Hi

I have a USB stick with a centos 7 iso on it and am trying to install it using a machine with libreboot.

I have previously used this USB stick to install centos on a bios machine.

However when I attempt to do so on my machine with libreboot I get an error message:
DMAR: Failed to map dmar2

Does anyine know what I need to do to install centos 7 using a machine with librebot ?

Anyone any idea what this error message means ?

Hi:

Until today I had never heard of libreboot so I looked it up to find out more and it's a free (as in freedom) BIOS or UEFI replacement.
https://libreboot.org/

I tried going to the Wikipedia page to find out more info on Libreboot but it wouldn't let me read the article w/o giving Wikipedia a donation:-


Did you install libreboot or did it come with the machine?
Have you found a way to get into libreboot to look at the settings?

In this search there are several solved answers to the error message you are getting.
https://www.google.com/search?client...67.6-XBNnsLgBQ

No, but I found 2 links that teach you how to stop the error from showing up.

This link will tell you more about the error:

https://lists.gnu.org/archive/html/l.../msg00014.html

https://bbs.archlinux.org/viewtopic.php?id=205008

You may also want to list your machines specs.
-:::-Knowing the exact make and model could lead us to a SOLVED thread:-

Modifying the GRUB Configuration in Libreboot

https://libreboot.org/docs/gnulinux/grub_cbfs.html

This should work "Install Centos 7 with libreboot"
https://stigatle.no/index.php/2018/0...ith-libreboot/


IF that fails try here:

When you use Libreboot’s default GRUB config, and libreboot-grub uses fedora’s default grub.cfg (in /boot/grub2/grub.cfg), see instructions here:

https://libreboot.org/docs/gnulinux/

Thank you very much for your replies.

> Did you install libreboot or did it come with the machine?
libreboot came installed with the machine and thus far I also know nothing about it.
I thought someone might know something about it, or maybe had instaled centos on a machine with it

> Have you found a way to get into libreboot to look at the settings?
I can get in to the menu and edit grub and I did try putting intremap=off on the boot line which did not work, though with that option I did not see the DMAR: Failed to map dmar2 error message, I simply get a message saying 'Invalid ROM contents'
Just to check that I am editing the command line correctly:
In the grub config I am changing the line:
linux$linux_suffix '/isolinux'/'vmlinuz' initrd=initrd.img inst.stage2=hd:LABEL=CENTOS\x207\x20X8 quiet
to
linux$linux_suffix '/isolinux'/'vmlinuz' initrd=initrd.img intremap=off inst.stage2=hd:LABEL=CENTOS\x207\x20X8 quiet
Is that correct ?

Just to note some of the links I have seen regarding this message suggest that centos still installs when they see it - this is not the casae with me in this instance - it eventually times out and drops in to an emergency shell.

Still looking at the links regarding centos and libreboot - have not been able to get much extra out of them so far.

Yes, that's correct:-

If you keep having time outs that drop into an emergency shell you might want to install Centos exactly the way it says to in the link in post #3.

Does your pc met the computer requirements for Centos?
Enough RAM and CPU?

https://www.ionos.com/digitalguide/s...-requirements/

https://www.centos.org/forums/viewtopic.php?t=49507

Did you check the integrity of the .iso of CentOS before making the usb stick bootable?

what does the lines above the last line say? There might be the clue to why the installer is dropping to emergency mode.

Currently having problems bringing the install back up - it seems libreboot is no longer recognising the USB stick as bootable. I'll re-mage and try again and post back when I can get the information.

https://www.kernel.org/doc/Documenta...ntel-IOMMU.txt for clues.

OK it looks like I grabbed the wrong usb stick the other day.

Thank you for your replies

To answer a few questions:
> Did you check the integrity of the .iso of CentOS before making the usb stick bootable?
I have used this iso to fully install centos 7 on other systems - it works.

> what does the lines above the last line say? There might be the clue to why the installer is dropping to emergency mode.
Failed to switchroot: specified switch root path /sysroot does not seem to be an OS tree. os-release file is missing.
....
Failed to switch root


#systemctl status initrd-switch-root.service
...
Active: failed (Result: exit-code) .....
Process 3997 ExexStart=/usr/bin/systemctl --no-block --force switch-root /sysroot (code=exited, status=1/FAILURE)


> Does your pc met the computer requirements for Centos?
It's listing 2 cpus:
Intel(R) Core(TM)2 CPU P9600 @ 2.53G

not sure if that is sufficient

There is just under 4G of RAM.

Can't immediately a site which succinctly lists the system requirement, so will check this later.

Not sure if the install is getting far enough to be affected by these.

> If you keep having time outs that drop into an emergency shell you might want to install Centos exactly the way it says to in the link in post #3.
Not sure exactly which link you are referring to.
I have been doing the installation as described in this link
https://libreboot.org/docs/gnulinux/...installer.html

though I have not tried to go through this section yet:
> Booting ISOLINUX Images (Manual Method)
So will give that a go
(Although I think this is just if the install is unable to start at all)

try changing to
or what /dev/??? the iso is located on?

Hi

Thank you again for the replies and apologies for the delay, I've only just managed to get back on to this after the Christmas break.

I finally managed to get centos 7 installed to another USB by:

A.

Boot the libreboot machine with the installation USB plugged in to my usb hub

edit grub command line:
replace
inst.stage2=hd:LABEL=CENTOS\x207\x20X8
with
inst.stage2=hd:/dev/sdb1
(and also including the intremap=off to get rid of the DMAR error)

press F10 to boot

Work through centos 7 installation wizard:
When selecting installation media insert USB stick to usb hub, select 'Refresh'.
New USB is detected and given as an option for installation device - select it and wipe clean when requested.
Continue through installation
(Note: when I attempted to create a user during installation process it hung - not sure why, so after that I only set a root password)


B.
Insert USB and into bios machine and boot from the live usb just created

Edit the grub config as suggested in the link https://libreboot.org/docs/gnulinux/ under 'Fedora won’t boot?':
Open /etc/grub.d/10_linux

Set the sixteenbit variable to an empty string, then do:

grub2-mkconfig -o /boot/grub2/grub.cfg

C.
Insert live usb in libreboot machine and Boot to usb

edit grub command line (as previusly):
replace
inst.stage2=hd:LABEL=CENTOS\x207\x20X8
with
inst.stage2=hd:/dev/sdb1
(and also including the intremap=off to get rid of the DMAR error)

F10 to boot

Centos installed on the USB stick now comes up

Thank you all for your help.


A couple more questions came up while I was doing this:
1. what does hd:LABEL=CENTOS\x207\x20X8 and where does it come from ? How does is reference the usb device ?

2. In order to edit the grub configuration I had to boot up on a bios machine to edit the .cfg file and run grub2-mkconfig script. Does anyone know if there is any way of doing this directly when booting up ? (maybe from some sort of grub prompt ?)

3. When I included the GUI in the install (I am doing this to check my touchpad with a different OS) I wanted to boot directly in to the command line to edit the grub config, so I booted in to single user mode by replacing 'ro' in the grub config with 'rw init=/sysroot/bin/bash', boot, then 'chroot /sysroot'.

However I was unable to see any files or dirs in /boot when doing this. Does anyone know why that is ?

With centos 6 I seem to remember you can simply change the runlevel from the grub command line. Can you do that with centos 7 ?

1 members found this post helpful.

I think the installer was looking for a partition labeled CENTOS\x207\x20X8, I didn't know if your sdb1 was labeled as such.
at the grub menu you can hit the e for edit and make temporary changes to get booted into the system

Thanks for your help colorpurple21859-

your Welcome

1 members found this post helpful.