MP 7,1 Cannot install from bootable Mojave Installer?

[arjunchawda]

Hey,

I’m trying to downgrade my Mac Pro 7,1 from Catalina to Mojave.

I have downloaded and created a bootable USB installer for 10.14.6. However, when I boot up the Mac Pro 7,1 from the installer USB, I get the prohibited sign on my display.

(I’ve disabled secure boot from recovery options, and I’ve also allowed booting from external or removable media)

(This USB installer I’ve created definitely works fine when plugging it in to my MacBook Pro and booting from it)

Any ideas on why this may be?

 

[MacUser2525]

An earlier macOS will never install on a machine that shipped with a later version, there is no support for the machine in the installer for it. You are stuck with Catalina or later for the OS on that machine.

 

[DearthnVader]

An earlier macOS will never install on a machine that shipped with a later version, there is no support for the machine in the installer for it. You are stuck with Catalina or later for the OS on that machine.

I mean, sometimes you can get older OS's than what shipped with your Mac to work.

We have OS 9 on the G4 Mini;-)

It's just "what is the point of it?".

If you have something like a 32bit apps that won't work on Catlina, then maybe it's worth the hack........
[automerge]1577550079[/automerge]

Hey,

I’m trying to downgrade my Mac Pro 7,1 from Catalina to Mojave.

I have downloaded and created a bootable USB installer for 10.14.6. However, when I boot up the Mac Pro 7,1 from the installer USB, I get the prohibited sign on my display.

(I’ve disabled secure boot from recovery options, and I’ve also allowed booting from external or removable media)

(This USB installer I’ve created definitely works fine when plugging it in to my MacBook Pro and booting from it)

Any ideas on why this may be?

The first step is to disable SIP, then:

sudo nvram boot-args="-no_compat_check -v"

 

[maflynn]

I mean, sometimes you can get older OS's than what shipped

Yes when there was a minor spec bump, the Macpro has all new components that Mojave does not have, there's simply no kexts and there's no support in legacy operating systems

 

[h9826790]

I tried 7,1 SMBIOS in Mojave on my 5,1.

It can boot, it can work, but apparently all functions that depends on the board ID won’t work (natively).

So, IMO, no point to downgrade a 7,1 to Mojave (regardless can be done or not).

 

[Snow Tiger]

It's an old rule you cannot install a macOS ( or Mac OS X ) onto a Mac that predates the OS installed at the factory . That said , maybe if you really like a certain OS version you could run it in a VM ?

 

[arjunchawda]

No problem!

I just had to bite the bullet and find updates for all the audio plugins I use.

 

[DearthnVader]

It's an old rule you cannot install a macOS ( or Mac OS X ) onto a Mac that predates the OS installed at the factory . That said , maybe if you really like a certain OS version you could run it in a VM ?

This just isn't true, you can install 10.2.x on some Mac's that shipped with 10.3.x.

I have no doubt that 10.14.x could be made to work on the 7,1, to some degree, it's just a matter of how worthwhile it is, and the trade off between all the things that won't work well.

The macOS is pretty modular, and will run on a wide verity of "unsupported" hardware, just ask a Hackintosher.

 

[MacUser2525]

The macOS is pretty modular, and will run on a wide verity of "unsupported" hardware, just ask a Hackintosher.

Those actually have the hardware features needed, just not the efi firmware. That can be faked by the bootloader and they still need the .kext to run the hardware. A machine that has no .kext for the hardware in it will never run the OS that requires it.

 

[DearthnVader]

Those actually have the hardware features needed, just not the efi firmware. That can be faked by the bootloader and they still need the .kext to run the hardware. A machine that has no .kext for the hardware in it will never run the OS that requires it.

Verbiage problems.........

Words like never are tricky words.

It will likely never be supported to run an Mac OS/macOS earlier than the version your Mac shipped with, that doesn't mean it can't be done.

It's a matter of how worthwhile it is to hack an older OS to run on it, how much time and effort people are willing to put into it, and how much talent you can draw to the project.

 

[Snow Tiger]

This just isn't true, you can install 10.2.x on some Mac's that shipped with 10.3.x.

But did that person use an officially released Mac OS X CD installer ? I'm certain a clever person can get an OS running on unsupported hardware .

 

[DearthnVader]

But did that person use an officially released Mac OS X DVD installer ? I'm certain a clever person can get an OS running on unsupported hardware .

10.2.x was pretty robust, the kernel didn't have the code to halt on unknown CPU's.

If you are certain it can be done, don't use blanket statements about how it can't be done.

Like I say, it's a matter of how much work people want to put into it.

