Win7 x64 booting natively via EFI (no BIOS emulation)

[alex2013]

I recently bought a MBP 15" Haswell Retina...

I have been doing the same on the MBP 10,1 (15" Retina HD4000/GT650M) to get HD4000 working on Windows 8.1. Setting pci registers (exacly same as you mentioned) will not work to switch the graphics card. I think HD4000 needs more complicated initialization than just switching output and powering down discrete graphics on GMUX registers.

You have to boot to OSX, install gfxCardStatus and switch to "Integrated only" then restart. Do not swith off machine! After restart you will have internal graphics enabled. To be sure you can boot to EFI shell and check that GMUX registers are set to internal graphics, except register 750 has value 03 which means that NVIDIA power is still on.

You can turn NVIDIA off using:

echo Power down discrete graphics
mm 7C2 1 ;IO :1
stall 100000
mm 7D4 1 ;IO :50
stall 100000
mm 7C2 1 ;IO :0
stall 100000
mm 7D4 1 ;IO :50

And your screen shall not go black. After these commands it will not appear in Windows Device Manager. But this is quite optional - windows will use internal card anyway (actually a GOP protocol provided by EFI).

So now you can boot to Windows 8.1 and your internal graphics card will be used for output with "Basic Display Driver".

You can reboot, but not power off MBP - after power off or NVRAM reset discrete card will be used as default again.

I want to go further and install Intell HD4000 graphics drivers and this turned to real problem. After some expirements I've got the following results:

Prerequsites:
1. Applied image of Windows 8.1 Pro /sources/install.wim on GPT-partitioned USD-SSD using WAIK tools - I only would mention that you need EFI partition size of 1536MB if you installing on USB drive, otherwise you will get "Windows can not install on this configuration..." during setup. I dont know the exact reason for that.
2. Run OS X and set gfxCardStatus to use "Internal graphics only" then restart.
3. Hold option at startup to run Windows 8.1 setup from connected USB-HHD EFI partition.
3. Windows setup finishes OK and you can see that Intel graphics is enabled and running OK in Device Manager using "Basic Display Driver". Discrete NVIDIA card will have exclamation mark, its OK.

After that I try to install Intel HD graphics driver (tried both Bootcamp and latest from Intel website with the same result) - screen goes black and windows produces bugcheck then reboots. After that your windows installation is garbaged - it will boot then produce bugcheck again or will not boot at all. I did not use to boot safe mode because after some reboots it gives sporadic error with BCD etc. My point was to get memory dump from USD-SSD.

Bugcheck analisys of MEMORY.DMP gives:

6: kd> !analyze -v
*******************************************************************************
* *
* Bugcheck Analysis *
* *
*******************************************************************************

VIDEO_TDR_FAILURE (116)
Attempt to reset the display driver and recover from timeout failed.
Arguments:
Arg1: ffffe0000233e010, Optional pointer to internal TDR recovery context (TDR_RECOVERY_CONTEXT).
Arg2: fffff80001a43dc0, The pointer into responsible device driver module (e.g. owner tag).
Arg3: 0000000000000000, Optional error code (NTSTATUS) of the last failed operation.
Arg4: 000000000000000d, Optional internal context dependent data.

Debugging Details:
------------------


FAULTING_IP:
igdkmd64+fdc0
fffff800`01a43dc0 4889542410 mov qword ptr [rsp+10h],rdx

