New beginners guide

I took nabax' beginners guide [1] and added it to eLinux wiki

Please feel free to correct, improve and add additional links.

Many thanks for this



Hi, Dirk,

The bootargs have 'rootdelay=1'. Why we need this? Will this number change
if we have a bigger rootfs?



Geof wrote:


Great idea. I have listed some specific comments below. This is a
fantastic idea.

- Serial Connection: Rather than drilling out the 10-pin connector, I
would recommend using a needle-nose pliers and breaking off pin 10 on
the beagle board. It is not connected electrically to anything. The
cable only has 9 wires in it. So pin 10 is completely unused at both
ends of the cable. It is clearly marked pin 10. In this way, you are
also sure that you are not plugging the cable on backwards. So the
blocked 10th pin has a purpose. And a few bends back and forth and
the pin snaps right off.

- I have a question: Why is it important to set the number of heads,
sectors and cylinders when formatting the SD card? I used a 2MB card,
and just set the first partition to be +256M, and then let the second
partition be the rest of the disk. I'm just curious if there is a
performance advantage etc? Thanks for your advice here. I just used
whatever head/sector/cylinder counts were the default. Do I need to
go back and re-do?

- You may want to warn people on the tar xvjf... -- 1) do not untar to
somewhere else and then cp the results. You must untar directly onto
the SD card. 2) It will take quite a while. So be patient.

- You may want to add some commentary (assuming that with Angstrom
people will want to be USB OTG in Host mode) that describes the
special cable adapter needed to connect a USB Hub to the card. For
example: "If you would like to use the Beagle as a "USB Host" (i.e.
to connect a USB hub to the board), then you must connect a "USB Mini-
A" plug into the OTG receptacle on the board. Almost every cable that
is out there that has a USB mini is a USB mini-B and this will not
work. A suggestion is to get a normal USB 2.0 Hub -- it will have a
cable with a USB Standard-A Plug on the end that would normally plug
into a PC. Then purchase separately a USB-Standard-A-Receptacle to
USB Mini-A-Plug Adapter (these are hard to find). But some sources

- One area that I am very interested in (but don't have a solution for
yet) is connecting up a USB WiFi Adapter to the USB Hub. If you have
any recommendations as to what hub has appropriate Linux drivers
available, that would be awesome.

I hope this is helpful. Your manual is very much needed.

Thanks very much.

Best regards,
Geof Cohler

Thanks to nabax! This guide isn't from me, I just copied nabax' text to eLinux wiki.

Regarding your questions, I'm adding beagle list, there are more people able to help/answer.

Regarding your comments, well, eLinux is a wiki, everybody can add content. Maybe you like to directly add your improvements there?

Many thanks for your feedback!


Guo Tang wrote:

Hi, Dirk,

The bootargs have 'rootdelay=1'.

Thanks for the hint. Replaced it by rootwait. Rootwait will always
wait as long as necessary.

Why we need this?

Seems that it needs some delay until root fs at MMC is accessible.

Will this number change
if we have a bigger rootfs?

Not sure. Using rootwait this will wait as long as necessary. Does
Google help you regarding this?


This a delay is used when using a mmc based devices as root file
system. The mmc layer performs the partition detection in the
background and when time comes to mount the root file system you still
might have to wait.This mainly depends on the boot speed of the kernel
and the speed of the mmc initilsation , not the size of the rootfs.

I see that a great part of the guide goes about telling how to
configure minicom. Myself I always use
picocom and invoke it with -b 115200 /dev/ttyS0 or ttyUSB1

The most intriguing part for me is the formating of the disk. I did
not use CHS on my card and I wonder why
should enter the expert mode. does anybody have a good explanation?


Rootwait was introduced in 2.6.24, so the TI .22 kernel would still
need rootdelay.



The ROM loader needs/expects a specific CHS setup, maybe your card
already had the one it expected.



"Kees Jongenburger" <> writes:

When I first got my BB it took a bit of banging my head against the
wall/desk/floor before everything sprang into life, and the culprit
was the partition table on my SD card: In my excitement on
downloading things I fdisked my SD card like I have a hundred times
before, made filesystems, etc. and booted. What I found was that my
rootfs would mysteriously start to fall apart or access locking up;
the clues came when I started to get a lot of "attempt to access off
end of device" errors. My partitions were screwed, and my root
filesystem turned out to be slightly too large for the SD card. (u-
boot was fine with the FAT part1, & I was just using it for root, not
doing MMCBoot stuff.)

I had of course skimmed the docs and not performed this step of
setting the disk geometry in fdisk; so I think it might be that some
cards report something sensible but my card caused fdisk to do
something very weird. (63C/255H is LBA mode, isn't it? Wouldn't want
anything else..)

So that section could do with being in super bold for people like me
(as in, "This may seem superfluous but really, just try it!") :wink:



PS: Thanks to Geraint North for following the directions and pointing
out my cut corner. :slight_smile: