MP 1,1-5,1 Booting 5,1 from usb to FreeDOS?

[toke lahti]

Is this possible?
If it is, how?

I'm wondering if there are somewhere specced the needs for usb drive to boot 5,1.
What it needs to appear in Boot options screens?

Apple AHT is GUID, is that needed?
Can MBR usb stick also appear there?
Just tested with Mavericks install usb, which was made with Apple's official method.
Does not show up... EDIT: Does show up. 5,1 didn't like the µSD-card adapter...

What does the mac actually looks from usb stick, when it is deciding if it can boot from it?

 

[Macschrauber]

a Mac Pro 1,1 to 5,1 does not boot a MBR partitioned volume via USB.

DD the image to an old spinner and boot it on a Sata port. 2nd DVD port is ok also.

 

[toke lahti]

a Mac Pro 1,1 to 5,1 does not boot a MBR partitioned volume via USB.

DD the image to an old spinner and boot it on a Sata port. 2nd DVD port is ok also.

I chose to use usb stick with Elementary OS. I guess it has a gpt.
Flashing the gpu went fine, once I learned where to run amdflash from and how to give it the needed priviledges.

I guess freeDOS can't be booted from gpt, so only option to use it with cMP is really with shiny disc?

 

[Macschrauber]

I chose to use usb stick with Elementary OS. I guess it has a gpt.
Flashing the gpu went fine, once I learned where to run amdflash from and how to give it the needed priviledges.

I guess freeDOS can't be booted from gpt, so only option to use it with cMP is really with shiny disc?

See the 2nd sentence of https://forums.macrumors.com/threads/booting-5-1-from-usb-to-freedos.2398908/post-32389114

Edit: maybe you dont know the term spinner for a hard drive.

 

[MacNB2]

I chose to use usb stick with Elementary OS. I guess it has a gpt.
Flashing the gpu went fine, once I learned where to run amdflash from and how to give it the needed priviledges.

I guess freeDOS can't be booted from gpt, so only option to use it with cMP is really with shiny disc?

If you wanted to Flash your AMD Gpu and are booting, via OpenCore, then you can drop into OpenCore's UEFI Shell and run amdvbflash.efi from that shell. I posted it here and also gave a brief overview of how to enable & use here it.

 

[Dayo]

Is this possible?
If it is, how?

Purely in terms of booting stuff like FreeDOS from USB, as mentioned earlier, cMP does not load legacy bootcode on external disks such as USB sticks.

Note however, that FreeDOS only creates the legacy bootcode setup AFTER running the installer on the distributed LiveCD but the distributed LiveCD, like most Linux type distributions, can be used to run FreeDOS in a "Test Mode" directly.

So, what you can do is to create a Ventoy setup on a USB stick:

Ventoy

Ventoy is an open source tool to create bootable USB drive for ISO files. With ventoy, you don't need to format the disk again and again, you just need to copy the iso file to the USB drive and boot it.

www.ventoy.net

Then, copy the FreeDOS iso file into Ventoy, reboot and load Ventoy.
Once loaded, use this to run the iso file (which will be listed as an option along with any other iso files in Ventoy).

I have only used Ventoy with RefindPlus so far but cMP should be able to run it directly and OpenCore should also load it.

I have Ventoy on a crappy USB stick and it loads slowly. I found selecting the "Grub2" option within Ventoy most reliable. I think the "Boot Normally" option might be trying to use legacy bootcode (Ventoy uses a custom HybridMBR setup) which as said, does not work for external disks on cMP.

You will ordinarily not be able to save stuff for subsequent sessions in "Test Mode" but Ventoy has a "Persistent Option" to enable this. You will need to refer to the project docs on how to set this up.