DEFAULT_BUCKET_ID: GRAPHICS_DRIVER_TDR_FAULT

BUGCHECK_STR: 0x116

PROCESS_NAME: System

CURRENT_IRQL: 0

ANALYSIS_VERSION: 6.3.9600.16384 (debuggers(dbg).130821-1623) amd64fre

STACK_TEXT:
ffffd000`22d0d738 fffff800`01727854 : 00000000`00000116 ffffe000`0233e010 fffff800`01a43dc0 00000000`00000000 : nt!KeBugCheckEx
ffffd000`22d0d740 fffff800`01727128 : fffff800`01a43dc0 ffffe000`0233e010 ffffd000`22d0d829 00000000`0000008e : dxgkrnl!TdrBugcheckOnTimeout+0xec
ffffd000`22d0d780 fffff800`01916516 : ffffe000`0233e010 ffffd000`22d0d829 00000000`00000000 00000000`000007fe : dxgkrnl!TdrIsRecoveryRequired+0x18c
ffffd000`22d0d7b0 fffff800`01948ae8 : 00000000`00000006 ffffd000`22d0d8b0 00000000`00000102 00000000`00000002 : dxgmms1!VidSchiReportHwHang+0x3ca
ffffd000`22d0d890 fffff800`01930a8c : ffffd000`00000002 00000000`00000102 00000000`00000002 ffffe000`02a6e000 : dxgmms1! ?? ::NNGAKEGL::`string'+0x4fc8
ffffd000`22d0d920 fffff800`01905df7 : ffffffff`ff676980 00000000`00000000 ffffd000`22d0dac0 00000000`00000000 : dxgmms1!VidSchiWaitForSchedulerEvents+0x26c
ffffd000`22d0d9c0 fffff800`0193da7a : ffffe000`02a6e000 ffffe000`02a6e000 ffffe000`038f54f0 ffffe000`00000000 : dxgmms1!VidSchiScheduleCommandToRun+0x437
ffffd000`22d0db70 fffff800`0193da4d : ffffe000`02a6e000 00000000`00000080 ffffe000`0034a080 ffffe000`0034a000 : dxgmms1!VidSchiRun_PriorityTable+0x2a
ffffd000`22d0dbc0 fffff803`32d73664 : fffff803`32fd5a80 ffffe000`0034a080 ffffd000`22d0dc90 fffff803`32ddf47d : dxgmms1!VidSchiWorkerThread+0x8d
ffffd000`22d0dc00 fffff803`32de26c6 : fffff803`32f7d180 ffffe000`0034a080 fffff803`32fd5a80 ffffe000`02abce48 : nt!PspSystemThreadStartup+0x58
ffffd000`22d0dc60 00000000`00000000 : ffffd000`22d0e000 ffffd000`22d08000 00000000`00000000 00000000`00000000 : nt!KiStartSystemThread+0x16


STACK_COMMAND: .bugcheck ; kb

FOLLOWUP_IP:
igdkmd64+fdc0
fffff800`01a43dc0 4889542410 mov qword ptr [rsp+10h],rdx

SYMBOL_NAME: igdkmd64+fdc0

FOLLOWUP_NAME: MachineOwner

MODULE_NAME: igdkmd64

IMAGE_NAME: igdkmd64.sys

DEBUG_FLR_IMAGE_TIMESTAMP: 50b7cf1b

FAILURE_BUCKET_ID: 0x116_IMAGE_igdkmd64.sys

BUCKET_ID: 0x116_IMAGE_igdkmd64.sys

ANALYSIS_SOURCE: KM

FAILURE_ID_HASH_STRING: km:0x116_image_igdkmd64.sys

FAILURE_ID_HASH: {2dd455a7-a731-ffcb-c3fd-14ce7783fc02}

Followup: MachineOwner
---------

IGD driver not responding. So now I am trying to figure out the problem. The same driver works on models without discrete GPU and not on models that have it. Will try to play with registry TdrLevel/TdrDelay etc...

P.S. I dont see any reason to use oWindows 8.1 with "Basic Display Driver" on intel hd graphics - no 3D and perfomance is degrated. In such case I would better have OS X parallels virtual machine running Windows 8.1 with power saving enabled that exacly utilizes internal graphics.

 

[jonaskello]

You have to boot to OSX, install gfxCardStatus and switch to "Integrated only" then restart. Do not swith off machine! After restart you will have internal graphics enabled. To be sure you can boot to EFI shell and check that GMUX registers are set to internal graphics, except register 750 has value 03 which means that NVIDIA power is still on.

Thanks! Got it one step further doing this. I can power down nvidia in EFI shell and the screen does not go black, just like you said! I also checked the source code for gfxCardStatus but it just calls an Apple API so it is not possible to derive from it what registers it sets etc.

However when I continue to boot Windows 8.1 I get the initial black screen with blue flag for like two seconds and then totally black screen. I think the screen goes black at about the point where the animated white dots should appear at the botton. Probably the bootloader is doing some graphics driver loading or similar at that point and it causes it to fall back to nvidia which does not work because it is not available. Same thing if I do not power down nvidia (just switch with gfxCardStatus in OSX and reboot to Windows).

I'll try to get some boot logging going and see if I can figure out what is happening at the point where the screen goes black. Bootlogging and other advanced startup options seem to be harder to set in Windows 8 tough, been unscucessful to get a bootlog so far but will keep trying. If anyone knows what happens in the Win8 boot process at the point where the white dots starts that would be useful info. Also input on how to log/debug the boot process in Win8 is much appreciated.

 

[Quackers]

Interesting.
I've had Windows 8 EFI booting on my rMBP 10,1 before. Installation was a pain to achieve but it worked in the end (apart from sound).
On the graphics side I had to disable the Intel device and remove its driver from /Windows/System32/drivers otherwise it would just black screen (or dark grey) on booting and continue to flash from black to dark grey and occasionally restart itself.
So, once that was done the Nvidia card worked and all was good (though this is not what some of you are after, obviously). At least it was usable for me.

