Merge tag 'v1.9.1' into parse-bytecode

Fixes for stmhal USB mass storage, lwIP bindings and VFS regressions

This release provides an important fix for the USB mass storage device in
the stmhal port by implementing the SCSI SYNCHRONIZE_CACHE command, which
is now require by some Operating Systems.  There are also fixes for the
lwIP bindings to improve non-blocking sockets and error codes.  The VFS has
some regressions fixed including the ability to statvfs the root.

All changes are listed below.

py core:
- modbuiltins: add core-provided version of input() function
- objstr: catch case of negative "maxsplit" arg to str.rsplit()
- persistentcode: allow to compile with complex numbers disabled
- objstr: allow to compile with obj-repr D, and unicode disabled
- modsys: allow to compile with obj-repr D and PY_ATTRTUPLE disabled
- provide mp_decode_uint_skip() to help reduce stack usage
- makeqstrdefs.py: make script run correctly with Python 2.6
- objstringio: if created from immutable object, follow copy on write policy

extmod:
- modlwip: connect: for non-blocking mode, return EINPROGRESS
- modlwip: fix error codes for duplicate calls to connect()
- modlwip: accept: fix error code for non-blocking mode
- vfs: allow to statvfs the root directory
- vfs: allow "buffering" and "encoding" args to VFS's open()
- modframebuf: fix signed/unsigned comparison pendantic warning

lib:
- libm: use isfinite instead of finitef, for C99 compatibility
- utils/interrupt_char: remove support for KBD_EXCEPTION disabled

tests:
- basics/string_rsplit: add tests for negative "maxsplit" argument
- float: convert "sys.exit()" to "raise SystemExit"
- float/builtin_float_minmax: PEP8 fixes
- basics: convert "sys.exit()" to "raise SystemExit"
- convert remaining "sys.exit()" to "raise SystemExit"

unix port:
- convert to use core-provided version of built-in import()
- Makefile: replace references to make with $(MAKE)

windows port:
- convert to use core-provided version of built-in import()

qemu-arm port:
- Makefile: adjust object-file lists to get correct dependencies
- enable micropython.mem_*() functions to allow more tests

stmhal port:
- boards: enable DAC for NUCLEO_F767ZI board
- add support for NUCLEO_F446RE board
- pass USB handler as parameter to allow more than one USB handler
- usb: use local USB handler variable in Start-of-Frame handler
- usb: make state for USB device private to top-level USB driver
- usbdev: for MSC implement SCSI SYNCHRONIZE_CACHE command
- convert from using stmhal's input() to core provided version

cc3200 port:
- convert from using stmhal's input() to core provided version

teensy port:
- convert from using stmhal's input() to core provided version

esp8266 port:
- Makefile: replace references to make with $(MAKE)
- Makefile: add clean-modules target
- convert from using stmhal's input() to core provided version

zephyr port:
- modusocket: getaddrinfo: Fix mp_obj_len() usage
- define MICROPY_PY_SYS_PLATFORM (to "zephyr")
- machine_pin: use native Zephyr types for Zephyr API calls

docs:
- machine.Pin: remove out_value() method
- machine.Pin: add on() and off() methods
- esp8266: consistently replace Pin.high/low methods with .on/off
- esp8266/quickref: polish Pin.on()/off() examples
- network: move confusingly-named cc3200 Server class to its reference
- uos: deconditionalize, remove minor port-specific details
- uos: move cc3200 port legacy VFS mounting functions to its ref doc
- machine: sort machine classes in logical order, not alphabetically
- network: first step to describe standard network class interface

examples:
- embedding: use core-provided KeyboardInterrupt object

62 files changed, 88 insertions, 137 deletions

diff --git a/tests/extmod/btree1.py b/tests/extmod/btree1.py
index 2127554db4..59638ef0a4 100644
--- a/tests/extmod/btree1.py
+++ b/tests/extmod/btree1.py
@@ -4,8 +4,7 @@ try:
     import uerrno
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 #f = open("_test.db", "w+b")
 f = uio.BytesIO()
diff --git a/tests/extmod/framebuf1.py b/tests/extmod/framebuf1.py
index 990b0b120d..2c13665228 100644
--- a/tests/extmod/framebuf1.py
+++ b/tests/extmod/framebuf1.py
@@ -2,8 +2,7 @@ try:
     import framebuf
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 w = 5
 h = 16
diff --git a/tests/extmod/framebuf16.py b/tests/extmod/framebuf16.py
index 3aa1d34def..fe81f7f93f 100644
--- a/tests/extmod/framebuf16.py
+++ b/tests/extmod/framebuf16.py
@@ -2,8 +2,7 @@ try:
     import framebuf
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 def printbuf():
     print("--8<--")
diff --git a/tests/extmod/framebuf4.py b/tests/extmod/framebuf4.py
index 641f5bfc59..8358fa55b9 100644
--- a/tests/extmod/framebuf4.py
+++ b/tests/extmod/framebuf4.py
@@ -2,8 +2,7 @@ try:
     import framebuf
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 def printbuf():
     print("--8<--")
diff --git a/tests/extmod/machine1.py b/tests/extmod/machine1.py
index e0c5611684..6ff38cc051 100644
--- a/tests/extmod/machine1.py
+++ b/tests/extmod/machine1.py
@@ -8,8 +8,7 @@ try:
     machine.mem8
 except:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 print(machine.mem8)
 
diff --git a/tests/extmod/machine_pinbase.py b/tests/extmod/machine_pinbase.py
index 5e82823ec0..e91775504d 100644
--- a/tests/extmod/machine_pinbase.py
+++ b/tests/extmod/machine_pinbase.py
@@ -6,8 +6,7 @@ try:
     machine.PinBase
 except AttributeError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 
 class MyPin(machine.PinBase):
diff --git a/tests/extmod/machine_pulse.py b/tests/extmod/machine_pulse.py
index 6491b54090..d525974e0c 100644
--- a/tests/extmod/machine_pulse.py
+++ b/tests/extmod/machine_pulse.py
@@ -7,8 +7,7 @@ try:
     machine.time_pulse_us
 except AttributeError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 
 class ConstPin(machine.PinBase):
diff --git a/tests/extmod/machine_signal.py b/tests/extmod/machine_signal.py
index 96b8f43c73..53f4f5890c 100644
--- a/tests/extmod/machine_signal.py
+++ b/tests/extmod/machine_signal.py
@@ -9,8 +9,7 @@ try:
     machine.Signal
 except AttributeError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 class Pin(machine.PinBase):
     def __init__(self):
diff --git a/tests/extmod/time_ms_us.py b/tests/extmod/time_ms_us.py
index 2078f1bb53..31f07d31ba 100644
--- a/tests/extmod/time_ms_us.py
+++ b/tests/extmod/time_ms_us.py
@@ -1,10 +1,9 @@
-import sys
 import utime
 try:
     utime.sleep_ms
 except AttributeError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 utime.sleep_ms(1)
 utime.sleep_us(1)
diff --git a/tests/extmod/ubinascii_a2b_base64.py b/tests/extmod/ubinascii_a2b_base64.py
index 58eb0b50b6..b35f265910 100644
--- a/tests/extmod/ubinascii_a2b_base64.py
+++ b/tests/extmod/ubinascii_a2b_base64.py
@@ -4,9 +4,8 @@ try:
     except ImportError:
         import binascii
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(binascii.a2b_base64(b''))
 print(binascii.a2b_base64(b'Zg=='))
diff --git a/tests/extmod/ubinascii_b2a_base64.py b/tests/extmod/ubinascii_b2a_base64.py
index 1c0c30311d..f4bb69fe0c 100644
--- a/tests/extmod/ubinascii_b2a_base64.py
+++ b/tests/extmod/ubinascii_b2a_base64.py
@@ -4,9 +4,8 @@ try:
     except ImportError:
         import binascii
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(binascii.b2a_base64(b''))
 print(binascii.b2a_base64(b'f'))
diff --git a/tests/extmod/ubinascii_crc32.py b/tests/extmod/ubinascii_crc32.py
index b82c44d6bf..89664a9b36 100644
--- a/tests/extmod/ubinascii_crc32.py
+++ b/tests/extmod/ubinascii_crc32.py
@@ -4,16 +4,14 @@ try:
     except ImportError:
         import binascii
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 try:
     binascii.crc32
 except AttributeError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 print(hex(binascii.crc32(b'The quick brown fox jumps over the lazy dog')))
 print(hex(binascii.crc32(b'\x00' * 32)))
diff --git a/tests/extmod/ubinascii_hexlify.py b/tests/extmod/ubinascii_hexlify.py
index 5d70bda96d..bc99287476 100644
--- a/tests/extmod/ubinascii_hexlify.py
+++ b/tests/extmod/ubinascii_hexlify.py
@@ -4,9 +4,8 @@ try:
     except ImportError:
         import binascii
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(binascii.hexlify(b'\x00\x01\x02\x03\x04\x05\x06\x07'))
 print(binascii.hexlify(b'\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f'))
diff --git a/tests/extmod/ubinascii_micropython.py b/tests/extmod/ubinascii_micropython.py
index 96f566bd14..a4c00a2cb8 100644
--- a/tests/extmod/ubinascii_micropython.py
+++ b/tests/extmod/ubinascii_micropython.py
@@ -4,9 +4,8 @@ try:
     except ImportError:
         import binascii
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # two arguments supported in uPy but not CPython
 a = binascii.hexlify(b'123', ':')
diff --git a/tests/extmod/ubinascii_unhexlify.py b/tests/extmod/ubinascii_unhexlify.py
index e669789ba8..865abfe3a8 100644
--- a/tests/extmod/ubinascii_unhexlify.py
+++ b/tests/extmod/ubinascii_unhexlify.py
@@ -4,9 +4,8 @@ try:
     except ImportError:
         import binascii
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(binascii.unhexlify(b'0001020304050607'))
 print(binascii.unhexlify(b'08090a0b0c0d0e0f'))
diff --git a/tests/extmod/uctypes_32bit_intbig.py b/tests/extmod/uctypes_32bit_intbig.py
index a082dc3704..6b4d3d76cd 100644
--- a/tests/extmod/uctypes_32bit_intbig.py
+++ b/tests/extmod/uctypes_32bit_intbig.py
@@ -3,9 +3,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 buf = b"12345678abcd"
 struct = uctypes.struct(
diff --git a/tests/extmod/uctypes_array_assign_le.py b/tests/extmod/uctypes_array_assign_le.py
index bae467d092..6afa7e0a24 100644
