esp8266/boards: Add FLASH_2M_ROMFS variant with 320k ROM partition.

The same as the 2M flash variant but with a 320KiB ROM partition.

Signed-off-by: Damien George <damien@micropython.org>

ports/esp8266/boards/ESP8266_GENERIC/board.json

@@ -17,7 +17,8 @@
     "variants": {
         "OTA": "OTA compatible",
         "FLASH_1M": "1MiB flash",
-        "FLASH_512K": "512kiB flash"
+        "FLASH_512K": "512kiB flash",
+        "FLASH_2M_ROMFS": "2MiB flash with ROMFS"
     },
     "vendor": "Espressif"
 }

ports/esp8266/boards/ESP8266_GENERIC/mpconfigvariant_FLASH_2M_ROMFS.mk

@@ -0,0 +1,12 @@
+LD_FILES = boards/esp8266_2MiB_ROMFS.ld
+
+MICROPY_PY_ESPNOW ?= 1
+MICROPY_PY_BTREE ?= 1
+MICROPY_VFS_FAT ?= 1
+MICROPY_VFS_LFS2 ?= 1
+
+# Add asyncio and extra micropython-lib packages (in addition to the port manifest).
+FROZEN_MANIFEST ?= $(BOARD_DIR)/manifest_2MiB.py
+
+# Configure mpconfigboard.h.
+CFLAGS += -DMICROPY_ESP8266_2M -DMICROPY_VFS_ROM=1

ports/esp8266/boards/esp8266_2MiB_ROMFS.ld

@@ -0,0 +1,24 @@
+/* GNU linker script for ESP8266 with 2M or more flash, and includes a ROMFS partition
+
+   Flash layout:
+    0x40200000 36k  header + iram/dram init
+    0x40209000 668k firmware (irom0)
+    0x402c0000 320k ROMFS
+    0x40300000 1M+  filesystem (not memory mapped)
+*/
+
+MEMORY
+{
+    dport0_0_seg : org = 0x3ff00000, len = 16
+    dram0_0_seg :  org = 0x3ffe8000, len = 80K
+    iram1_0_seg :  org = 0x40100000, len = 32K
+    irom0_0_seg :  org = 0x40209000, len = 1M - 36K - 320K
+    FLASH_ROMFS :  org = 0x402b0000, len = 320K
+}
+
+/* define ROMFS extents */
+_micropy_hw_romfs_start = ORIGIN(FLASH_ROMFS);
+_micropy_hw_romfs_size = LENGTH(FLASH_ROMFS);
+
+/* define common sections and symbols */
+INCLUDE boards/esp8266_common.ld