Why isn't Startup Manager showing Ubuntu Netboot USB - mid 2010 imac 21.5"

Question

Apologies if this question is inappropriate for this forum I am not sure whether I should be on the Apple or Ubuntu StackExchange.

I am trying to turn an iMac mid 2010 21.5" into a home server by installing Ubuntu Server 20.04 LTS on it. Startup manager is not recognising the bootable USB that has been loaded with the Ubuntu Server Netboot ISO, though it is recognising a USB that has been loaded with the standard Ubuntu USB - does anyone know why this might be? I am using the same program to create both bootable USBs and I have tried different USB ports.

For context there isn't a functioning OS on this machine. An earlier attempt to install Ubuntu Server crashed so when I boot the machine it goes to blank screen with just only '_'.

The standard Ubuntu ISO can't be installed due to a GPU issue: 'no UMS support in Radeon module' is the error that I receive and I have tried editing the GRUB settings to include 'nomodeset' as suggested on forums such as this one: E.g. Installing Linux on 2009 iMac, black screen after bootloader

What program would the "same program" be? What would the names of the ISO files? Can you give a link where you found these files? What machine are your using to make the bootable USB? How much memory is installed in the iMac? Does the Linux have to be Ubuntu? Are you choosing a server addition because you believe a graphical desktop in not possible or another reason? Do you care if the Linux uses EFI or BIOS booting. Do you care if a MBR partition scheme or GUID partitioning scheme is used? — David Anderson, Dec 24 '20 at 00:41
1.Startup Disk Creator. 2. Ubuntu netboot file is named 'mini.iso', Ubuntu server 'ubuntu-20.04.1-live-server-amd64.iso'. 3. Netboot file from link Ubuntu server file = option 3 from link . 4. Machine used to make bootable USB is running Kubuntu, has 8GB RAM and intel i5 CPU. 5. The Linux does not have to be Ubuntu though that is what I am used and there seems to be a lot of support for it. 6. I am choosing server because I want to make home server — Ambassador Kosh, Dec 24 '20 at 09:37
Mac has 4GB memory, it meets the minimum requirements for Ubuntu — Ambassador Kosh, Dec 24 '20 at 10:16
What does "server" mean? Why wouldn't you just re-install macOS (of the appropriate vintage)? — Marc Wilson, Dec 24 '20 at 22:01
So that I can host my own websites. I'd like to develop my back-end skills. — Ambassador Kosh, Dec 25 '20 at 18:29

David Anderson · Accepted Answer · 2021-01-22T15:41:32.753

The short answer is the mini.iso is bootable, just not bootable from a USB flash drive on a Mac of your vintage.

Here is some of the things I tried.

I transferred an ISO file to a USB flash drive by writing the file directly to the flash drive. So, what appears on the flash drive is exactly what exists in the file. There many ways to accomplish this. I used a Mac booted to macOS. The identifier for the flash drive was disk2. An example of the commands is given below.

diskutil unmountdisk disk2
sudo dd if=~/Downloads/mini.iso of=/dev/rdisk2 bs=1m

The same can be accomplished with Linux by entering the commands given below. Here, the identifier for the flash drive was sdc.

sudo umount /dev/sdc*
sudo dd if=~/Downloads/mini.iso of=/dev/sdc bs=1M

I found the USB flash drive created using the mini.iso file was BIOS bootable by the Startup Manager on a 2013 iMac. While I was able to boot, I choose not to install. The same flash was not detected by the Mac Startup Manager on a 2007 iMac. This is expected, since iMacs could not BIOS boot from flash drives until at least after the 2011 model year. Neither Mac Starup Manger could detect a EFI boot file on the flash drive, even though such files do exist on the flash drive. I state this because the flash drive can EFI boot in a VirtualBox virtual machine on the 2013 iMac running Catalina. I was able to install Ubuntu 18.04.5 LTS on the virtual machine.

I used the same method to transfer the ubuntu-20.04.1-live-server-amd64.iso file to a flash drive. This was detected as EFI bootable by the Mac Startup Manager on the 2007 iMac. I was able to boot and installed an Ubuntu server. A present, the Mac Startup Manger is needed to boot Ubuntu server on the 2007 iMac. I have not tried fix the Mac to boot Ubuntu server as the default operating system. I should also point out that this version of Ubuntu server boots to a command line interface (CLI).

Next, I tried using the Startup Disk Creator that comes with kubuntu. This basically does the same thing as the dd command used above.

When installing Ubuntu Server, I made the following selections.

I chose to update to the new installer.
I chose to not use the entire disk without a LVM group.
I chose to install the OpenSSH server.

When I finished installing, the content of the USB flash drive had changed. A compare with the original ISO file found differences.

Update 1

I was able to install Ubuntu with a desktop graphical support on the 2007 iMac by using the mini.iso file. This was accomplished by using the dd command to copy the mini.iso file to the internal drive (/dev/sda). Next, boot to the Mac Startup Manager and select the Windows label under the internal drive icon. Once the Ubuntu installer starts, you can overwrite the the contents of the internal drive with the new Ubuntu installation.

Below are the exact steps, I used to place the contents of the mini.iso file onto the internal drive of the 2007 iMac. This is by no means the only way to accomplish this.

You will need a linux installer that offers a Command Line Interface (CLI). I chose the Debian firmware-10.7.0-amd64-DVD-1.iso file.
Transfer the file to a flash drive. I happened to have a 4 GB USB 2 flash drive and a 2011 iMac computer. By using the diskutil list command, I determined the identifier for the flash drive was disk1. The commands below were used to transfer the file to the flash drive.
```
diskutil unmountdisk disk1
dd if=~/Downloads/firmware-10.7.0-amd64-DVD-1.iso of=/dev/rdisk1 bs=1m
```
Download the mini.iso file.
Transfer the mini.iso file to the flash drive. The output from the ls -l ~/Downloads/mini.iso ~/Downloads/firmware-10.7.0-amd64-DVD-1.iso command is shown below. From the output, one can compute the mini.iso and firmware-10.7.0-amd64-DVD-1.iso files are 76 MiB and 3,772.3125 MiB long, respectively. (1 MiB = 1,048,576 bytes)
```
-rw-r--r--@ 1 davidanderson  staff  3955556352 Jan  5 16:10 /Users/davidanderson/Downloads/firmware-10.7.0-amd64-DVD-1.iso
-rw-r--r--@ 1 davidanderson  staff    79691776 Jan  5 16:07 /Users/davidanderson/Downloads/mini.iso
```
The output from the diskutil info disk1 | grep Size command is given below. From the output, one can compute the flash drive has a capacity of at least 3,853 MiB.
```
   Disk Size:                4.0 GB (4040748544 Bytes) (exactly 7892087 512-Byte-Units)
   Device Block Size:        512 Bytes
```
From the outputs shown above, I determined the command given below would copy the mini.iso file contents to a location above the contents of the firmware-10.7.0-amd64-DVD-1.iso file. (Note: 1m is 1 MiB = 1,048,576 bytes)
```
dd if=~/Downloads/mini.iso of=/dev/rdisk1 bs=1m seek=3773
```
Enter the command given below to eject the flash drive. Remove the flash drive.
```
diskutil eject disk1
```
Insert the flash drive in a USB port of the 2010 Mac. Start or restart the Mac and immediately hold down the option key until the Mac Startup Manager icons appear. Choose the external drive icon with the label EFI Boot. When the image below appears, pick Advanced options ..., then select ... Rescue mode.

Continue until a similar image to the one below appears. Pick Do not use a root file system, then select Execute a Shell in the installer environment and finally, <Continue>.

At this point, you should be able to enter commands.
Enter the command given below to transfer the contents of the mini.iso file to the internal drive. (Note: 1M is 1 MiB = 1,048,576 bytes)
```
dd if=/dev/sdb of=/dev/sda bs=1M count=76 skip=3773
```
Enter the command given below, then turn off the Mac and remove the flash drive.
```
exit
```

Update 2: Installing Ubuntu Server 20.04.1 LTS

I did use the Debian firmware-10.7.0-amd64-DVD-1.iso file to test if the mini.iso file would boot from the internal drive. However, IMO this is not a good method for installing the Ubuntu Server 20.04.1 LTS, for the following reasons.

The software need to install Ubuntu Server 18.04.5 LTS takes a long time to downoad.
The Ubuntu Server 18.04.5 LTS release is installed instead of the Debian Server 20.04.1 LTS.
Upgrading to the Ubuntu Server 20.04.1 LTS take a long time to complete.

I would recommend installing the Ubuntu Server 20.04.1 LTS by using a method similar to this answer. Some of the differences are given below.

You will be installing ubuntu-20.04.1-legacy-server-amd64.iso, instead of firmware-10.7.0-amd64-DVD-1.iso.
You will need to substitute vmlinuz and initrd.gz for the ones used in the linked answer..
Since up have a 64 bit EFI, you need to use firmware-10.7.0-amd64-DVD-1.iso file instead of firmware-10.7.0-i386-DVD-1.iso file.

I tested installation by using a 2007 iMac. When first booting to Ubuntu Server 20.04.1 LTS, a login prompt did not appear on the builtin display. This problem was solved by appending the following line to the /etc/default/grub file.

GRUB_GFXPAYLOAD_LINUX=text

Note: You will have to boot Ubuntu from recovery mode in order to login. Or, you can use ssh from another computer to login.

After appending the line, the command below needs to be executed.

sudo update-grub

The installer was unable to provide the software for the Broadcom wireless hardware. The problem was solved by executing the command give below.

sudo apt-get install firmware-b43-installer

Using the ubuntu-20.04.1-legacy-server-amd64.iso file, to install Ubuntu server on your Mac, is beyond the scope of your question. In other words, your question asked about the mini.iso file. If you want a more detailed answer with respect to using the ubuntu-20.04.1-legacy-server-amd64.isofile, then I suggest posting a new question.

References

Linux Wireless
b43 and b43legacy
GRUB/Tips and tricks: Disable framebuffer
Ubuntu Installation Guide
GNU GRUB Manual 2.04: 6.1 Simple configuration handling

