp
+++ b/libraries/AP_Filesystem/AP_Filesystem_posix.cpp
@@ -26,18 +26,29 @@
 
 #if defined(__APPLE__)
 #include <sys/mount.h>
-#else
+#elif CONFIG_HAL_BOARD != HAL_BOARD_QURT
 #include <sys/vfs.h>
 #endif
+
+#if AP_FILESYSTEM_POSIX_HAVE_UTIME
 #include <utime.h>
+#endif
 
 extern const AP_HAL::HAL& hal;
 
 /*
-  map a filename for SITL so operations are relative to the current directory
+  map a filename so operations are relative to the current directory if needed
  */
 static const char *map_filename(const char *fname)
 {
+#if AP_FILESYSTEM_POSIX_MAP_FILENAME_ALLOC
+    // this system needs to add a prefix to the filename, which means
+    // memory allocation. This is needed for QURT which lacks chdir()
+    char *fname2 = nullptr;
+    asprintf(&fname2, "%s/%s", AP_FILESYSTEM_POSIX_MAP_FILENAME_BASEDIR, fname);
+    return fname2;
+#else
+
 #if CONFIG_HAL_BOARD == HAL_BOARD_SITL && !APM_BUILD_TYPE(APM_BUILD_Replay)
     // on SITL only allow paths under subdirectory. Users can still
     // escape with .. if they want to
@@ -50,6 +61,14 @@ static const char *map_filename(const char *fname)
 #endif
     // on Linux allow original name
     return fname;
+#endif // AP_FILESYSTEM_POSIX_MAP_FILENAME_ALLOC
+}
+
+static void map_filename_free(const char *fname)
+{
+#if AP_FILESYSTEM_POSIX_MAP_FILENAME_ALLOC
+    ::free(const_cast<char*>(fname));
+#endif
 }
 
 int AP_Filesystem_Posix::open(const char *fname, int flags, bool allow_absolute_paths)
@@ -62,10 +81,18 @@ int AP_Filesystem_Posix::open(const char *fname, int flags, bool allow_absolute_
     if (::stat(fname, &st) == 0 &&
         ((st.st_mode & S_IFMT) != S_IFREG && (st.st_mode & S_IFMT) != S_IFLNK)) {
         // only allow links and files
+        if (!allow_absolute_paths) {
+            map_filename_free(fname);
+        }
         return -1;
     }
+
     // we automatically add O_CLOEXEC as we always want it for ArduPilot FS usage
-    return ::open(fname, flags | O_CLOEXEC, 0644);
+    auto ret = ::open(fname, flags | O_CLOEXEC, 0644);
+    if (!allow_absolute_paths) {
+        map_filename_free(fname);
+    }
+    return ret;
 }
 
 int AP_Filesystem_Posix::close(int fd)
@@ -88,8 +115,14 @@ int32_t AP_Filesystem_Posix::write(int fd, const void *buf, uint32_t count)
 
 int AP_Filesystem_Posix::fsync(int fd)
 {
+#if AP_FILESYSTEM_POSIX_HAVE_FSYNC
     FS_CHECK_ALLOWED(-1);
     return ::fsync(fd);
+#else
+    // we have to pass success here as otherwise it is assumed to be
+    // failed IO and the caller may close the fd and give up
+    return 0;
+#endif
 }
 
 int32_t AP_Filesystem_Posix::lseek(int fd, int32_t offset, int seek_from)
@@ -102,7 +135,9 @@ int AP_Filesystem_Posix::stat(const char *pathname, struct stat *stbuf)
 {
     FS_CHECK_ALLOWED(-1);
     pathname = map_filename(pathname);
-    return ::stat(pathname, stbuf);
+    auto ret = ::stat(pathname, stbuf);
+    map_filename_free(pathname);
+    return ret;
 }
 
 int AP_Filesystem_Posix::unlink(const char *pathname)
@@ -111,10 +146,11 @@ int AP_Filesystem_Posix::unlink(const char *pathname)
     pathname = map_filename(pathname);
     // we match the FATFS interface and use unlink
     // for both files and directories
-    int ret = ::rmdir(pathname);
+    int ret = ::rmdir(const_cast<char*>(pathname));
     if (ret == -1) {
         ret = ::unlink(pathname);
     }
+    map_filename_free(pathname);
     return ret;
 }
 
