Qubes RAM Issue


I have a system with 16GB of RAM, but Qubes is only recognizing 4GB of RAM in existence. Why would this be? Why can’t it see the entire RAM space?

Thank you

I suspect you mean that dom0 only sees 4GB.
This is set in boot parameters - check the value of dom0_mem=max in
the parameters in grub.cfg

The rest of the RAM is allocated to the qubes.
You can alter the amount allocated to dom0 by editing that parameter -
there’s little point is giving dom0 4G if you have 16GB total. I run my
system with max 1536M - ymmv

I never presume to speak for the Qubes team.
When I comment in the Forum or in the mailing lists I speak for myself.
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How much RAM is recommended for just dom0 please?

See my reply - that works for me.

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How do you get at this (dom0_mem=max) setting when using UEFI? There is no grub.cfg

I’m rather thick when it comes to anything core that is non gui so baby steps please!

image [1]

  1. screenshot from a live usb, not visible while using qubes ↩︎

@ppc any chance of the path to that file? Either it doesn’t exist or I’m looking in the wrong place (and the odds would favour the latter).


depend on how you like to access the file

Lets go with CLI. A simple path would be great.

on qubes installer, right? if so

then chose to mount your qubes install
after that cd /mnt/sysimage/boot/grub2
nano grub.cfg

The journey continues to be unnecessarily arduous.

Steps that I am taking:

I boot from the installer usb
I switch into rescue mode
I enter my LUKS password
I am told that I don’t have any linux partitions
In the shell, the only thing in /mnt/ is ‘install’, which is a dir. It contains only cmdline.d, isodir and repo
In /boot/ there is onlt initramfs-5.4.98-1.fc24.qubes.x86_64.img

I must be doing something wrong, but I can’t see where I’m deviating from the manual

so does you have any live disk?
(i remember i also met this problem and i was use windows pe to fix it)

I was accessing the disk through the QubesInstaller.

You are saying now I need to use windows?!

I’m just trying to put some limits on the Dom0 ram allowance.

it my experience
try some linux distro live disk first
windows would only be the last option

In UEFI systems, you’ll find some .conf files somewhere in /boot/loader that contain the kernel command line. That is where you change the things in question.

Can I get to those files through Dom0? Or do I still need to mount the disk from a live disk?


No such file.

/boot/ contains:
grub/ ← nothing major here
grub2 ← nor here

There is a file called xen.4.8.5-36.fc25.config

This is becoming exceedingly vexing

Of course you can, I have no clue why would anyone suggest to boot with a rescue disk.

Unless of course your boot drive is on an USB stick, and the USB stick got “removed” from dom0 when you booted. (This is bad practice by the way, and to be frank this would easily explain your trouble).

All Qubes systems have a /boot which contains files, and most will have stuff in /boot/loader and /boot/efi. If yours doesn’t, and the USB disk situation is not part of the problem, I don’t know what to tell ya.

It would help if you took a photo of the output of mount on the dom0 terminal.