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Old 01-19-2011, 03:52 PM
Mark Shields
 
Default Find root partition

On Thu, Jan 20, 2011 at 11:02 AM, Matthias Fechner <idefix@fechner.net> wrote:


Dear list,



I switched now to a new mainboard and it seems that the drive numbering

changed or my kernel does not detect any hard disks...

If I try to boot my gentoo the kernel panic because it cannot find the

root partition.



After the panic I cannot scroll up to check what drives are detected and

which numbering is used. What must I do to be able to scroll up to see

what is logged to the screen?

(is there maybe a special key available, the shift+page-up and scroll is

not working)



Thanks

Matthias



--



"Programming today is a race between software engineers striving to

build bigger and better idiot-proof programs, and the universe trying to

produce bigger and better idiots. So far, the universe is winning." --

Rich Cook



Your best bet is to boot from a livecd or gentoo minimal, and run fdisk -l to show the disk/partition listing.
Also, as Neil stated, make sure your new SATA chipset drivers are compiled into the kernel and not as a module; however, it you switched from say, for example, and nvidia-based motherboard to another nvidia-based motherboard, then you don't need to worry about that.
 
Old 01-19-2011, 04:22 PM
Alex Schuster
 
Default Find root partition

Matthias Fechner writes:

> I switched now to a new mainboard and it seems that the drive numbering
> changed or my kernel does not detect any hard disks...
> If I try to boot my gentoo the kernel panic because it cannot find the
> root partition.
>
> After the panic I cannot scroll up to check what drives are detected and
> which numbering is used. What must I do to be able to scroll up to see
> what is logged to the screen?
> (is there maybe a special key available, the shift+page-up and scroll is
> not working)

I don't think that's possible. But maybe adding a 'vga=ask' to the boot
parameters gives you enough lines without need to scroll?

Wonko
 
Old 01-19-2011, 05:23 PM
Jarry
 
Default Find root partition

Matthias Fechner writes:


I switched now to a new mainboard and it seems that the drive numbering
changed or my kernel does not detect any hard disks...
If I try to boot my gentoo the kernel panic because it cannot find the
root partition.


Did you recompile kernel to support your new mobo?


After the panic I cannot scroll up to check what drives are detected and
which numbering is used. What must I do to be able to scroll up to see
what is logged to the screen?


I tell you what I did in similar situation: I simply recoreded screen
during boot-up with a camera. After that, I played the video-file on
different computer, checking for messages. It is not "clean" solution,
but it worked for me... :-)

Jarry


--
__________________________________________________ _____________
This mailbox accepts e-mails only from selected mailing-lists!
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Old 01-20-2011, 02:35 AM
John Campbell
 
Default Find root partition

On 01/20/2011 08:02 AM, Matthias Fechner wrote:
> Dear list,
>
> I switched now to a new mainboard and it seems that the drive numbering
> changed or my kernel does not detect any hard disks...
> If I try to boot my gentoo the kernel panic because it cannot find the
> root partition.
>
> After the panic I cannot scroll up to check what drives are detected and
> which numbering is used. What must I do to be able to scroll up to see
> what is logged to the screen?
> (is there maybe a special key available, the shift+page-up and scroll is
> not working)

You didn't mention whether you were using lilo or grub to boot.

If you're using grub you can use the grub shell to figure that out. At
least to the which are detected and numbering phase.

I had that problem or something similar some time ago when updating to
the new, at the time, pata drivers. I ended up using a brute force
technique... I booted grub to it's built in shell and used it's limited
tools to figure out which partition/drive was which and editing the
kernel/initrd lines to get the system to boot to init level 1 and then
make the changes permanent in grub and fstab.

Probably an easier method would be to use a livecd. Just edit the grub
menu.lst file and fstab to match your new layout. Or change the
device.map to match the old layout.
 
Old 01-20-2011, 05:49 AM
Matthias Fechner
 
Default Find root partition

Hi,

On 20.01.11 04:35, John Campbell wrote:

I had that problem or something similar some time ago when updating to
the new, at the time, pata drivers. I ended up using a brute force
technique... I booted grub to it's built in shell and used it's limited
tools to figure out which partition/drive was which and editing the
kernel/initrd lines to get the system to boot to init level 1 and then
make the changes permanent in grub and fstab.


ok, I found now the problem, it was a combination of a missing driver
and a new device name (changed from sdc to sde).


But really it cannot be that it is impossible to scroll the kernel
messages up? Is there really no way existing to get to the message above?
And take a camera is absolutely impossible, from grub to kernel panic it
takes around 1 second, that is faster then the display to switch the to
the correct output mode.


Bye,
Matthias

--
"Programming today is a race between software engineers striving to
build bigger and better idiot-proof programs, and the universe trying to
produce bigger and better idiots. So far, the universe is winning." --
Rich Cook
 
Old 01-20-2011, 08:28 AM
Neil Bothwick
 
Default Find root partition

On Wed, 19 Jan 2011 19:35:09 -0800, John Campbell wrote:

> > After the panic I cannot scroll up to check what drives are detected
> > and which numbering is used. What must I do to be able to scroll up
> > to see what is logged to the screen?
> > (is there maybe a special key available, the shift+page-up and scroll
> > is not working)

> If you're using grub you can use the grub shell to figure that out. At
> least to the which are detected and numbering phase.

The GRUB setting is fine, the kernel has to load to be able to panic.


--
Neil Bothwick

"Ubuntu" is an ancient African word, meaning "I can't configure
Slackware".
 
Old 01-20-2011, 09:23 AM
du yang
 
Default Find root partition

On Thursday 01/20/11 00:52:40 CST, Mark Shields wrote:
> On Thu, Jan 20, 2011 at 11:02 AM, Matthias Fechner <idefix@fechner.net> wrote:
>
> Dear list,
>
> I switched now to a new mainboard and it seems that the drive numbering
> changed or my kernel does not detect any hard disks...
> If I try to boot my gentoo the kernel panic because it cannot find the
> root partition.
>
> After the panic I cannot scroll up to check what drives are detected and
> which numbering is used. What must I do to be able to scroll up to see
> what is logged to the screen?
> (is there maybe a special key available, the shift+page-up and scroll is
> not working)
>
> Thanks
> Matthias
>
> --
>
> "Programming today is a race between software engineers striving to
> build bigger and better idiot-proof programs, and the universe trying to
> produce bigger and better idiots. So far, the universe is winning." --
> Rich Cook
>
>
> Your best bet is to boot from a livecd or gentoo minimal, and run fdisk -l to
> show the disk/partition listing.
>
> Also, as Neil stated, make sure your new SATA chipset drivers are compiled into
> the kernel and not as a module; however, it you switched from say, for example,
> and nvidia-based motherboard to another nvidia-based motherboard, then you
> don't need to worry about that.

Yes, to boot from a livecd is a easier way to found a booting problem.

After boot from livecd, any partition can be mounted to check the contents.

And also you could recompile the kernel and install packages after mounting all the required partition and a chroot operation.

--
oooO:::::::::
(..):::::::::
:.(:::Oooo::
::\_):..)::
::::::./:::
:::::_/::::
 
Old 01-20-2011, 09:45 AM
Alan McKinnon
 
Default Find root partition

Apparently, though unproven, at 08:49 on Thursday 20 January 2011, Matthias
Fechner did opine thusly:

> Hi,
>
> On 20.01.11 04:35, John Campbell wrote:
> > I had that problem or something similar some time ago when updating to
> > the new, at the time, pata drivers. I ended up using a brute force
> > technique... I booted grub to it's built in shell and used it's limited
> > tools to figure out which partition/drive was which and editing the
> > kernel/initrd lines to get the system to boot to init level 1 and then
> > make the changes permanent in grub and fstab.
>
> ok, I found now the problem, it was a combination of a missing driver
> and a new device name (changed from sdc to sde).
>
> But really it cannot be that it is impossible to scroll the kernel
> messages up? Is there really no way existing to get to the message above?
> And take a camera is absolutely impossible, from grub to kernel panic it
> takes around 1 second, that is faster then the display to switch the to
> the correct output mode.

The whole point of a panic is that the kernel stops executing code. It has to,
something has gone badly wrong and it's too risky to continue execution of
anything.

Scrolling up involves running some code. You can't have it both ways.

--
alan dot mckinnon at gmail dot com
 
Old 01-20-2011, 11:29 AM
Matthias Fechner
 
Default Find root partition

Hi,

On 20.01.11 11:45, Alan McKinnon wrote:

The whole point of a panic is that the kernel stops executing code. It has to,
something has gone badly wrong and it's too risky to continue execution of
anything.

Scrolling up involves running some code. You can't have it both ways.


yes, you can see it that way
(but on my eyes, not finding the root partition, is not such a critical
problem to stop everything )


Thanks all for your comments, the problem is solved now and the open
point is not really a gentoo problem.


Bye,
Matthias

--
"Programming today is a race between software engineers striving to
build bigger and better idiot-proof programs, and the universe trying to
produce bigger and better idiots. So far, the universe is winning." --
Rich Cook
 
Old 01-20-2011, 03:13 PM
Jarry
 
Default Find root partition

On 20. 1. 2011 7:49, Matthias Fechner wrote:


And take a camera is absolutely impossible, from grub to kernel panic it
takes around 1 second, that is faster then the display to switch the to
the correct output mode.


Remember, nothing is impossible! "Impossible" only takes
two more days of effort, compared to "possible"...

I had a movie-camera in mind of course (or photo-camera with
ability to record movies). You turn it on, point on screen,
start recording, and after that turn computer on. If it can
record at least 20fps (my cheap digi-camera can make 60fps),
it would capture all messages. They would be a little unsharp,
but still clear enough to read them.

Jarry

--
__________________________________________________ _____________
This mailbox accepts e-mails only from selected mailing-lists!
Everything else is considered to be spam and therefore deleted.
 

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