Firefox OS/Performance/Modifying boot.img: Difference between revisions

Firefox OS/Performance/Modifying boot.img (view source)

128 bytes added , 24 June 2014

Confirmed users

125

edits

@@ Line 20: / Line 20: @@
 ===Splitting the boot.img===
-<br>
+This partition contains 2-3 distinct entities. The kernel, the ramdisk, and (optionally, based on how the kernel was configured) the device tree binary. The instructions outlined [https://developer.mozilla.org/en-US/Firefox_OS/Porting#Rebuild_boot.img here] for splitting a boot.img are only mostly sufficient on a flame. The tool specified only detects the kernel and ramdisk. For more information on the structure of this partition go here: https://github.com/xiaolu/mkbootimg_tools/blob/master/dtbtool.txt .
-This partition contains 2-3 distinct entities. The kernel, the ramdisk, and (optionally, based on how the kernel was configured) the device tree binary. The instructions outlined [https://developer.mozilla.org/en-US/Firefox_OS/Porting#Rebuild_boot.img here] for splitting a boot.img are only mostly sufficient on a flame. The tool specified only detects the kernel and ramdisk.
 The device tree binary is the last section (after which is zero padding), and it begins with the 4 byte magic |QCDT|. To extract this blob I simply used dd on the partition image skipping to whatever offset the magic was found at, and then trimming the trailing zeros similarly. This is not the most elegant of procedures, however I have not as of yet found a better way. (The correct solution I suppose would be extending the unmkbootimg utility appropriately).