Detect if DTB is placed in second area of Android boot image (!1828)

postmarketOS/pmaports!700 adds a new "deviceinfo_bootimg_dtb_second"
option that places the DTB in the "second" area of the Android boot
image.

Attempt to detect this automatically by checking the extracted
second binary for the FDT magic (0xd00dfeed).

pmb/aportgen/device.py

@@ -106,6 +106,7 @@ def generate_deviceinfo_fastboot_content(args, bootimg=None):
     if bootimg is None:
         bootimg = {"cmdline": "",
                    "qcdt": "false",
+                   "dtb_second": "false",
                    "base": "",
                    "kernel_offset": "",
                    "ramdisk_offset": "",
@@ -116,6 +117,7 @@ def generate_deviceinfo_fastboot_content(args, bootimg=None):
         deviceinfo_kernel_cmdline=\"""" + bootimg["cmdline"] + """\"
         deviceinfo_generate_bootimg="true"
         deviceinfo_bootimg_qcdt=\"""" + bootimg["qcdt"] + """\"
+        deviceinfo_bootimg_dtb_second=\"""" + bootimg["dtb_second"] + """\"
         deviceinfo_flash_offset_base=\"""" + bootimg["base"] + """\"
         deviceinfo_flash_offset_kernel=\"""" + bootimg["kernel_offset"] + """\"
         deviceinfo_flash_offset_ramdisk=\"""" + bootimg["ramdisk_offset"] + """\"

pmb/config/__init__.py

@@ -267,6 +267,7 @@ deviceinfo_attributes = [
     "kernel_cmdline",
     "generate_bootimg",
     "bootimg_qcdt",
+    "bootimg_dtb_second",
     "flash_offset_base",
     "flash_offset_kernel",
     "flash_offset_ramdisk",

pmb/parse/bootimg.py

@@ -21,6 +21,14 @@ import logging
 import pmb
 
 
+def is_dtb(path):
+    if not os.path.isfile(path):
+        return False
+    with open(path, 'rb') as f:
+        # Check FDT magic identifier (0xd00dfeed)
+        return f.read(4) == b'\xd0\x0d\xfe\xed'
+
+
 def bootimg(args, path):
     if not os.path.exists(path):
         raise RuntimeError("Could not find file '" + path + "'")
@@ -77,6 +85,7 @@ def bootimg(args, path):
         output["cmdline"] = f.read().replace('\n', '')
     output["qcdt"] = ("true" if os.path.isfile(bootimg_path + "-dt") and
                       os.path.getsize(bootimg_path + "-dt") > 0 else "false")
+    output["dtb_second"] = ("true" if is_dtb(bootimg_path + "-second") else "false")
 
     # Cleanup
     pmb.chroot.root(args, ["rm", "-r", temp_path])

test/test_bootimg.py

@@ -68,7 +68,8 @@ def test_bootimg_normal(args):
               "tags_offset": "0x0e000000",
               "pagesize": "2048",
               "cmdline": "bootopt=64S3,32S1,32S1",
-              "qcdt": "false"}
+              "qcdt": "false",
+              "dtb_second": "false"}
     assert pmb.parse.bootimg(args, path) == output
 
 
@@ -81,5 +82,20 @@ def test_bootimg_qcdt(args):
               "tags_offset": "0x0e000000",
               "pagesize": "2048",
               "cmdline": "bootopt=64S3,32S1,32S1",
-              "qcdt": "true"}
+              "qcdt": "true",
+              "dtb_second": "false"}
+    assert pmb.parse.bootimg(args, path) == output
+
+
+def test_bootimg_dtb_second(args):
+    path = pmb_src + "/test/testdata/bootimg/dtb-second-boot.img"
+    output = {"base": "0x00000000",
+              "kernel_offset": "0x00008000",
+              "ramdisk_offset": "0x02000000",
+              "second_offset": "0x00f00000",
+              "tags_offset": "0x00000100",
+              "pagesize": "2048",
+              "cmdline": "bootopt=64S3,32S1,32S1",
+              "qcdt": "false",
+              "dtb_second": "true"}
     assert pmb.parse.bootimg(args, path) == output

test/test_questions.py

@@ -113,7 +113,8 @@ def test_questions_bootimg(args, monkeypatch):
               "tags_offset": "0x0e000000",
               "pagesize": "2048",
               "cmdline": "bootopt=64S3,32S1,32S1",
-              "qcdt": "false"}
+              "qcdt": "false",
+              "dtb_second": "false"}
     assert func(args) == output