Some of us do it, just because it's there, and people say it can't be done.

Tho this type of OS hacking is not really that productive, the OP didn't really describe the reasons for wanting to install Mojave on an unsupported model, but one would assume it's some sort of production environment, and it's understandable people would just tell him it can't be done, when really, it's likely better said that it shouldn't be done.

I'm not trying to be obtuse, but I sort of just that way naturally when people use the wrong words to spread information that isn't really true.

I think it's fair to say that, in this case, it isn't really worthwhile, unless someone or a large group of 7,1 owners, at some point, can offer some compelling need to do it.

 

[Snow Tiger]

10.2.x was pretty robust, the kernel didn't have the code to halt on unknown CPU's.

If you are certain it can be done, don't use blanket statements about how it can't be done.

Like I say, it's a matter of how much work people want to put into it.

Some of us do it, just because it's there, and people say it can't be done.

Tho this type of OS hacking is not really that productive, the OP didn't really describe the reasons for wanting to install Mojave on an unsupported model, but one would assume it's some sort of production environment, and it's understandable people would just tell him it can't be done, when really, it's likely better said that it shouldn't be done.

I'm not trying to be obtuse, but I sort of just that way naturally when people use the wrong words to spread information that isn't really true.

I think it's fair to say that, in this case, it isn't really worthwhile, unless someone or a large group of 7,1 owners, at some point, can offer some compelling need to do it.

You didn't answer my question .

I have a basement full of ancient Macs . I'm tempted now to hunt down one of my late production G4 MDDs that originally shipped with 10.3 and see if my official 10.2 installer disc will load Jaguar . I'm pretty certain I won't be permitted by Apple to do this .

 

[DearthnVader]

You didn't answer my question .

I have a basement full of ancient Macs . I'm tempted now to hunt down one of my late production G4 MDDs that originally shipped with 10.3 and see if my official 10.2 installer disc will load Jaguar . I'm pretty certain I won't be permitted by Apple to do this .

I don't know the answer to you question, because I never tried it, as I've never found a compelling reason to do it. I just know it has been done by someone here in the PPC section of the forum.

Mostly, if you don't mind doing a little Open Firmware hacking, you should be able to get the install CD to boot and install. Later versions of OS X that have the kernel that halts on unknown CPU's require a kernel patch to remove it, so booting from a official install CD would be problematic.

OS X's mach_kernel is wise to Open Firmware PVR hacks, tho OS 9 is none the wiser. Conversely OS 9 is wise to PCI register hacks, and OS X is none the wiser.

Mostly, OS X/macOS has a lot of abstraction, so it's generally easier to get it to run, once you get the kernel to load, it would likely run on a toaster.

 

[MisterAndrew]

Well, we know Apple was using Mojave on the 7,1 before it was released. The graphics drivers were present since 10.14.5. Of course they could have been using a build never released to the public.

 

[MacUser2525]

Verbiage problems.........

Words like never are tricky words.

It will likely never be supported to run an Mac OS/macOS earlier than the version your Mac shipped with, that doesn't mean it can't be done.

It's a matter of how worthwhile it is to hack an older OS to run on it, how much time and effort people are willing to put into it, and how much talent you can draw to the project.

Words are indeed tricky you choose yours like Apple does when dropping support for a machine that will partially run the OS, allowing that to happen. Your edge case does not apply here, like other models that have been released that required that special build they came with for the support of the chips on it. These are the same the drivers are not present for the earlier version of the OS so it will not work with it.

 

[DearthnVader]

Words are indeed tricky you choose yours like Apple does when dropping support for a machine that will partially run the OS, allowing that to happen. Your edge case does not apply here, like other models that have been released that required that special build they came with for the support of the chips on it. These are the same the drivers are not present for the earlier version of the OS so it will not work with it.

Here again, things that are misleading or just untrue.

The G4 Mini didn't support OS 9 until we made that true.

You're trying to set an artificial bar to only things that are supported by Apple. Some of us do all sorts of unsupported things with our computers and we reject you artificial bar.

The OP didn't ask if it was supported by Apple, if that's what he wanted, then the answer is no, it's not supported, not that it can't be made to work.

 

[MacUser2525]

Here again, things that are misleading or just untrue.

The G4 Mini didn't support OS 9 until we made that true.

You're trying to set an artificial bar to only things that are supported by Apple. Some of us do all sorts of unsupported things with our computers and we reject you artificial bar.

The OP didn't ask if it was supported by Apple, if that's what he wanted, then the answer is no, it's not supported, not that it can't be made to work.

Enough of you bye.