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I'm trying to root my N4, and fastboot doesn't seem to work. Running it on linux, and the fastboot binary seems to run.

'Fastboot devices' produces info on my device, but 'fastboot oem unlock' just echoes '...' and hangs. I don't get the prompt on the phone about unlocking. It just hangs there until I restart the bootloader, at which point fastboot echoes "FAILED (command write failed (Cannot send after transport endpoint shutdown)"

Other fastboot commands don't seem to work either. 'fastboot reboot' echoes 'rebooting...' but then nothing happens.

I've tried this with and without usb debugging enabled. Any ideas?

I'm beginning to think the USB port(s) on my machine may be blown. This morning, the machine didn't recognize an iPod plugged in under Windows on either the front or back USB ports on my machine. I'm working on the phone under Linux, and /var/adm/messages shows stuff happening when I plug the device in. I'm guessing 'fastboot devices' doesn't acutally access the device - just looks at the device types detected by the OS when you plugged it in, no? Is it possible I can read from the usb port but can't write to it?

Well, it looks like it was my USB ports. I found an old laptop, booted it up to a Ubuntu live CD, and was able to root the phone from there. Sorry for all the drama. Odd that my USB ports died just at this moment, but come to think of it, they've been running slow recently - gPodder had been taking minutes to copy podcasts to my iPod. I guess it was a gradual fail.

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Try running fastboot as root (sudo fastboot devices) –  Liam W Jan 5 '13 at 20:00
    
Nope, sudo doesn't help. For what it's worth, I did a tail -f on /var/log/messages when I started the bootloader. Output below, ending with the SerialNumber, which matches what 'fastboot devices' prints. –  littlenoodles Jan 5 '13 at 21:30
    
The /var/log/messages stuff is too long to be input here. But it basically tries and fails to detect it as a usb 3-5 device, then tries as usb 2-2 and succeeds. –  littlenoodles Jan 5 '13 at 21:36
    
localhost klogd: usb 2-2: new full speed USB device using ohci_hcd and address 6 localhost klogd: usb 2-2: New USB device found, idVendor=18d1, idProduct=4ee0 localhost klogd: usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 localhost klogd: usb 2-2: Product: Android localhost klogd: usb 2-2: Manufacturer: Google localhost klogd: usb 2-2: SerialNumber: 006ef4fae094444f –  littlenoodles Jan 5 '13 at 21:37
    
One more (odd?) thing. I tried to select recovery from the bootloader, and it went to a frozen recovery screen with the message "no command found". Is that scary? From there I was able to get back to the bootloader again with the vol-down, power combo. –  littlenoodles Jan 5 '13 at 22:02
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1 Answer

The clue lies with the comment above But I just tried 'adb reboot bootloader', and it worked. which shows that adb is indeed recognizing the USB connection, but not in fast-boot mode which is where this answer comes in...

Sounds like the udev rule for the fast-boot is absent!

Do this: lsusb with the cable plugged in while the handset is in fast-boot mode.

Typical output should be one similar to this:

Bus 001 Device 012: ID 18d1:d00d Google Inc.

                     ^^^^ ^^^^

The numbers identifier 18d1:d00d corresponds to idVendor : idProduct respectively.

Make note of it, and check your udev rules found in /etc/udev/rules.d/51-android-rules. (Mileage will vary slightly with differing Linux distributions!)

If you do not have this file, then its recommended to create one using root, there may be a few rules that need to be added depending on the mode of the handset, i.e. normal, recovery and boot-loader modes.

Here's an example of mine, that has differing values respectively when handset is in one of these modes. Take this as a template and change the numbers as shown that matches up with idVendor and idProduct respectively to suit your make/model of handset.

SUBSYSTEMS=="usb", ATTRS{idVendor}=="19d2", ATTRS{idProduct}=="1354", MODE="0666" GROUP="androiddev", SYMLINK+="android%n"
SUBSYSTEMS=="usb", ATTRS{idVendor}=="19d2", ATTRS{idProduct}=="1350", MODE="0666" GROUP="androiddev", SYMLINK+="android%n"
SUBSYSTEMS=="usb", ATTRS{idVendor}=="19d2", ATTRS{idProduct}=="1351", MODE="0666" GROUP="androiddev", SYMLINK+="android%n"
SUBSYSTEMS=="usb", ATTRS{idVendor}=="18d1", ATTRS{idProduct}=="d00d", MODE="0666" GROUP="androiddev", SYMLINK+="android%n"

The user id is added to the androiddev group, which was created on previous occasion, in that way I do not have to sudo at all!

To create a group, using root

  1. groupadd androiddev, this creates a group, then to add your linux's user id to that group...
  2. usermod -a -G androiddev your_user_id; replace your_user_id with your own user id used for logging in).

Then when in fast-boot mode, the fastboot binary should work (bonus! without the necessitating for sudo either!)

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