How can I diagnose a startup failure on a live USB?

How can I diagnose a startup failure on a live USB?

[David Seaward]

Hi all,

I am trying to run Guix SD from a live USB on two machines. On machine
A this works: I can select "linux-libre" from GRUB and the startup
process runs, ending with a prompt on TTY 1 and documentation on TTY 2.

On machine B, the startup process runs but towards the end (ssh-
keygen... ncsd...) the screen goes black and I can't switch between
TTYs.

How can I diagnose the cause of this problem? Even enough to report an
error message.

Regards,
David

P.S. Cross-posted on Stack Exchange if you like that kind of thing:

https://unix.stackexchange.com/questions/391156

Re: How can I diagnose a startup failure on a live USB?

[Efraim Flashner]

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On Fri, Sep 08, 2017 at 03:03:24PM +0200, David Seaward wrote:
> Hi all,
> 
> I am trying to run Guix SD from a live USB on two machines. On machine
> A this works: I can select "linux-libre" from GRUB and the startup
> process runs, ending with a prompt on TTY 1 and documentation on TTY 2.
> 
> On machine B, the startup process runs but towards the end (ssh-
> keygen... ncsd...) the screen goes black and I can't switch between
> TTYs.
> 
> How can I diagnose the cause of this problem? Even enough to report an
> error message.
> 
> Regards,
> David
> 
> P.S. Cross-posted on Stack Exchange if you like that kind of thing:
> 
> https://unix.stackexchange.com/questions/391156
> 
> 

Without knowing anything about your machines, did you try the nomodeset
grub parameter? I find that normally helps with graphics issues.

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Re: How can I diagnose a startup failure on a live USB?

[Miles Fidelman]

On 9/9/17 12:50 PM, Efraim Flashner wrote:

> On Fri, Sep 08, 2017 at 03:03:24PM +0200, David Seaward wrote:
>> Hi all,
>>
>> I am trying to run Guix SD from a live USB on two machines. On machine
>> A this works: I can select "linux-libre" from GRUB and the startup
>> process runs, ending with a prompt on TTY 1 and documentation on TTY 2.
>>
>> On machine B, the startup process runs but towards the end (ssh-
>> keygen... ncsd...) the screen goes black and I can't switch between
>> TTYs.
>>
>> How can I diagnose the cause of this problem? Even enough to report an
>> error message.
>>
>>
Perhaps see if there's a way to set more verbose logging with a boot 
parameter, and find a way to capture the console messages (e.g., use a 
serial console, and a software TTY emulator).  That will at least tell 
you where things stop working.  You can start debugging from there.

A cruder approach:  On the system that works, record the sequence of 
steps that occur "towards the end."  Then work through the configuration 
of each of those steps, in turn, for the machine that doesn't work.  
(Hunch:  There's a subtle mismatch between configuration and the 
underlying hardware.)

Miles Fidelman

-- 
In theory, there is no difference between theory and practice.
In practice, there is.  .... Yogi Berra

Re: How can I diagnose a startup failure on a live USB?

[Maxim Cournoyer]

Miles Fidelman <mfidelman@meetinghouse.net> writes:

> On 9/9/17 12:50 PM, Efraim Flashner wrote:
>
>> On Fri, Sep 08, 2017 at 03:03:24PM +0200, David Seaward wrote:
>>> Hi all,
>>>
>>> I am trying to run Guix SD from a live USB on two machines. On machine
>>> A this works: I can select "linux-libre" from GRUB and the startup
>>> process runs, ending with a prompt on TTY 1 and documentation on TTY 2.
>>>
>>> On machine B, the startup process runs but towards the end (ssh-
>>> keygen... ncsd...) the screen goes black and I can't switch between
>>> TTYs.
>>>
>>> How can I diagnose the cause of this problem? Even enough to report an
>>> error message.
>>>
>>>
> Perhaps see if there's a way to set more verbose logging with a boot
> parameter, and find a way to capture the console messages (e.g., use a
> serial console, and a software TTY emulator).  That will at least tell
> you where things stop working.  You can start debugging from there.

+1. You could also probably get by via SSH. Check the output of `dmesg'
from there. I had a system recently which would blackscreen on me at the
login screen. The issue was related to the amdgpu driver (nothing to do
with GuixSD though, that was on Debian).

Good luck!

Maxim