@@ -122,14 +158,18 @@ int AP_Filesystem_Posix::mkdir(const char *pathname)
 {
     FS_CHECK_ALLOWED(-1);
     pathname = map_filename(pathname);
-    return ::mkdir(pathname, 0775);
+    auto ret = ::mkdir(const_cast<char*>(pathname), 0775);
+    map_filename_free(pathname);
+    return ret;
 }
 
 void *AP_Filesystem_Posix::opendir(const char *pathname)
 {
     FS_CHECK_ALLOWED(nullptr);
     pathname = map_filename(pathname);
-    return (void*)::opendir(pathname);
+    auto *ret = (void*)::opendir(pathname);
+    map_filename_free(pathname);
+    return ret;
 }
 
 struct dirent *AP_Filesystem_Posix::readdir(void *dirp)
@@ -149,31 +189,46 @@ int AP_Filesystem_Posix::rename(const char *oldpath, const char *newpath)
     FS_CHECK_ALLOWED(-1);
     oldpath = map_filename(oldpath);
     newpath = map_filename(newpath);
-    return ::rename(oldpath, newpath);
+    auto ret = ::rename(oldpath, newpath);
+    map_filename_free(oldpath);
+    map_filename_free(newpath);
+    return ret;
 }
 
 // return free disk space in bytes
 int64_t AP_Filesystem_Posix::disk_free(const char *path)
 {
+#if AP_FILESYSTEM_POSIX_HAVE_STATFS
     FS_CHECK_ALLOWED(-1);
     path = map_filename(path);
     struct statfs stats;
     if (::statfs(path, &stats) < 0) {
+        map_filename_free(path);
         return -1;
     }
+    map_filename_free(path);
     return (((int64_t)stats.f_bavail) * stats.f_bsize);
+#else
+    return -1;
+#endif
 }
 
 // return total disk space in bytes
 int64_t AP_Filesystem_Posix::disk_space(const char *path)
 {
+#if AP_FILESYSTEM_POSIX_HAVE_STATFS
     FS_CHECK_ALLOWED(-1);
     path = map_filename(path);
     struct statfs stats;
     if (::statfs(path, &stats) < 0) {
+        map_filename_free(path);
         return -1;
     }
+    map_filename_free(path);
     return (((int64_t)stats.f_blocks) * stats.f_bsize);
+#else
+    return -1;
+#endif
 }
 
 
@@ -182,13 +237,19 @@ int64_t AP_Filesystem_Posix::disk_space(const char *path)
  */
 bool AP_Filesystem_Posix::set_mtime(const char *filename, const uint32_t mtime_sec)
 {
+#if AP_FILESYSTEM_POSIX_HAVE_UTIME
     FS_CHECK_ALLOWED(false);
     filename = map_filename(filename);
     struct utimbuf times {};
     times.actime = mtime_sec;
     times.modtime = mtime_sec;
 
-    return utime(filename, &times) == 0;
+    auto ret = utime(filename, &times) == 0;
+    map_filename_free(filename);
+    return ret;
+#else
+    return false;
+#endif
 }
 
 #endif  // AP_FILESYSTEM_POSIX_ENABLED
diff --git a/libraries/AP_Filesystem/AP_Filesystem_posix.h b/libraries/AP_Filesystem/AP_Filesystem_posix.h
index e44764213a..2e291db70f 100644
--- a/libraries/AP_Filesystem/AP_Filesystem_posix.h
+++ b/libraries/AP_Filesystem/AP_Filesystem_posix.h
@@ -29,6 +29,22 @@
 #include <errno.h>
 #include "AP_Filesystem_backend.h"
 
+#ifndef AP_FILESYSTEM_POSIX_HAVE_UTIME
+#define AP_FILESYSTEM_POSIX_HAVE_UTIME 1
+#endif
+
+#ifndef AP_FILESYSTEM_POSIX_HAVE_FSYNC
+#define AP_FILESYSTEM_POSIX_HAVE_FSYNC 1
+#endif
+
+#ifndef AP_FILESYSTEM_POSIX_HAVE_STATFS
+#define AP_FILESYSTEM_POSIX_HAVE_STATFS 1
+#endif
+
+#ifndef O_CLOEXEC
+#define O_CLOEXEC 0
+#endif
+
 class AP_Filesystem_Posix : public AP_Filesystem_Backend
 {
 public:
diff --git a/libraries/AP_Filesystem/posix_compat.h b/libraries/AP_Filesystem/posix_compat.h
index 4ccf56b5c5..ce95a8c557 100644
--- a/libraries/AP_Filesystem/posix_compat.h
+++ b/libraries/AP_Filesystem/posix_compat.h
@@ -78,6 +78,12 @@ char *tmpnam(char s[L_tmpnam]);
 #endif
 
 #define FILE APFS_FILE
+
+#ifndef __cplusplus
+/*
+  only redefine posix functions for C code (eg. lua).
+  for C++ use the AP_Filsystem APIs
+*/
 #define fopen(p,m) apfs_fopen(p,m)
 #define fprintf(stream, format, args...) apfs_fprintf(stream, format, ##args)
 #define fflush(s) apfs_fflush(s)
@@ -101,6 +107,7 @@ char *tmpnam(char s[L_tmpnam]);
 #define remove(pathname) apfs_remove(pathname)
 int sprintf(char *str, const char *format, ...);
 #endif
+#endif // __cplusplus
 
 #ifdef __cplusplus
 }