Install Proxmox VE on eMMC

Recently I bought a mini PC looking forward to setting up a home router. It started quite well except the specs were higher than I anticipated. 8 GB RAM plus 128 GB eMMC - too much waste for “just a router”, so I figured I’d get some virtual machines to improve its utilization. Choosing the virtualization platform isn’t hard - I’m most familiar with Proxmox VE.

The offcial ISO installer is pretty straightforward, until the last step:

Unable to get device for partition 1 on device /dev/mmcblk0

Solution

The Proxmox VE forum is completely unhelpful this time (1, 2) with staff keeping on saying “it’s not supported”, so I had to look around for alternatives. Fortunately this article is right there (for Proxmox VE 7):

• 解决 Proxmox VE 无法安装到 eMMC 上的问题 - lookas2001

Turns out it’s hard-coded into Proxmox VE’s Perl installer script, so all you have to do is to patch it:

1. Boot the installer ISO to the first menu, select the second option Install Proxmox VE (Debug mode)
2. The first time you’re present with a command-line prompt, type exit and Enter to skip it. This is a very early stage and you can’t do much here.
3. The second time you have a shell, locate /usr/share/perl5/Proxmox/Sys/Block.pm¹ (for Proxmox VE 8) and open it. Text editors such as vi and nano are available.

4. Search for unable to get device and you should find some code like this:

    } elsif ($dev =~ m|^/dev/[^/]+/hd[a-z]$|) {
        return "${dev}$partnum";
    } elsif ($dev =~ m|^/dev/nvme\d+n\d+$|) {
        return "${dev}p$partnum";
    } else {
        die "unable to get device for partition $partnum on device $dev\n";
    }
   

   The full code can be found on GitHub if you’d like.

5. See how different kinds of storage devices are enumerated? Now add /dev/mmcblk to the list like this:

    } elsif ($dev =~ m|^/dev/[^/]+/hd[a-z]$|) {
        return "${dev}$partnum";
    } elsif ($dev =~ m|^/dev/nvme\d+n\d+$|) {
        return "${dev}p$partnum";
    } elsif ($dev =~ m|^/dev/mmcblk\d+$|) {
        return "${dev}p$partnum";
    } else {
        die "unable to get device for partition $partnum on device $dev\n";
    }
   

6. Save your edits and type exit. Proceed with the installation as normal. Select /dev/mmcblk0 (without the bootX suffix) as the install target. You may want to disable swap to avoid rapid wearing of the eMMC.
7. The next time you have a shell, use exit to skip it. Nothing to do here.

Rambling

While it’s possible to install Proxmox VE on top of a matching version of Debian, it’s tedious to install Debian just for PVE. The last time I had to do it this way was on very old hardware that the PVE installer just crashed (X server died), and that the PVE installer didn’t have a CLI version. Plus a standard Debian installation typically comes with extra stuff that you don’t want on a PVE system (or want to get rid of ASAP).

It’s also possible to modify the installer script beforehand, but you need to unpack pve-installer.squashfs and re-pack it into the ISO. You should think more seriously if you want to install PVE on a lot of eMMC devices.

1. For Proxmox VE 7, you should go for /usr/bin/proxinstall instead. ↩