RAM limitation in EFI

[Toitoine]

I can't create VM with more than around 3,5 Go with EFI bios enabled

The VM starts with a black screen and does nothing.

[vasily Levchenko]

Could you please attach the log file ?

[Toitoine]

The log is full of this kind of message with various register number: Write to extended register 256 fallen back to generic code.

Since it is produced by DevPciIch9.cpp, I've changed the VM settings from ICH9 to PIIX3 and it works.

[voltagex]

I have the same issues - logs attatched

[angiest]

I'm having essentially the same problem. OSX host, EFI-enabled (Linux) guest. Booting into the UEFI shell and running memmap confirms that only ~3.5GB of RAM are being presented. My host is OSX 10.8.5, VBOX is 4.3.14.

[Frank Mehnert]

Partly fixed in VBox 4.3.20. The ICH9 problem is still not fixed but with PIIX3 it's possible to announce more than 3.5G to the guest.

[aeichner]

Works here with a recent VirtualBox release and ICH9, closing as fixed, please reopen if still relelvant.

[TylerLoch]

Unfortunately, this is still a problem with EFI guests as of VBox 5.1.4 with an ICH9 chipset configured.
Tested on both an Ubuntu 16.04 host and OS X 10.11.6 host.
Tested on both Ubuntu 16.04 guest and OS X 10.9.x guest.

As mentioned before by web007 in Ticket #7002:

From 2048MB up to 3488MB success and boots to the OS
From 3489MB to 3504MB the system fails and shows an EFI error "no mapping found"
From 3505MB and up, the system fails to boot and shows just a blank screen

I will attach a very simple storage-less VM that demonstrated the issue. If RAM is set above 3504MB, no image ever appears on VM "screen", and VM does not boot. If RAM set below this limit, EFI posts.

[TylerLoch]

Simplest possible test VM to demonstrate the issue. If RAM set above 3504MB, no image ever appears on VM "screen", and VM does not boot. If RAM set below this limit, EFI posts.

[Socratis]

@TylerLoch

I tried it on a 10.9.5 host, running VirtualBox 5.1.6, with 10.11.6, 10.9.5 and 10.6.8 guests. It works fine to all your limits and I even took it up to 6GB. It works. And I have been using it for a long time, way before the 5.0.x series. And now even the guests report it correctly, compared to before where there was a discrepancy (see https://www.virtualbox.org/ticket/13211#comment:2). I did not have an actual Ubuntu-64 VM with EFI to test.

On your 4GBTest although, it had the symptoms that you describe. No EFI splash screen.

[TylerLoch]

@socratis, in your tests, how much video memory did you have configured?

I've found that any amount of Video Memory configured over 64MB (even 65MB) will result in a fully working ICH9/EFI VM with any amount of RAM!

If you reconfigure my 4GBTest VM with 65MB of video memory or higher, you should see it post.

[Socratis]

I always give it the maximum 128 MB of video RAM, that's maybe why I didn't see the problem that you're reporting. I'll try it with 64 MB or less and see what's going on.

EDIT: It seems that you're absolutely correct! 4GB of RAM and 64MB of VRAM, blank screen. 65MB of VRAM, no problem. And the funny thing is that just last week I fixed a user's problem in the forums with the same problem without making the connection.

To summarize: EFI booting with more than 3504 MB of RAM and less than 64 MB of VRAM ends in black screen. Would you say that you agree with that?

[TylerLoch]

Fascinating how elusive these seemingly-simple bugs can be :)

Yes, I agree with your summary. Though I would suggest to clarify that this issue only affects EFI VMs with the ICH9 chipset configured. PIIX3 is not affected.

[Frank Mehnert]

Fixed in 5.1.24.

[Socratis]

This was never user-confirmed, so I tried it. 4096 MB RAM, 48 MB vRAM, OSX 10.11 guest with ICH9 chipset, VirtualBox 5.1.25 r117130 (Qt5.6.2).

I can confirm that it works as advertised.