[matthewfcarlson]

I have been bothering the VM team for years for VM GPU pass through. I worked on the Apple Silicon Mac Pro and it would have made way more sense if you could run a linux VM and pass through the GPU that goes inside the case!

Sadly, as you can tell, they have not taken me up on my requests. Awesome that other people got it working!

[m132]

It looks like the pass through part here was implemented using standard DriverKit interfaces, if I'm not mistaken. That is, the PCIe BAR can already be mapped from the user-space, without any extra modifications to macOS. It's just a matter of VMMs, such as QEMU, adopting this interface in addition to Linux VFIO and the like (unless you're talking about Virtualization.framework, which is kind of a VMM of its own).

What exactly do you feel macOS is missing?

[anp]

I’m not very familiar with the specifics of pass through but IIUC only being able to map 1.5gb of active DMA buffers at a time is pretty limiting.

[monocasa]

Isn't driverkit essentially a separate user space stack compared to regular code? I remember seeing the driverkit specific dyld caches in macos root partition images that included their own copies of everything down to libsystem. Getting driverkit code to run in the same process as normal user code seems like it'd be quite an uphill battle.

Presumably with the right entitlements you can just hit the same (presumably IOKit) syscalls that driverkit does. But that's an extra layer of reverse engineering, and you're not really using driverkit anymore.

[scottjg]

it is a separate stack, but that probably doesn't matter much. a user process (in my case, qemu) can communicate with a driverkit driver. the user process can also map memory through the driver, which is how this pci passthrough system works.

i don't think the issues with the project really are specific to driverkit.

[mikae1]

>> This project requires a special entitlement from Apple. I’ve requested it, and heard they may be open to granting it, but I have not yet heard back, and I’m told that the wait time could be months.

> I have been bothering the VM team for years for VM GPU pass through.

Good luck. I'm sure they're keen on giving people access to this so that people can spend their money on NVIDIA GPUs instead of buying more expensive Macs. :)

Would of course be awesome, but I'd be very surprised if it happened.

[codebje]

There isn't a more expensive Mac option to buy if what you're after is a gaming GPU. It's more likely that the VM team sees this as a very low benefit ticket to pursue given the tiny segment of Mac gamers hoping to improve their options with a Linux VM for gaming.

(Meanwhile, I'm recompiling Wine to see if I can patch it to address an issue that was hotfixed in Proton two weeks ago but isn't in a CrossOver build yet, so yeah, there's maybe some arguments to be made here that I'd be a potential beneficiary. If I weren't too cheap to spring for an eGPU in today's market, anyway.)

[m132]

The entitlement in question is the standard `com.apple.developer.driverkit.transport.pci` [0], required for anything that touches the PCIe bus [1]. Apple is generally restrictive with how much third-party applications can do on machines with SIP/"full security", so I'm not exactly surprised. It's not an Apple-private entitlement, however.

The VFIO-style driver made by the author of this also appears generic enough to support all kinds of PCIe, not just GPUs. Apple might find a way to weasel out of this ("hey, this is for hardware companies and you don't seem to be affiliated with one", "your driver requests too broad access", etc.) if there really is a conflict of interest, but so far, there's a chance it will just get rubber-stamped.

I can see them rejecting it for legitimate reasons, though, at least as far as "legitimate" with Apple goes. This driver is essentially a thin layer over PCIDriverKit, exposing all functionality that's supposed to be behind the entitlement to arbitrary applications, in similar fashion to WinRing0. They probably didn't come up with all this bureaucracy only to sign something like that in the end. We'll see what happens.

[0] https://github.com/scottjg/qemu-vfio-apple/blob/84ecdcf5db6b...

[1] https://developer.apple.com/documentation/pcidriverkit/creat...

[scottjg]

two semi interesting things to note around this:

1. Virtualization.framework seems to support some form of GPU passthrough from the host (granted, not eGPU - it's for the integrated GPU). I think the primary use case is having macOS guests get acceleration, while still sharing GPU time with the host. There is also a patch that recently hit QEMU mainline that supports using the "venus server" with virtio-gpu to support a similar functionality for Linux guests under Hypervisor.framework.

2. Apple internally has some kind of PCI Passthrough support available in Virtualization.framework. It seems like the code is shipped to customers in the framework, but it relies on some kind of kext or kernel component that isn't shipped in retail macOS. I can't say if that's intended to ever be released to customers, but clearly someone at Apple has thought about this the feature.

[m132]

I experimented with booting Arm macOS 14-26 in QEMU a while back, building on the work of Alexander Graf for macOS 12-13, and reverse-engineered substantial parts of Hypervisor.framework, the in-kernel hypervisor, and a bit of Virtualization.framework. Got newer versions of Sequoia to boot past the log in screen, with GPU acceleration too.

