With my android device attached over USB, I entered the following commands:
adb pull /dev/block/by-name/boot ./boot.img adb reboot bootloader sudo fastboot boot ./boot.img
and I received this output from fastboot:
downloading 'boot.img'... OKAY [ 0.782s] booting...
After this, nothing happens. I would expect the stock android system to boot on the device. I don't know where the boot process could have failed, since neither the device, nor fastboot is giving any useful output. My end goal would obviously be to boot modified images, but right now I can't even seem to be able to boot the stock one.
Is this supposed to work generally? If yes, what are some reasons it could have failed? Are there ways to obtain additional useful debugging information?
(My device is a low cost Allwinner A31s based tablet, so I don't expect to find any device specific help on the internet. I can't even find the website of the manufacturer.
ro.product.model= Navon_Predator_7, ro.product.device= fiber-wt7028, ro.product.name= fiber_wt7028 [I used
getprop in the adb shell to obtain these values.])
The boot image does look like it's in the android mkbootimg format (here are the first few bytes):
00000000: 414e 4452 4f49 4421 a49f 8600 0080 0040 ANDROID!.......@ 00000010: 5663 0d00 0000 0041 0000 0000 0000 f040 Vc.....A.......@ 00000020: 0001 0040 0008 0000 0000 0000 0000 0000 ...@............ 00000030: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000040: 636f 6e73 6f6c 653d 7474 7953 302c 3131 console=ttyS0,11 00000050: 3532 3030 2072 7720 696e 6974 3d2f 696e 5200 rw init=/in 00000060: 6974 206c 6f67 6c65 7665 6c3d 3420 766d it loglevel=4 vm 00000070: 616c 6c6f 633d 3338 344d 2069 6f6e 5f72 alloc=384M ion_r 00000080: 6573 6572 7665 3d31 3238 4d00 0000 0000 eserve=128M.....
ro.product.model: Navon_Predator_7, ro.product.device: fiber-wt7028, ro.product.name: fiber_wt7028(I used
getpropin the adb shell to obtain these values.)
adb pullis for files, not devices, you should be using
ddto save the boot image to a file.
adb shell dd if=/dev/block/by-name/boot of=/sdcard/boot.img, followed by
adb pull /sdcard/boot.img ./), but the problem persists. You are saying that this only works on some devices. What are some other devices where this does not work? Could you point me somewhere where reasons for a fastboot boot failing are discussed?