partition_table: warn if data partition offset is not 4kB aligned

If a partition offset is not aligned to 4 kB, erase operations will
fail, even if they are aligned to 4 kB relative to the partition
start. This is because the underlying esp_flash_erase_range function
only works when the address is aligned to 4 kB.

Not making this an error for now, since applications might be using
read-only non-4kB aligned partitions, which still work fine.
Will change this behavior in IDF 5.0, requiring 4 kB alignment for all
partitions.

Closes https://github.com/espressif/esp-idf/issues/7295
Closes https://github.com/espressif/esp-idf/issues/7350

components/partition_table/gen_esp32part.py

@@ -92,6 +92,19 @@ def get_subtype_as_int(ptype, subtype):
             return subtype
 
 
+ALIGNMENT = {
+    APP_TYPE: 0x10000,
+    DATA_TYPE: 0x4,
+}
+
+
+STRICT_DATA_ALIGNMENT = 0x1000
+
+
+def get_alignment_for_type(ptype):
+    return ALIGNMENT.get(ptype, ALIGNMENT[DATA_TYPE])
+
+
 quiet = False
 md5sum = True
 secure = False
@@ -161,7 +174,7 @@ class PartitionTable(list):
                     raise InputError('CSV Error: Partitions overlap. Partition at line %d sets offset 0x%x. Previous partition ends 0x%x'
                                      % (e.line_no, e.offset, last_end))
             if e.offset is None:
-                pad_to = 0x10000 if e.type == APP_TYPE else 4
+                pad_to = get_alignment_for_type(e.type)
                 if last_end % pad_to != 0:
                     last_end += pad_to - (last_end % pad_to)
                 e.offset = last_end
@@ -287,11 +300,6 @@ class PartitionTable(list):
 class PartitionDefinition(object):
     MAGIC_BYTES = b'\xAA\x50'
 
-    ALIGNMENT = {
-        APP_TYPE: 0x10000,
-        DATA_TYPE: 0x04,
-    }
-
     # dictionary maps flag name (as used in CSV flags list, property name)
     # to bit set in flags words in binary format
     FLAGS = {
@@ -388,9 +396,14 @@ class PartitionDefinition(object):
             raise ValidationError(self, 'Subtype field is not set')
         if self.offset is None:
             raise ValidationError(self, 'Offset field is not set')
-        align = self.ALIGNMENT.get(self.type, 4)
+        align = get_alignment_for_type(self.type)
         if self.offset % align:
             raise ValidationError(self, 'Offset 0x%x is not aligned to 0x%x' % (self.offset, align))
+        # The alignment requirement for non-app partition is 4 bytes, but it should be 4 kB.
+        # Print a warning for now, make it an error in IDF 5.0 (IDF-3742).
+        if self.type != APP_TYPE and self.offset % STRICT_DATA_ALIGNMENT:
+            critical('WARNING: Partition %s not aligned to 0x%x.'
+                     'This is deprecated and will be considered an error in the future release.' % (self.name, STRICT_DATA_ALIGNMENT))
         if self.size % align and secure and self.type == APP_TYPE:
             raise ValidationError(self, 'Size 0x%x is not aligned to 0x%x' % (self.size, align))
         if self.size is None:

components/partition_table/test_gen_esp32part_host/gen_esp32part_tests.py

@@ -451,6 +451,19 @@ ota_1,             0,  ota_1,          , 1M,
             self.assertIn('WARNING', sys.stderr.getvalue())
             self.assertIn('partition subtype', sys.stderr.getvalue())
 
+            sys.stderr = io.StringIO()
+            csv_3 = 'nvs, data, nvs, 0x8800, 32k'
+            gen_esp32part.PartitionTable.from_csv(csv_3).verify()
+            self.assertIn('WARNING', sys.stderr.getvalue())
+            self.assertIn('not aligned to 0x1000', sys.stderr.getvalue())
+
+            sys.stderr = io.StringIO()
+            csv_4 = 'factory, app, factory, 0x10000, 0x100100\n' \
+                    'nvs, data, nvs, , 32k'
+            gen_esp32part.PartitionTable.from_csv(csv_4).verify()
+            self.assertIn('WARNING', sys.stderr.getvalue())
+            self.assertIn('not aligned to 0x1000', sys.stderr.getvalue())
+
         finally:
             sys.stderr = sys.__stderr__