Unless there's another method I missed, the internal GPU "pass through" of Virtualization.framework you're thinking of might actually just be paravirualization, at least that's what the name suggests. It's implemented in the public ParavirtualizedGraphics framework [0], albeit for PG on Arm macOS, the relevant interfaces are private [1]. I haven't looked that deep into it per se, but, fixing the bugs around it, I've run into a few clues suggesting that it's just a command stream + shared memory being passed around. It also uses its own generic driver on the guest side.

Great job, by the way! Love how authors of pieces like this casually come here to comment :)

[0] https://developer.apple.com/documentation/paravirtualizedgra...

[1] https://github.com/qemu/qemu/blob/edcc429e9e41a8e0e415dcdab6...

[my123]

FYI: https://patchew.org/QEMU/20260324204855.29759-1-mohamed@unpr...

There's some randomness around Tahoe for FileVault and it crashing because Data is detected as not encrypted (and that's not OK on bare metal). If hitting that case you might need to enable FileVault inside the VM (and remember to sync aux storage afterwards if not done)

[m132]

Looks like someone beat me to it! Thanks!

I see the author of this patch set has run into a few similar issues as me. Strangely, not all of them: I don't see patches for the new PCI MSI-X device introduced somewhere in Sequoia (IIRC), a source of kernel panics for me; and there's still a bug in the PG MMIO path that casts all writes to 32-bit, this one caused me a lot of headaches (no errors but no video adapter detected). I'm somewhat surprised to hear that this works!

There's two significant problems that we both have came across:

- LLVM now favoring pre-indexed load/stores which trap with ISV=0 for MMIO accesses, and those ending up in the GIC initialization path of the newer macOS kernels (looks like there's a separate patch set for this [0]),

- Hypervisor.framework trapping PAC HVC calls.

It seems like the latter has been worked around here by signing QEMU with an Apple-private entitlement and running with SIP off, but there's actually a different way! While some HVCs are trapped right in the host kernel, the PAC trapping happens within Hypervisor.framework itself (at least in the host OSes I tested). It's possible to patch out this functionality without special privileges or talk to the in-kernel hypervisor directly. I originally tested with the former, and chose to implement the latter as a separate accel in the code I was planning to submit upstream, but the complexity of it exploded and, besides confirming that it would have worked, I haven't managed to finish my implementation.

Does the Tahoe crash you mentioned manifest itself in stage 2 iBoot panics? I must admit 26 was never quite my priority so I haven't looked into it, but if so, it might have been closer to booting than I thought :)

[0] https://lists.nongnu.org/archive/html/qemu-devel/2026-04/msg...

[my123]

It was a kernel panic for Tahoe. Anything between macOS 12 and 26 wasn't tested so releases in-between might have more issues.

The userspace reboot after FileVault password entry acts a bit oddly with QEMU input devices so you might need to attach a new USB tablet or kbd from the monitor.

> looks like there's a separate patch set for this

Yup and it's a bit of a problem to figure out the right thing to do for it on the upstreaming side as normal guests aren't supposed to do that.

> It's possible to patch out this functionality without special privileges or talk to the in-kernel hypervisor directly

Or pre-patch them all to HVC #1 works too. Patching the host Hypervisor.framework sounds quite brittle especially after they moved to a pile of C++

[m132]

> It was a kernel panic for Tahoe.

Ah, must be something else then.

> normal guests aren't supposed to do that

Oh how I wish Arm didn't let anything like this slip into the architecture spec to begin with! Massive source of pain, especially with protected memory/CCA guests. It's not macOS triggering this in isolation either. Most start up binaries for QNX do this too, somehow also in the GIC init path.

I've looked at how different hypervisors/VMMs handle this and, if this makes that patch set any less hacky, Virtualization.framework, QNX Hypervisor, and (I think) VMware all decode and emulate those instructions in software. Virtualization.framework is a remarkable spaghetti in this regard :)

> Or pre-patch them all to HVC #1 works too. Patching the host Hypervisor.framework sounds quite brittle especially after they moved to a pile of C++

Possibly! IIRC, if HCR_EL2.HCD==1, HVC should trap as undefined instruction. Not sure how much of HCR_EL2 can be set from the user-space, but perhaps this could be the least invasive way.

Simply ignoring the instruction, though, is not enough. I remember in my setup, with HVC handling stubbed out, secondary cores would always fail to start. I suspect this to be the culprit.