Anyway, I thought I'd investigate Windows 8.1 in an EFI install to see if improvements have been made.

The installation was completely painless. Absolutely normal. No BCD problems or graphics hiccups.

Then I activated it and installed Bootcamp drivers and.............black screen
Even after entering safe mode and removing the Intel driver and disabling Intel graphics I can't get it to boot to a desktop. Doh!
I've upgraded the Nvidia driver to the latest WQHL driver (327 iirc) which worked previously, but not now it seems.
Device manager now reports that my PnP monitor has a yellow exclamation mark next to it but it also says it's working normally!
Interestingly on first boot there were 2 PnP monitors listed and both the Intel and Nvidia graphics chips were recognised. It was as if they had one screen for each gfx chip!

So, installation was great but not able to use it yet

I'll investigate some more

 

[eternalhack]

Bootcamp installed Win 8 to boot via EFI?

I have a late 2013 15" MBP 11,3 and this is my first foray into the world of Macs. After doing a bunch of reading I decided I wanted to boot Windows 8 via EFI. By using various older posts as a reference I attempted to install windows 8 from a USB flash drive by rebooting and choosing to boot the EFI installer. The installation got to the end and then exited with some message about not being able to update the BCD or something. After some brief research on the issue I decided I would save this adventure for a later time.

I then decided to settle for BIOS legacy boot and launched bootcamp assistant and started the installation this way. The 3 options on the first bootcamp assistant were surprisingly confusing to me. I let the assistant add the drivers and whatever else to the USB flash drive and it then rebooted my MBP and entered the windows 8 installer. To my surprise once the installation completed and I booted into windows it appeared Windows 8 was booting natively via EFI. I ran GPT fdisk (gdisk) and it showed I had a protective MBR and I also ran system information in Win 8 and it showed BIOS mode as "UEFI". Am I really booting via EFI? If I am then did something get updated in bootcamp assistant that now does the installation via EFI?

 

[Quackers]

I have a late 2013 15" MBP 11,3 and this is my first foray into the world of Macs. After doing a bunch of reading I decided I wanted to boot Windows 8 via EFI. By using various older posts as a reference I attempted to install windows 8 from a USB flash drive by rebooting and choosing to boot the EFI installer. The installation got to the end and then exited with some message about not being able to update the BCD or something. After some brief research on the issue I decided I would save this adventure for a later time.

I then decided to settle for BIOS legacy boot and launched bootcamp assistant and started the installation this way. The 3 options on the first bootcamp assistant were surprisingly confusing to me. I let the assistant add the drivers and whatever else to the USB flash drive and it then rebooted my MBP and entered the windows 8 installer. To my surprise once the installation completed and I booted into windows it appeared Windows 8 was booting natively via EFI. I ran GPT fdisk (gdisk) and it showed I had a protective MBR and I also ran system information in Win 8 and it showed BIOS mode as "UEFI". Am I really booting via EFI? If I am then did something get updated in bootcamp assistant that now does the installation via EFI?

Did you let Bootcamp create the Windows partition or did that partition already exist from your earlier attempt?
If you reboot and hold the Alt key after the chime what options appear in the boot menu? i.e. is the Windows boot option called Bootcamp, Windows or EFI boot?

 

[Sjmmon]

Can rMBP 15" late 2013 install win7 via Efi ?

 

[Quackers]

I've got my Windows 8.1 installation booting again.
The only way I could do that was to boot in to safe mode and uninstall the Intel HD4000 and the Nvidia GT650M and all installed drivers. Not the greatest user experience now then!
The system now boots to a desktop using the Microsoft Basic Driver.
Sadly as soon as I install a video driver (Intel, Nvidia 306, 327.02,327.23,331.82) the monitor shows a yellow exclamation mark in device manager (even though it says it's working fine) and it fails to boot - just goes to a backlit black screen.

This is different to Windows 8 on this machine, which worked ok with the Nvidia 327.23 driver.

Hey-ho

 

[eternalhack]

Did you let Bootcamp create the Windows partition or did that partition already exist from your earlier attempt?
If you reboot and hold the Alt key after the chime what options appear in the boot menu? i.e. is the Windows boot option called Bootcamp, Windows or EFI boot?

The Windows boot option is called "Windows". I'm not sure who created the partition because I've been messing around a lot. I'm pretty sure bootcamp assistant created a partition but when it booted into the installer it wouldn't allow me to install on that partition so I had to choose to format it to NTFS from within the windows 8 installer and then it allowed me to continue.