--- a/tests/extmod/uctypes_array_assign_le.py
+++ b/tests/extmod/uctypes_array_assign_le.py
@@ -1,9 +1,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     # arr is array at offset 0, of UINT8 elements, array size is 2
diff --git a/tests/extmod/uctypes_array_assign_native_le.py b/tests/extmod/uctypes_array_assign_native_le.py
index f0ecc0dad4..a538bf9add 100644
--- a/tests/extmod/uctypes_array_assign_native_le.py
+++ b/tests/extmod/uctypes_array_assign_native_le.py
@@ -3,11 +3,11 @@ try:
     import uctypes
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 if sys.byteorder != "little":
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     # arr is array at offset 0, of UINT8 elements, array size is 2
diff --git a/tests/extmod/uctypes_array_assign_native_le_intbig.py b/tests/extmod/uctypes_array_assign_native_le_intbig.py
index f29a3b66e9..84dfba0e29 100644
--- a/tests/extmod/uctypes_array_assign_native_le_intbig.py
+++ b/tests/extmod/uctypes_array_assign_native_le_intbig.py
@@ -3,11 +3,11 @@ try:
     import uctypes
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 if sys.byteorder != "little":
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     # arr is array at offset 0, of UINT8 elements, array size is 2
diff --git a/tests/extmod/uctypes_bytearray.py b/tests/extmod/uctypes_bytearray.py
index bf7845ab26..61c7da271f 100644
--- a/tests/extmod/uctypes_bytearray.py
+++ b/tests/extmod/uctypes_bytearray.py
@@ -1,9 +1,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     "arr": (uctypes.ARRAY | 0, uctypes.UINT8 | 2),
diff --git a/tests/extmod/uctypes_le.py b/tests/extmod/uctypes_le.py
index 829beda58b..7df5ac0909 100644
--- a/tests/extmod/uctypes_le.py
+++ b/tests/extmod/uctypes_le.py
@@ -1,9 +1,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     "s0": uctypes.UINT16 | 0,
diff --git a/tests/extmod/uctypes_le_float.py b/tests/extmod/uctypes_le_float.py
index a61305ba86..84ff2b84cf 100644
--- a/tests/extmod/uctypes_le_float.py
+++ b/tests/extmod/uctypes_le_float.py
@@ -1,9 +1,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     "f32": uctypes.FLOAT32 | 0,
diff --git a/tests/extmod/uctypes_native_float.py b/tests/extmod/uctypes_native_float.py
index 80cb54383d..acef47036d 100644
--- a/tests/extmod/uctypes_native_float.py
+++ b/tests/extmod/uctypes_native_float.py
@@ -1,9 +1,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     "f32": uctypes.FLOAT32 | 0,
diff --git a/tests/extmod/uctypes_native_le.py b/tests/extmod/uctypes_native_le.py
index 5900224d41..8bba03b38c 100644
--- a/tests/extmod/uctypes_native_le.py
+++ b/tests/extmod/uctypes_native_le.py
@@ -6,11 +6,11 @@ try:
     import uctypes
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 if sys.byteorder != "little":
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 desc = {
diff --git a/tests/extmod/uctypes_print.py b/tests/extmod/uctypes_print.py
index 76a009dc75..c310238e54 100644
--- a/tests/extmod/uctypes_print.py
+++ b/tests/extmod/uctypes_print.py
@@ -2,9 +2,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # we use an address of "0" because we just want to print something deterministic
 # and don't actually need to set/get any values in the struct
diff --git a/tests/extmod/uctypes_ptr_le.py b/tests/extmod/uctypes_ptr_le.py
index e8a6243ce1..056e456506 100644
--- a/tests/extmod/uctypes_ptr_le.py
+++ b/tests/extmod/uctypes_ptr_le.py
@@ -3,11 +3,11 @@ try:
     import uctypes
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 if sys.byteorder != "little":
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     "ptr": (uctypes.PTR | 0, uctypes.UINT8),
diff --git a/tests/extmod/uctypes_ptr_native_le.py b/tests/extmod/uctypes_ptr_native_le.py
index 9b016c04d5..24508b1cb4 100644
--- a/tests/extmod/uctypes_ptr_native_le.py
+++ b/tests/extmod/uctypes_ptr_native_le.py
@@ -3,11 +3,11 @@ try:
     import uctypes
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 if sys.byteorder != "little":
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 desc = {
diff --git a/tests/extmod/uctypes_sizeof.py b/tests/extmod/uctypes_sizeof.py
index 266cd06943..5a6adb4376 100644
--- a/tests/extmod/uctypes_sizeof.py
+++ b/tests/extmod/uctypes_sizeof.py
@@ -1,9 +1,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     # arr is array at offset 0, of UINT8 elements, array size is 2
diff --git a/tests/extmod/uctypes_sizeof_native.py b/tests/extmod/uctypes_sizeof_native.py
index f676c8c6de..32c740e773 100644
--- a/tests/extmod/uctypes_sizeof_native.py
+++ b/tests/extmod/uctypes_sizeof_native.py
@@ -1,9 +1,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 S1 = {}
 assert uctypes.sizeof(S1) == 0
diff --git a/tests/extmod/uhashlib_sha1.py b/tests/extmod/uhashlib_sha1.py
index f12fc649aa..4f7066899a 100644
--- a/tests/extmod/uhashlib_sha1.py
+++ b/tests/extmod/uhashlib_sha1.py
@@ -1,4 +1,3 @@
-import sys
 try:
     import uhashlib as hashlib
 except ImportError:
@@ -8,14 +7,14 @@ except ImportError:
         # This is neither uPy, nor cPy, so must be uPy with
         # uhashlib module disabled.
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 try:
     hashlib.sha1
 except AttributeError:
     # SHA1 is only available on some ports
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 sha1 = hashlib.sha1(b'hello')
 sha1.update(b'world')
diff --git a/tests/extmod/uhashlib_sha256.py b/tests/extmod/uhashlib_sha256.py
index ff51f2ffa5..3200e8f5cd 100644
--- a/tests/extmod/uhashlib_sha256.py
+++ b/tests/extmod/uhashlib_sha256.py
@@ -1,4 +1,3 @@
-import sys
 try:
     import uhashlib as hashlib
 except ImportError:
@@ -8,7 +7,7 @@ except ImportError:
         # This is neither uPy, nor cPy, so must be uPy with
         # uhashlib module disabled.
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 
 h = hashlib.sha256()
diff --git a/tests/extmod/uheapq1.py b/tests/extmod/uheapq1.py
index 4b0e5de57e..7c1fe4e1ec 100644
--- a/tests/extmod/uheapq1.py
+++ b/tests/extmod/uheapq1.py
@@ -4,9 +4,8 @@ except:
     try:
         import heapq
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 try:
     heapq.heappop([])
diff --git a/tests/extmod/ujson_dumps.py b/tests/extmod/ujson_dumps.py
index 4a02f51704..d732718019 100644
--- a/tests/extmod/ujson_dumps.py
+++ b/tests/extmod/ujson_dumps.py
@@ -4,9 +4,8 @@ except ImportError:
     try:
         import json
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 print(json.dumps(False))
 print(json.dumps(True))
diff --git a/tests/extmod/ujson_dumps_extra.py b/tests/extmod/ujson_dumps_extra.py
index a52e8224c4..21a388c32d 100644
--- a/tests/extmod/ujson_dumps_extra.py
+++ b/tests/extmod/ujson_dumps_extra.py
@@ -3,8 +3,7 @@
 try:
     import ujson
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(ujson.dumps(b'1234'))
diff --git a/tests/extmod/ujson_dumps_float.py b/tests/extmod/ujson_dumps_float.py
index d949ea6ddd..e8cceb6f1a 100644
--- a/tests/extmod/ujson_dumps_float.py
+++ b/tests/extmod/ujson_dumps_float.py
@@ -4,8 +4,7 @@ except ImportError:
     try:
         import json
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 print(json.dumps(1.2))
diff --git a/tests/extmod/ujson_load.py b/tests/extmod/ujson_load.py
index 901132a5f8..9725ab2ddc 100644
--- a/tests/extmod/ujson_load.py
+++ b/tests/extmod/ujson_load.py
@@ -6,9 +6,8 @@ except:
         from io import StringIO
         import json
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 print(json.load(StringIO('null')))
 print(json.load(StringIO('"abc\\u0064e"')))
diff --git a/tests/extmod/ujson_loads.py b/tests/extmod/ujson_loads.py
index b2e18e3af7..adba3c068d 100644
--- a/tests/extmod/ujson_loads.py
+++ b/tests/extmod/ujson_loads.py
@@ -4,9 +4,8 @@ except ImportError:
     try:
         import json
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 def my_print(o):
     if isinstance(o, dict):
diff --git a/tests/extmod/ujson_loads_float.py b/tests/extmod/ujson_loads_float.py
index b20a412ffb..f1b8cc364c 100644
--- a/tests/extmod/ujson_loads_float.py
+++ b/tests/extmod/ujson_loads_float.py
@@ -4,9 +4,8 @@ except ImportError:
     try:
         import json
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 def my_print(o):
     print('%.3f' % o)
diff --git a/tests/extmod/urandom_basic.py b/tests/extmod/urandom_basic.py
index 885b8517f4..57e6b26cba 100644
--- a/tests/extmod/urandom_basic.py
+++ b/tests/extmod/urandom_basic.py
@@ -4,9 +4,8 @@ except ImportError:
     try:
         import random
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 # check getrandbits returns a value within the bit range
 for b in (1, 2, 3, 4, 16, 32):
diff --git a/tests/extmod/urandom_extra.py b/tests/extmod/urandom_extra.py
index 925dd0dbcb..f5a34e1687 100644
--- a/tests/extmod/urandom_extra.py
+++ b/tests/extmod/urandom_extra.py
@@ -4,16 +4,14 @@ except ImportError:
     try:
         import random
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 try:
     random.randint
 except AttributeError:
-    import sys
     print('SKIP')
-    sys.exit()
+    raise SystemExit
 
 print('randrange')
 for i in range(50):
diff --git a/tests/extmod/ure1.py b/tests/extmod/ure1.py
index a867f17515..1f38b80876 100644
--- a/tests/extmod/ure1.py
+++ b/tests/extmod/ure1.py
@@ -4,9 +4,8 @@ except ImportError:
     try:
         import re
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 r = re.compile(".+")
 m = r.match("abc")
diff --git a/tests/extmod/ure_debug.py b/tests/extmod/ure_debug.py
index 252df21e30..cfb264bb6d 100644
--- a/tests/extmod/ure_debug.py
+++ b/tests/extmod/ure_debug.py
@@ -2,8 +2,7 @@
 try:
     import ure
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 ure.compile('^a|b[0-9]\w$', ure.DEBUG)
diff --git a/tests/extmod/ure_error.py b/tests/extmod/ure_error.py
index 3f16f9158c..f52f735c7f 100644
--- a/tests/extmod/ure_error.py
+++ b/tests/extmod/ure_error.py
@@ -6,9 +6,8 @@ except ImportError:
     try:
         import re
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 def test_re(r):
     try:
diff --git a/tests/extmod/ure_group.py b/tests/extmod/ure_group.py
index 98aae2a736..4e39468c5b 100644
--- a/tests/extmod/ure_group.py
+++ b/tests/extmod/ure_group.py
@@ -6,9 +6,8 @@ except ImportError:
     try:
         import re
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 def print_groups(match):
     print('----')
diff --git a/tests/extmod/ure_namedclass.py b/tests/extmod/ure_namedclass.py
index e233f17c88..215d09613f 100644
--- a/tests/extmod/ure_namedclass.py
+++ b/tests/extmod/ure_namedclass.py
@@ -6,9 +6,8 @@ except ImportError:
     try:
         import re
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 def print_groups(match):
     print('----')
diff --git a/tests/extmod/ure_split.py b/tests/extmod/ure_split.py
index 1e411c27c5..317ca98927 100644
--- a/tests/extmod/ure_split.py
+++ b/tests/extmod/ure_split.py
@@ -4,9 +4,8 @@ except ImportError:
     try:
         import re
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 r = re.compile(" ")
 s = r.split("a b c foobar")
diff --git a/tests/extmod/ure_split_empty.py b/tests/extmod/ure_split_empty.py
index ad6334ebae..76ce97ea67 100644
--- a/tests/extmod/ure_split_empty.py
+++ b/tests/extmod/ure_split_empty.py
@@ -7,9 +7,8 @@
 try:
     import ure as re
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 r = re.compile(" *")
 s = r.split("a b    c   foobar")
diff --git a/tests/extmod/ure_split_notimpl.py b/tests/extmod/ure_split_notimpl.py
index eca3ea512e..da6e9652d0 100644
--- a/tests/extmod/ure_split_notimpl.py
+++ b/tests/extmod/ure_split_notimpl.py
@@ -1,9 +1,8 @@
 try:
     import ure as re
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 r = re.compile('( )')
 try:
diff --git a/tests/extmod/ussl_basic.py b/tests/extmod/ussl_basic.py
index e9d435bca8..9f8019a0bc 100644
--- a/tests/extmod/ussl_basic.py
+++ b/tests/extmod/ussl_basic.py
@@ -5,8 +5,7 @@ try:
     import ussl as ssl
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 # create in client mode
 try:
diff --git a/tests/extmod/utimeq1.py b/tests/extmod/utimeq1.py
index 68d69e25e6..dc7f3b6600 100644
--- a/tests/extmod/utimeq1.py
+++ b/tests/extmod/utimeq1.py
@@ -5,8 +5,7 @@ try:
     from utimeq import utimeq
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 DEBUG = 0
 
