modmachine: Implement physical memory access using /dev/mem (Linux, etc).

This requires root access. And on recent Linux kernels, with
CONFIG_STRICT_DEVMEM option enabled, only address ranges listed in
/proc/iomem can be accessed. The above compiled-time option can be
however overriden with boot-time option "iomem=relaxed".

This also removed separate read/write paths - there unlikely would
be a case when they're different.

1 files changed, 16 insertions, 0 deletions

diff --git a/tests/extmod/machine_mem.py b/tests/extmod/machine_mem.py
new file mode 100644
index 000000000..7d8a9ac01
--- /dev/null
+++ b/tests/extmod/machine_mem.py
@@ -0,0 +1,16 @@
+# This test requires root privilege, so is usually skipped
+# It also assumes x86 legacy hardware (with Video BIOS present).
+
+try:
+    import machine
+except ImportError:
+    print("SKIP")
+    import sys
+    sys.exit()
+
+try:
+    print(hex(machine.mem16[0xc0000]))
+except OSError:
+    print("SKIP")
+    import sys
+    sys.exit()