 

[Quackers]

The Windows boot option is called "Windows". I'm not sure who created the partition because I've been messing around a lot. I'm pretty sure bootcamp assistant created a partition but when it booted into the installer it wouldn't allow me to install on that partition so I had to choose to format it to NTFS from within the windows 8 installer and then it allowed me to continue.

Thanks.
If you have a look at the link below you may be able to find out which way Windows is booting.
http://blogs.technet.com/b/home_is_where_i_lay_my_head/archive/2012/10/02/how-to-check-in-windows-if-you-are-using-uefi.aspx

In short, if you go to search and type in "msinfo32" without quotes, then click on the corresponding entry below the search box, then look down the page that then appears until you see
BIOS Mode
next to that will be an entry. Mine says UEFI and mine is an EFI installation.
I suspect it will say "legacy" or "bios" if yours is not an EFI installation.

 

[eternalhack]

Thanks.
If you have a look at the link below you may be able to find out which way Windows is booting.
http://blogs.technet.com/b/home_is_where_i_lay_my_head/archive/2012/10/02/how-to-check-in-windows-if-you-are-using-uefi.aspx

In short, if you go to search and type in "msinfo32" without quotes, then click on the corresponding entry below the search box, then look down the page that then appears until you see
BIOS Mode
next to that will be an entry. Mine says UEFI and mine is an EFI installation.
I suspect it will say "legacy" or "bios" if yours is not an EFI installation.

Yeah, I mentioned in my previous post it shows "UEFI". It's just strange because I've found some threads from late 2013 MBP owners and no one has mentioned the behavior I am seeing.

 

[Quackers]

Yes it does appear to be a little odd but it seems you've got an EFI installation
Just out of interest, does sound work ok?

 

[eternalhack]

Yes it does appear to be a little odd but it seems you've got an EFI installation
Just out of interest, does sound work ok?

I'll check it out and let you know, but I do know the keyboard backlight setting isn't saved across reboots which is annoying.

 

[Quackers]

I'll check it out and let you know, but I do know the keyboard backlight setting isn't saved across reboots which is annoying.

Lol,I'll swap my keyboard backlight for your graphics and (possibly) sound

 

[eternalhack]

Lol,I'll swap my keyboard backlight for your graphics and (possibly) sound

Sound is working . You have the MBP 10,1, right? I'm guessing the EFI firmware on my MBP 11,3 is updated or the drivers are so things work right. The strange thing to me is that bootcamp assistant seemingly chose the EFI installer itself. I'm new to macs and am still trying to figure out exactly what bootcamp assistant is doing.

 

[Quackers]

Sound is working . You have the MBP 10,1, right? I'm guessing the EFI firmware on my MBP 11,3 is updated or the drivers are so things work right. The strange thing to me is that bootcamp assistant seemingly chose the EFI installer itself. I'm new to macs and am still trying to figure out exactly what bootcamp assistant is doing.

Yes I have the 10,1. Some previous versions have sound in EFI and some don't.
I'm glad to hear yours is working (like some of the 2013 MacBook Airs, which can seemingly boot in EFI mode too via Boot Camp).
Hopefully firmware updates will be forthcoming for we underlings (though I doubt it).
Still, it's not a great problem that I have no sound - I can always use Mavericks for that.
What is of greater importance is the lack of graphics acceleration at the moment. It's very laggy on Microsoft basic driver
It's all the more upsetting as I had a Nvidia driver working in 8.1 a couple of weeks ago, so something has changed.
I've tried every Nvidia driver I can get my hands on and they all knock out the "PnP Monitor" as soon as the GT650M is recognised as such. Same result in safe mode too.

 

[eternalhack]

Yes I have the 10,1. Some previous versions have sound in EFI and some don't.
I'm glad to hear yours is working (like some of the 2013 MacBook Airs, which can seemingly boot in EFI mode too via Boot Camp).
Hopefully firmware updates will be forthcoming for we underlings (though I doubt it).
Still, it's not a great problem that I have no sound - I can always use Mavericks for that.
What is of greater importance is the lack of graphics acceleration at the moment. It's very laggy on Microsoft basic driver
It's all the more upsetting as I had a Nvidia driver working in 8.1 a couple of weeks ago, so something has changed.
I've tried every Nvidia driver I can get my hands on and they all knock out the "PnP Monitor" as soon as the GT650M is recognised as such. Same result in safe mode too.

