[yocto] meta-cedartrail - serial console

[Darren Hart]

On 06/01/2012 08:45 AM, jfabernathy wrote:
> On 05/31/2012 03:41 PM, Darren Hart wrote:
>>
>> On 05/31/2012 11:54 AM, jfabernathy wrote:
>>> On 05/31/2012 02:13 PM, Darren Hart wrote:
>>>> On 05/31/2012 09:11 AM, jfabernathy wrote:
>>>>> Using a DN2800MT (Marshalltown) Intel board, I'm testing the
>>>>> meta-cedartrail using edison branch and noticed an issues with the
>>>>> serial console.
>>>>>
>>>>> The cedartrail.conf in the machine directory has the following statements:
>>>>>
>>>>> SYSLINUX_OPTS = "serial 0 115200"
>>>>> SERIAL_CONSOLE = "115200 ttyS0"
>>>>> APPEND += "console=ttyS0,115200 console=tty0"
>>>>>
>>>>> However, when the image booted, I had no serial console on ttyS0.  I
>>>>> checked /etc/inittab and noticed that the following line existed:
>>>>>
>>>>> S:2345:respawn:/sbin/getty 115200 ttyS3
>>>>>
>>>>> I changed the ttyS3 to ttyS0 and then I have a serial console on the
>>>>> next reboot.  So it appears the override in the .conf file is not
>>>>> working.  Also I only have the console from getty, and not the kernel
>>>>> logging console.
>>>>>
>>>>> Anyone have a solution??
>>>>>
>>>>> If this is considered a bug I can put it on bugzilla.
>>>> Lets make sure your environment is what we expect. Please provide the
>>>> output of:
>>>>
>>>> $ bitbake core-image-minimal -e | grep SERIAL_CONSOLE=
>>>>
>>>> If it is not "115200 ttyS0" then it is getting overwritten somewhere
>>>> either in your config, or possibly by an inappropriate selection of an
>>>> assignment operator (=, ?=, etc.) in edison.
>>> okay now I'm confused.  while the cedartrail.conf file has the following:
>>> SYSLINUX_OPTS = "serial 3 115200"
>>> SERIAL_CONSOLE = "115200 ttyS3"
>>> APPEND += "console=ttyS3,115200 console=tty3"
>>>
>>>
>>> The output of the bitbake command you suggested above gives:
>>> jim at ubuntu-x64:~/poky/build$ bitbake core-image-minimal -e | grep
>>> SERIAL_CONSOLE=
>>>
>>> # SERIAL_CONSOLE=115200 ttyS0
>>> SERIAL_CONSOLE="115200 ttyS0"
>>> jim at ubuntu-x64:~/poky/build$
>>>
>>> So is the bitbake command showing the results before the cedartrail.conf
>>> options take affect??
>> variable assignments can be tricky, and are not the easiest things to
>> track down. I suggest looking through your configured layers and looking
>> for all the SERIAL_CONSOLE assignments using ttyS3 and ttyS0 and see if
>> you can determine what is overriding your cedartrail.conf setting.
>>
> What I found out is the only variable that matters for login console in 
> my situation is SERIAL_CONSOLE because I have to use grub and the boot 
> from hard drive method because my image can't be put on a USB Flash for 
> some reason.  So I manually have to edit the grub.cfg file as documented 
> on the wiki "How Do I" section of putting Yocto on a hard drive.  Adding 
> console=ttyS0,115200 on the linux statement takes care of the boot console.

I believe this is a manual process currently. Please open an enhancement
in bugzilla for your specific situation and I'll incporporate into the
larger boot process and image revamp we're doing for 1.3.

> 
> So the question is has there been any thought about automating the 
> choice of boot loader and the parameters that are needed or optional?  
> In the case of meta-cedartrail, the cedartrail.conf assumes syslinux is 
> the boot loader. When I could use a USB Flash key, creating a boot 
> device was a trivial dd statement.  Because I have to use a hard drive 
> now, I have to do a number of manual steps.  Or is there a way to create 
> a boot-able hard drive with syslinux so the cedartrail.conf parameters 
> are all that is needed to adjust?

This is all good feedback to consider as we work through making more
universally bootable images. This is becoming a hot topic as people are
using Yocto in more and more situations and as things like EFI become
more commonplace.

There is no reason you can't just dd (have a look at
scripts/contrib/ddimage) the image to a hard disk instead of a usb
stick. You may need a USB to SATA adapter for your host (this is what I
use). If you have a USB port, you could just use the install option.

The integration between the boot loader options is something that needs
work. At some point I hope to replace GRUB with syslinux in all possible
situations in order simplify the option handling and present a
consistent boot interface between live images, iso limages, and disk images.

-- 
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel