pmb.parse.bootimg: detect mediatek header (MR 1955)

Some Mediatek devices have a special 512-byte header around the zImage
which must be generated so the device boots.

Support for that exists for a while in postmarketOS but detection was
missing. Add that.

pmb/aportgen/device.py

@@ -107,6 +107,7 @@ def generate_deviceinfo_fastboot_content(args, bootimg=None):
     if bootimg is None:
         bootimg = {"cmdline": "",
                    "qcdt": "false",
+                   "mtk_mkimage": "false",
                    "dtb_second": "false",
                    "base": "",
                    "kernel_offset": "",
@@ -118,6 +119,7 @@ def generate_deviceinfo_fastboot_content(args, bootimg=None):
         deviceinfo_kernel_cmdline="{bootimg["cmdline"]}"
         deviceinfo_generate_bootimg="true"
         deviceinfo_bootimg_qcdt="{bootimg["qcdt"]}"
+        deviceinfo_bootimg_mtk_mkimage="{bootimg["mtk_mkimage"]}"
         deviceinfo_bootimg_dtb_second="{bootimg["dtb_second"]}"
         deviceinfo_flash_offset_base="{bootimg["base"]}"
         deviceinfo_flash_offset_kernel="{bootimg["kernel_offset"]}"

pmb/chroot/other.py

@@ -28,7 +28,7 @@ def kernel_flavors_installed(args, suffix, autoinstall=True):
     ret = []
     for file in glob.glob(pattern):
         flavor = os.path.basename(file)[prefix_len:]
-        if flavor[-4:] == "-dtb":
+        if flavor[-4:] == "-dtb" or flavor[-4:] == "-mtk":
             flavor = flavor[:-4]
         ret.append(flavor)
 

pmb/config/__init__.py

@@ -342,6 +342,7 @@ deviceinfo_attributes = [
     "kernel_cmdline",
     "generate_bootimg",
     "bootimg_qcdt",
+    "bootimg_mtk_mkimage",
     "bootimg_dtb_second",
     "flash_offset_base",
     "flash_offset_kernel",

pmb/parse/bootimg.py

@@ -13,6 +13,25 @@ def is_dtb(path):
         return f.read(4) == b'\xd0\x0d\xfe\xed'
 
 
+def has_mtk_header(path, supported_label):
+    with open(path, 'rb') as f:
+        # Check Mediatek header (0x88168858)
+        if not f.read(4) == b'\x88\x16\x88\x58':
+            return False
+        f.seek(8)
+        label = f.read(32).decode("utf-8").rstrip('\0')
+        # We only support hardcoded labels for now as the known devices only
+        # use KERNEL & ROOTFS for kernel and ramdisk respectively. To change
+        # this, deviceinfo would need to store the label and
+        # postmarketos-mkinitfs would need to use that label.
+        if label != supported_label:
+            raise RuntimeError(f"Only '{supported_label}' is supported as label,"
+                               f" but your device has '{label}'. Please create"
+                               f" an issue and attach your boot.img:"
+                               f" https://postmarketos.org/issues")
+        return True
+
+
 def bootimg(args, path):
     if not os.path.exists(path):
         raise RuntimeError("Could not find file '" + path + "'")
@@ -70,8 +89,13 @@ 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["mtk_mkimage"] = ("true" if has_mtk_header(bootimg_path + "-zImage", "KERNEL") else "false")
     output["dtb_second"] = ("true" if is_dtb(bootimg_path + "-second") else "false")
 
+    # Mediatek: Check that the ramdisk also has a known-good label
+    # We don't care about the return value, just whether it throws an exception or not.
+    has_mtk_header(bootimg_path + "-ramdisk.gz", "ROOTFS")
+
     # Cleanup
     pmb.chroot.root(args, ["rm", "-r", temp_path])
 

test/test_bootimg.py

@@ -51,6 +51,7 @@ def test_bootimg_normal(args):
               "pagesize": "2048",
               "cmdline": "bootopt=64S3,32S1,32S1",
               "qcdt": "false",
+              "mtk_mkimage": "false",
               "dtb_second": "false"}
     assert pmb.parse.bootimg(args, path) == output
 
@@ -65,6 +66,22 @@ def test_bootimg_qcdt(args):
               "pagesize": "2048",
               "cmdline": "bootopt=64S3,32S1,32S1",
               "qcdt": "true",
+              "mtk_mkimage": "false",
+              "dtb_second": "false"}
+    assert pmb.parse.bootimg(args, path) == output
+
+
+def test_bootimg_mtk_mkimage(args):
+    path = pmb_test.const.testdata + "/bootimg/mtk_mkimage-boot.img"
+    output = {"base": "0x80000000",
+              "kernel_offset": "0x00008000",
+              "ramdisk_offset": "0x04000000",
+              "second_offset": "0x00f00000",
+              "tags_offset": "0x0e000000",
+              "pagesize": "2048",
+              "cmdline": "bootopt=64S3,32S1,32S1",
+              "qcdt": "false",
+              "mtk_mkimage": "true",
               "dtb_second": "false"}
     assert pmb.parse.bootimg(args, path) == output
 
@@ -79,5 +96,6 @@ def test_bootimg_dtb_second(args):
               "pagesize": "2048",
               "cmdline": "bootopt=64S3,32S1,32S1",
               "qcdt": "false",
+              "mtk_mkimage": "false",
               "dtb_second": "true"}
     assert pmb.parse.bootimg(args, path) == output

test/test_questions.py

@@ -98,6 +98,7 @@ def test_questions_bootimg(args, monkeypatch):
               "pagesize": "2048",
               "cmdline": "bootopt=64S3,32S1,32S1",
               "qcdt": "false",
+              "mtk_mkimage": "false",
               "dtb_second": "false"}
     assert func(args) == output