Photoshop graphics work fine on host , but not in VM

On my host iMac I can use graphics hardware acceleration, and all Photoshop CS6's functions are available - e.g. lighting effects rendering. I also have CS6 in the VM on the same iMac running OS X Snow Leopard Server but it does not detect what graphics card I have (in Photoshop Preferences) and tells me that graphics hardware acceleration is not available, and I therefore cannot use all Photoshop's features.

Why is the VM not detecting and using my graphics card, yet the VM has no problem playing videos in my browsers?

Technical details:

• Core i7 iMac (2011), 16GB RAM, Fusion drive (SSD+HD), Graphics AMD Radeon HD 6770M 512 MB, running MacOS 10.9.5 (MY PREFERRED CHOICE)
• Parallels Desktop 10.4 running Guest Server MacOS 10.6.8 - please do not recommend I upgrade Parallels; this is the CORRECT version for both host and guest OS.

Please note - this is not a Photoshop problem; on the host, under Preferences / Performance it has detected my GFX, but the same software on the VM is blank where there should be a listing of it.

 

Guest VM's in Parallels ( or other desktop Mac virtualisation tools ) do not access your host hardware directly, they present a virtual GFX adapter to the guest OS. As such they're not able to provide access to libraries such as Metal to software running within the guest OS.

This feature is usually referred to as VT-d or Hardware Passthru and is only available on higher-end bare-metal virtualisation tools such as Hyper-V or ESXi ... I think VMWare Workstation for Windows also has this capability but I've not used it for a while so can't be sure. It also needs to be supported in the device BIOS and on the CPU to work, I'm not sure if Apple provide support for this within their firmware.

Even if Parallels could support this feature, it's very likely that Snow Leopard wouldn't have working video drivers for your iMacs modern graphics card... so what you're trying probably wouldn't work anyway.

 

Thanks for your reply Dave. In one aspect I can correct you - I did have Photoshop CS6 running perfectly capably on a Mac of this age in Snow Leopard (both this and my previous Mac are 2011 models and ran both Snow Leopard and Mavericks and Snow Leopard Server in a Parallels VM).

What I'm rather confused by is where you say guest VMs cannot access my host hardware directly. If that's the case, how does it read my USB drives and CDs without problem?

 

Using a virtualised USB adapter which passes commands through to your real USB adapter...in the same way the display output is connected to a virtual video card.

 

Ok. Now I guess I'm coming full circle here ... if the 'virtual hardware' can play videos, do most of the stuff Photoshop has to offer, read my USB drives and DVD/CDs, play audio, pretty much everything my host Mac can - why can't it render lighting effects in Photoshop?

 

It would seem the answer may be in this topic:
https://forum.parallels.com/threads/failure-to-recognize-vram-and-quartz-extreme.342936/
Am I right?