The SMP bring-up code would fail to pass pointer authentication on the first indirect branch. It would then immediately pivot into FLEH->SLEH->panic(). panic() shortly would attempt to make an indirect jump itself, hoping to crash the other processors, but instead, getting stuck in a loop of calling itself. This would eventually get caught by a stack overflow guard somewhere in FLEH/SLEH, which would place the core in an infinite loop, and... the system would continue to run with just the boot core. Yo dawg, I heard you like panics :)

[scottjg]

thanks!

there also appears to be a generic pci passthrough path. we were discussing it on the qemu-devel list: https://lore.kernel.org/qemu-devel/C35B5E97-73F2-4A60-951B-B...

[m132]

Oh, thanks for letting me know, and for the upstreaming work too! I might join the party once I find some more time :)

[brcmthrowaway]

I still believe the lack of NVIDIA GPU support in the Mac Pro will go down as one of the greatest missed opportunities in tech.

Anyway, the Mac Pro is dead now. There's only so much sales audio and video professionals can provide.

[runjake]

There was some bad history between Apple and Nvidia. Perhaps with a new generation of leadership at Apple things might change.

https://www.reddit.com/r/hardware/comments/1hmgmuf/apples_hi...

[mercutio2]

I wasn't in the room when it happened, but this is very different than the story told internally about why Apple became allergic to Nvidia.

Arguably more petty. SJ has been dead for almost 15 year now, I imagine the C-suite might get over it at some point.

[burnte]

> I imagine the C-suite might get over it at some point.

Not at Apple. They have a looooooong institutional memory that's passed down. They're still pissed at Gizmodo. I'm shocked they made a deal with Intel. I think if it hadn't been for the global political uncertainty right now they would not have signed that fab deal with Intel.

[kalleboo]

> Arguably more petty

I can believe it. IIRC Jobs also snubbed ATI once after they leaked the GPUs going in the next PowerMac model.

[runjake]

Do tell. Or at least provide hints?

[firecall]

Maybe with Tim and Jensen going on holiday together in China, the relationship might be healed somewhat.

Things have moved on since the days where GPUs in Macs were a priority.

But then the AI race has changed things. So who knows - maybe we will one day see official eGPU support from Apple and new drivers from nVidia. Wouldn't put on money on it though....

[Aurornis]

> I still believe the lack of NVIDIA GPU support in the Mac Pro will go down as one of the greatest missed opportunities in tech.

I don’t know about that. Apple supported some full size GPUs in past product lines and the number of users was very small. Granted, LLMs change that demand but the audience for Mac Pro buyers who would use a full-size GPU that is impossible to obtain is almost nothing compared to their laptop sales.

[bigyabai]

The audience for Mac Pro buyers is almost nothing, full stop. It failed to find a niche, and now Apple is getting rid of it: https://www.macrumors.com/2026/03/26/apple-discontinues-mac-...

Part of the reason the new Mac Pro failed to find an audience can definitely be blamed on macOS' hostility to third party hardware. Who knows what Apple would be worth if they beat Nvidia's Grace CPU to the datacenter market. It was certainly their opportunity.

[pjmlp]

Yes, because they already moved on to workstations powered by either Windows or Red-Hat Linux/Ubuntu.

The only ones left were people like John Siracusa that still hoped to the very last minute, that Apple would change their mind.

[brcmthrowaway]

True, they could do any number of things. But a datacenter play would appear quite random to investors and their core audience. Broadcom + Nvidia however...

[trollbridge]

Apple seems to be content to sell shovels in the AI gold rush.

Admittedly… what’s on my desk? A MacBook M4 Air, a Mac Studio, and there’s an x86 iMac in the corner.

What goes in the travel bag? A MacBook Pro or the Air.

Every time I look at buying something else the math doesn’t add up.

The 5090 sits in a commodity PC chassis. It’s not like I need a model running on my own computer.

[pjmlp]

The missed opportunity is like with server market, now giving the workstation market to Windows and Linux.

It isn't only audio and video.

[jbverschoor]

I guess that little problem with the Nvidia chips overheating in the MacBook Pro didn’t give Apple a lot of confidence

[bigyabai]

The Mac Pro isn't a Macbook Pro. It has socketed PCI slots and should be able to support the user's hardware in macOS' software, regardless of how Apple feels.

[xp84]

Seriously, the decades-long grudge against Nvidia that we always hear about seems like the most ridiculous and immature business move. I expect that kind of thing from an individual, you know, “I NEVER fly American Airlines!!!” but in business, such a permanent ban on one of the two players in a market, the leader no less. I don’t get it.

Maybe it doesn’t matter that much now because they’ve literally exited all the businesses where an external GPU is going to matter. But sticking with AMD all that time out of spite is just wild.

