Nexus one linux console?

[ronubo]

Hi all,
Is there anyway to achieve a linux console on the nexus one, during BOOT time?

My intent is to see the kernel log messages during android boot, as I would if I set
up an embedded linux platform, hooked a serial to its e.g. /dev/ttyS0, and connected to
it from a serial terminal (e.g. CuteCom, Procomm, Windows HyperTerminal etc.).

Is this achievable using the "regular" (micro USB to USB) cable, or should there be some dedicated cable?

Can someone please tell me how this can be done? I am sure there is a neat method to do so, I just haven't figured out how, from the current stuff I have read.

Thanks,
Ron.

[danger-rat]

There's a couple of apps by Chainfire on the Market which run live dmesg and logcat streams as boot animations, so it's probably possible, but how you would go about achieving it is beyond my Android Fu...

Chainfire is an xda user, so you may be able to track him down.
If you succeed, I'd be interested to know the answer... xD

[ronubo]

The thing is, that I'm looking for the "console" support on android bootstrap. I'm looking
at it as an embedded linux developer, as in "What do I do if my kernel does not boot up"?
In this case I will never even get to a "logcat", or "dmesg" state.

I would like to see the infamous "uncompressing linux..." message.

When an embedded linux, such as android comes up, its sequence would usually be something like this:

0. Power up - CPU jumps to a well defined, hardcoded addres, where the first "bootloader" is stored.
1. bootloader does its magic: Sets up DRAM controllers, sets up execution environment (e.g. making "C" code possible, by preparing stack region etc, and allowing some more bootloader code to be written in a non-assembly language,
2. bootloader setups "console" - e.g. setup UART - and in the the Nexus I would expect (or hope?) to have it set up something on the USB port. What is this thing? I have no clue
3. Fetch/decompress/boot kernel - here, assuming a "console" was set up before, a "console=..." argument can be given to the kernel as an argument.

Now the question is how do these things work with Nexus-One specifically.
Do you think the XDA forum would be a better place to ask?
My previous "low-level" questions remained unanswered :-/


Thanks,
Ron

[af3556]

Originally Posted by ronubo

The thing is, that I'm looking for the "console" support on android bootstrap. ...
2. bootloader setups "console" - e.g. setup UART - and in the the Nexus I would expect (or hope?) to have it set up something on the USB port. What is this thing? I have no clue
...

Check the XDA thread:
232 - serial - USART - UART - xda-developers

"TTL level (~3.3v?) serial is present on the D+/D- pins of the micro USB connector whenever VBUS (usb +5v power) is not present. This is physical UART1 (ttyMSM0)"