diff --git a/tests/extmod/utimeq_stable.py b/tests/extmod/utimeq_stable.py
index 9f6ba76d4a..9fb522d514 100644
--- a/tests/extmod/utimeq_stable.py
+++ b/tests/extmod/utimeq_stable.py
@@ -2,8 +2,7 @@ try:
     from utimeq import utimeq
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 h = utimeq(10)
 
diff --git a/tests/extmod/uzlib_decompio.py b/tests/extmod/uzlib_decompio.py
index 6f07c048c7..112a825976 100644
--- a/tests/extmod/uzlib_decompio.py
+++ b/tests/extmod/uzlib_decompio.py
@@ -2,9 +2,8 @@ try:
     import uzlib as zlib
     import uio as io
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 # Raw DEFLATE bitstream
diff --git a/tests/extmod/uzlib_decompio_gz.py b/tests/extmod/uzlib_decompio_gz.py
index 7572e96939..02087f7639 100644
--- a/tests/extmod/uzlib_decompio_gz.py
+++ b/tests/extmod/uzlib_decompio_gz.py
@@ -2,9 +2,8 @@ try:
     import uzlib as zlib
     import uio as io
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 # gzip bitstream
diff --git a/tests/extmod/uzlib_decompress.py b/tests/extmod/uzlib_decompress.py
index 10121ee7e1..63247955c9 100644
--- a/tests/extmod/uzlib_decompress.py
+++ b/tests/extmod/uzlib_decompress.py
@@ -4,9 +4,8 @@ except ImportError:
     try:
         import uzlib as zlib
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 PATTERNS = [
     # Packed results produced by CPy's zlib.compress()
diff --git a/tests/extmod/vfs_basic.py b/tests/extmod/vfs_basic.py
index a3b2f3c29b..4fc67d34b2 100644
--- a/tests/extmod/vfs_basic.py
+++ b/tests/extmod/vfs_basic.py
@@ -9,8 +9,7 @@ try:
     uos.mount
 except (ImportError, AttributeError):
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 
 class Filesystem:
@@ -57,6 +56,9 @@ for path in uos.listdir('/'):
 # stat root dir
 print(uos.stat('/'))
 
+# statvfs root dir; verify that f_namemax has a sensible size
+print(uos.statvfs('/')[9] >= 32)
+
 # getcwd when in root dir
 print(uos.getcwd())
 
@@ -128,6 +130,8 @@ except OSError:
 
 # root dir
 uos.mount(Filesystem(3), '/')
+print(uos.stat('/'))
+print(uos.statvfs('/'))
 print(uos.listdir())
 open('test')
 
diff --git a/tests/extmod/vfs_basic.py.exp b/tests/extmod/vfs_basic.py.exp
index 8a23aa8ae7..0ae2c2cc97 100644
--- a/tests/extmod/vfs_basic.py.exp
+++ b/tests/extmod/vfs_basic.py.exp
@@ -1,4 +1,5 @@
 (16384, 0, 0, 0, 0, 0, 0, 0, 0, 0)
+True
 /
 1 mount False False
 ['test_mnt']
@@ -36,6 +37,9 @@ OSError
 2 umount
 OSError
 3 mount False False
+(16384, 0, 0, 0, 0, 0, 0, 0, 0, 0)
+3 statvfs /
+(3,)
 3 ilistdir /
 ['a3']
 3 open test r
diff --git a/tests/extmod/vfs_fat_fileio1.py b/tests/extmod/vfs_fat_fileio1.py
index 9036df7a5c..d19df120b5 100644
--- a/tests/extmod/vfs_fat_fileio1.py
+++ b/tests/extmod/vfs_fat_fileio1.py
@@ -1,4 +1,3 @@
-import sys
 try:
     import uerrno
     try:
@@ -8,13 +7,13 @@ try:
         import uos
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 try:
     uos.VfsFat
 except AttributeError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 class RAMFS:
@@ -46,7 +45,7 @@ try:
     bdev = RAMFS(50)
 except MemoryError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 uos.VfsFat.mkfs(bdev)
 vfs = uos.VfsFat(bdev)
diff --git a/tests/extmod/vfs_fat_fileio2.py b/tests/extmod/vfs_fat_fileio2.py
index b2a0ba70f4..b5adb75c96 100644
--- a/tests/extmod/vfs_fat_fileio2.py
+++ b/tests/extmod/vfs_fat_fileio2.py
@@ -1,4 +1,3 @@
-import sys
 try:
     import uerrno
     try:
@@ -8,13 +7,13 @@ try:
         import uos
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 try:
     uos.VfsFat
 except AttributeError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 class RAMFS:
@@ -46,7 +45,7 @@ try:
     bdev = RAMFS(50)
 except MemoryError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 uos.VfsFat.mkfs(bdev)
 vfs = uos.VfsFat(bdev)
diff --git a/tests/extmod/vfs_fat_more.py b/tests/extmod/vfs_fat_more.py
index dacb215535..baec96787b 100644
--- a/tests/extmod/vfs_fat_more.py
+++ b/tests/extmod/vfs_fat_more.py
@@ -1,4 +1,3 @@
-import sys
 import uerrno
 try:
     try:
@@ -8,13 +7,13 @@ try:
         import uos
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 try:
     uos.VfsFat
 except AttributeError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 class RAMFS:
@@ -47,7 +46,7 @@ try:
     bdev2 = RAMFS(50)
 except MemoryError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # first we umount any existing mount points the target may have
 try:
diff --git a/tests/extmod/vfs_fat_oldproto.py b/tests/extmod/vfs_fat_oldproto.py
index 3e66758c36..ef4f1da78e 100644
--- a/tests/extmod/vfs_fat_oldproto.py
+++ b/tests/extmod/vfs_fat_oldproto.py
@@ -1,4 +1,3 @@
-import sys
 try:
     import uerrno
     try:
@@ -7,13 +6,13 @@ try:
         import uos
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 try:
     uos.VfsFat
 except AttributeError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 class RAMFS_OLD:
 
@@ -43,7 +42,7 @@ try:
     bdev = RAMFS_OLD(50)
 except MemoryError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 uos.VfsFat.mkfs(bdev)
 vfs = uos.VfsFat(bdev)
diff --git a/tests/extmod/vfs_fat_ramdisk.py b/tests/extmod/vfs_fat_ramdisk.py
index fe72a8beff..801c697862 100644
--- a/tests/extmod/vfs_fat_ramdisk.py
+++ b/tests/extmod/vfs_fat_ramdisk.py
@@ -1,4 +1,3 @@
-import sys
 try:
     import uerrno
     try:
@@ -7,13 +6,13 @@ try:
         import uos
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 try:
     uos.VfsFat
 except AttributeError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 class RAMFS:
@@ -45,7 +44,7 @@ try:
     bdev = RAMFS(50)
 except MemoryError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 uos.VfsFat.mkfs(bdev)
 
diff --git a/tests/extmod/websocket_basic.py b/tests/extmod/websocket_basic.py
index 770836c8eb..9a80503a03 100644
--- a/tests/extmod/websocket_basic.py
+++ b/tests/extmod/websocket_basic.py
@@ -3,9 +3,8 @@ try:
     import uerrno
     import websocket
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # put raw data in the stream and do a websocket read
 def ws_read(msg, sz):