single user mode?

[Anton Shterenlikht]

>From lists.br at gmail.com Sat Dec  6 14:22:54 2014
>> Is it possible to enter a single user mode
>> on arm 10.1-release?
>>
>> My disk, well.. the sd card, got corrupted,
>> so wanted to run fsck on it, but cannot
>> enter a single user mode. I ended up putting
>> the sd card into a laptop and running fsck there.
>> This fixed lots of panics, but is it possible
>> to enter the single user mode on arm, and
>> run fsck directly there?
>
>If you are using RPi with official or crochet images then yes, you can
>force it to boot in single user mode and run fsck, but (and there
>always a but) you can only do that from serial console, the vt
>framebuffer starts too late to allow you to break into loader prompt.

so I need a usb to serial converter for this, right?

Anton