Thank you for conducting these tests. It sounds like you might have some QA experience. Your results confirm a few rumours and my suspicions about how the issue that I am having is due to the GPU of the Mid-2010 iMacs not supporting Ubuntu. You were able to install Ubuntu and Ubuntu Server on 2 iMacs of a similar age to mine, one older and one younger, whereas I am not able to install any version of Ubuntu as the screen blacks out early on in the installation process. I have experience of installing Linux distros on a few computers so I feel confident that this issue is not caused by me. — Ambassador Kosh, Dec 26 '20 at 13:15
I appreciate the time and effort that you put into your answer it has saved me probably a lot more time and effort than it took you (I don't have enough reputation to vote on your answer being useful). By the sounds of things you are familiar with the history of iMacs and their compatibility with a variety of OS'. I think that I am going to setup a Linode account until I can find a computer suitable for this project. — Ambassador Kosh, Dec 26 '20 at 13:19
I would disagree with your conclusion that you can not install some version Ubuntu with or without a graphical desktop on your Mac. The problem probably is either you do not have the correct driver or you are not installing to BIOS boot. You probably need to either BIOS boot the installer from a DVD or from the internal drive. — David Anderson, Dec 26 '20 at 15:13
I am glad that you replied. In that case I will start exploring BIOS boot. Thanks again. — Ambassador Kosh, Dec 26 '20 at 20:26
FYI: I did install Ubuntu Server with desktop graphical support on the 2007 iMac. I used the mini.iso file that you suggested. Ubuntu BIOS boots using the modern GPT instead of a legacy MBR partition table. I would encourage you to try this. The version installed was Ubuntu 18.04.5 LTS. I am current upgrading to the current version. If a 2007 iMac can run Ubuntu Server, then I do not see why a 2010 iMac would not be able to. — David Anderson, Dec 26 '20 at 22:16
The upgrade to Ubuntu 20.04.1 LTS completed without any problems. (Posted this comment from the 2007 iMac running Ubuntu.) Connecting remotely through VNC to another Mac works well. I think the free RealVNC viewer works better than the Mac builtin viewer. So far, RDP has not worked properly. — David Anderson, Dec 27 '20 at 13:51
Hi Dave, Apologies for the delayed reply I haven't had any success until today when I managed to install Ubuntu Desktop 20.04 from a USB - Kubuntu Startup Disk Creator + the standard ISO file and then choosing the 'Install Ubuntu (safe graphics)' option. However, it is still not booting successfully. When I rebooted the computer after the installation was successful and then removed the USB when prompted, the computer displays the following message before turning the screen black: — Ambassador Kosh, Jan 05 '21 at 20:33
"Failed to set MokListRT: Invalid Parameter. Could not create MokListRT: Invalid Parameter. Importing MOK states has failed: import_mok_states failed() invalid parameters. Continuing boot since secure mode is disabled." Startup Manager did not recognise the USB if mini.iso was on it, irregardless of whether I used terminal commands or Startup Disk Creator, which just confirms your statement. When I tried to install the ubuntu-server or ubuntu-desktop iso files from USB the computer displayed "error No ums support in radeon module". Are these errors that you are familiar with? — Ambassador Kosh, Jan 05 '21 at 20:39
Congratulations on installing mini.iso on your 2007 imac. How did you connect to the internal drive of your old imac? That is an interesting approach. — Ambassador Kosh, Jan 05 '21 at 20:50
What do you mean by "How did you connect to the internal drive of your old imac?". The internal drive is inside the iMac behind the screen. There is a SATA cable connected between the HDD and the logic board. — David Anderson, Jan 05 '21 at 20:56
Ah I interpreted your Update as you connecting your old iMac to another machine and running commands on this 2nd machine. I think that I assumed that you did this because the 2010 iMac in question is not capable of booting successfully at all. — Ambassador Kosh, Jan 05 '21 at 21:00
When you EFI boot, the Mac is booting from /EFI/BOOT/BOOTX64.EFI file in the /dev/disk0s1 EFI partition. This is the same as the /EFI/ubuntu/shimx64.efi file. This is why you are getting MOK error messages. You could try booting grub instead. This would be the /EFI/ubuntu/grubx64.efi file. See here. Personally, I would avoid all of this by BIOS booting. — David Anderson, Jan 05 '21 at 21:09
I updated my answer to include the method I used to transfer the mini.iso file to the flash drive. If you need the commands translated to a different operating system, let me know. — David Anderson, Jan 05 '21 at 23:47
Thank you for your suggestion and the accompanying instructions. I followed them though my end result is not the same as yours. So now, when I boot to Startup Manager it doesn't list any drives to boot from, just the drop down box where I can choose the wifi connection. If I plug in a USB drive it will recognise that. If a USB drive isn't plugged in and I leave it on Startup Manager for a while it automatically goes into Internet Recovery mode. — Ambassador Kosh, Jan 18 '21 at 14:31
I explained how I tested the mini.iso file on a 2007 iMac. I am what went wrong when you tried to follow my instructions. Using the dd command to copy files is prone to failure if a mistake is made in the math. Anyway, I updated my answer with how I think you should install Ubuntu Server. — David Anderson, Jan 22 '21 at 12:42

Why isn't Startup Manager showing Ubuntu Netboot USB - mid 2010 imac 21.5"

1 Answers1

Update 1

Update 2: Installing Ubuntu Server 20.04.1 LTS

References