[Melatonic]

Audio and Video professionals jumped ship around the time Apple canned all the pro software

[caycep]

What are the chances there will be another Mac Pro in the future?

Will Apple ever make a computer that makes Siracusa happy? (and do you have the "Believe" shirt?)

[pjmlp]

Never, a couple of years ago Apple gave up on the server market, that is why having Swift on Linux is so relevant for app developers.

Now they gave up on the workstation market that really enjoys their slots for all myriad of cards.

Having a thunderbolt cable salad is only for those that miss external extensions from 8 and 16 bit home computer days.

Which is clearly what Apple is nowadays focused, if you look back at the vertical integrations before the PC clones market took off.

So now if you really need a workstation, it is either Windows, or one of those systems sold with Red-Hat Enterprise/Ubuntu from IBM, Dell , HP.

[hedora]

If you want a workstation, you are probably better off building it yourself, or having your local computer store do it. The primary exceptions are AMD strix halos or the nvidia dgx spark.

I haven’t seen a non-laughable workstation config from the big vendors since the dot com bubble. Presumably they exist, I guess?

[binarycrusader]

DISCLAIMER: Only speaking for myself, not employers or affiliates.

I've been pretty darn happy with the Puget Systems custom workstation I ordered last year before the memory craze started (especially since it has 192GiB of DDR5).

I also ordered another family member a custom "Tiki" system from Falcon Northwest and that has also been quite excellent from what I've seen and they've told me.

Now is obviously not the most economical time to order a new system, but when it is appropriate (and for what it's worth) I think those are two great system builders.

[hedora]

I wouldn’t count them as a big vendor, but I’ve only heard good things. Local shops around here charge like $99 to put a machine together, install an OS and run burn in testing. You get more choice than an outfit like puget, but less carefully tested part / cooling selection, etc.

The last I checked, the really big players tended to add value add gimmicks (water cooling is a common one, custom psu form factors are another) with reliability / compatibility issues. That’s the tier to avoid, not the Puget systems of the world.

[binarycrusader]

I picked both Puget Systems and Falcon Northwest because for the most part, both focus on pre-tested off-the-shelf parts with good reliability data from their own servicing.

My Puget Systems workstation for example has a simple AIO for cooling with some Noctua fans and a Fractal Design 7 XL full tower case.

The Tiki system I ordered for a family member from Falcon Northwest does have a custom case, but almost everything else is fairly standard inside. The super small form factor was important to them.

Could I have built either of these systems myself? Absolutely -- I've done that for at least prior 20 years or so, and I've built dozens for employers, but it sure was nice to buy one that just worked this time instead of having to having to fiddle with memory sticks or find exactly the right bios settings for stability, etc.

I'm well aware of the premium I paid but I can honestly say it has been incredibly nice to have a workstation that just works without having to fiddle with bios updates or hardware. I also don't really have the time to spare so I was entirely willing to trade funds for time.

[fluoridation]

Non-standard parts are not about value-adding, they're about cost-cutting if you're feeling charitable, and about forcing vendor lock-in if you're not.

[pjmlp]

Yes they exist, and business aren't building PCs from parts themselves.

[fragmede]

Just because you're cheap and don't value your time, doesn't mean they don't exist.

[esseph]

They get features that us plebs buying retail don't get, at prices the vast majority of us wouldn't pay if it were our own cash.

[dwaite]

IMHO - extremely little.

It is too inefficient to design a machine which _might_ have two GPU and a flock of additional drives installed into it. It just makes sense to instead design around having independent hardware in its own case, which can meet its own power/cooling needs. This has been a design goal since the trashcan Mac.

Having a PCIe bus increases bandwidth and reduces latency, but once you account for eGPU and for people who would be happy building custom solutions on platforms other than macOS, there's likely not enough identified market for a modular design.

[crdrost]

It feels like half the problem in this blog post is dealing with memory access issues induced by QEMU and the VM boundary... it's probably something dumb I'm missing, but if you boot up Ubuntu in Docker, wouldn't the NVIDIA drivers still load? And then you wouldn't have to fight Apple about the memory management because OSX would still own the memory?

[swiftcoder]

> but if you boot up Ubuntu in Docker, wouldn't the NVIDIA drivers still load?

Even if the drivers loaded, they can't talk to the GPU from within docker (unless one implements PCI passthrough). MacOS owns the PCI bus in this scenario.

[smw]

docker on macos runs in a linux vm

[jmalicki]

The driver wants to own the memory is the problem.

[SilentM68]

In your view why have they refused to implement a "Linux VM and pass through the GPU that goes inside the case?"