Yeah, hopefully you have some updates forthcoming. I did just see another post from a user confirming the behavior I experienced regarding UEFI boot with the late 2013 MBP.

 

[Quackers]

Can somebody correct me here please?
I don't remember the Intel HD4000 ever being recognised as such in device manager in an EFI install of windows 8. In fact, I think I read somewhere that Apple's implementation of EFI switches off the Intel card in Windows (some would say that it's to stop Windows acheiving better battery life).

However, as you can see from the first attachment below the Intel chip is recognised in my new Windows 8.1 EFI installation. It can be chosen in device manager but even though it shows as working normally, it doesn't in fact work. No graphics acceleration is present when it as activated, so I assume the Microsoft Basic Display driver is actually being used. This is borne out by the fact that if I activate the Intel card and disable the Basic display driver (which is for the Nvidia GT650M - but with no Nvidia driver installed) the system will not boot to a desktop - just to a black (backlit) screen.

A most puzzling aspect is that if I try to install any Nvidia driver the Nvidia GT650M is recognised but as soon as that happens the monitor develops a yellow triangle with an exclamation mark (even though it says it's working normally) - attachment 2 - and the system fails to boot - another black screen.

This was not the case in my Windows 8 EFI install. In that case the Nvidia drivers worked and the Intel chip did not appear at all in device manager.

Can others confirm their experience in this respect please?
Thanks.

 

[eternalhack]

Can somebody correct me here please?
I don't remember the Intel HD4000 ever being recognised as such in device manager in an EFI install of windows 8. In fact, I think I read somewhere that Apple's implementation of EFI switches off the Intel card in Windows (some would say that it's to stop Windows acheiving better battery life).

In that first screenshot on the left you disabled the NVIDIA GPU, right? On my MBP 11,3 Windows 8.1 EFI installation I only see the NVIDIA GeForce GT 750M under display adapters in device manager.

 

[Quackers]

In that first screenshot on the left you disabled the NVIDIA GPU, right? On my MBP 11,3 Windows 8.1 EFI installation I only see the NVIDIA GeForce GT 750M under display adapters in device manager.

No, in the first screenshot the Nvidia card is using the MS Basic display driver - not disabled.
The Nvidia card is only recognised as such once a Nvidia driver is installed, which causes the monitor to get a yellow triangle with exclamation mark, and stop working.

I'm sure I used to see only one device under display adapters in my previous EFI Windows 8 installs. Thanks.

I wonder if something has changed with Apple, Windows or my machine? Maybe Windows 8.1, perhaps?

 

[Quackers]

I've just had an interesting few hours - even bizarre, perhaps

Not happy with no graphics acceleration at all in my last EFI install I decided to try a new install through Boot Camp but still in EFI mode, to see if I could get anything to happen.

First I mounted the Windows.iso (Windows 8.1) in OSX and then copy/pasted all files and folders on to a 8GB flash drive formatted in FAT32 (in an effort to ensure I got the EFI Boot option).
I also copied across all the 5033 Bootcamp support drivers and the unattended.xml to the same flash drive
I tested this on reboot and it worked ok.

Then I fired up gdisk and deleted my OSX recovery partition and my previous Windows EFI partitions (both of them).
I then returned my OSX drive to just an EFI partition and an OSX partition so that BootCamp could do its thing. (After rebooting to make sure all was good).

I let BC create the partition for Windows but did not reboot when told to.
I fired up gdisk again and created a new protective mbr (over-writing the BC created hybrid mbr).
I checked to see that all partitions were looking good and still recognised correctly by GPT. All good.

I rebooted to make sure all was good. It was.

I shutdown and inserted the USB flash drive and fired up the system holding Alt.
I chose the EFI Boot option with the USB logo (orange) and the installer appeared. It looked different from previous installer windows. It was not blue surrounded but white - like an unfocused window in Windows - and it was very small! I got my glasses out so I could read it!

I ran through the procedure but when I got to the partition stage it baulked. I noticed it had already created a MSR partition and the remaining space of the BC created partition was unusable so I just told it to format that and that was ok. I told it to install to that partition and a few minutes later the install was complete and after a reboot the setup screen appeared.
It displayed the normal messages but it was somewhat slower than previous attempts. In fact the last screen, which was headed "almost finished" was there for at least 10 minutes.
Anyway I just left it and it did finish and after another reboot I was ready to setup my account and stuff.
Everything finished and the desktop appeared.
The Bootcamp installer then appeared and (with a few apparent visual glitches) it ran and got everything installed. No error messages.

I ran to device manager and saw that both the Intel HD4000 and the Nvidia GT650M were recognised and had drivers installed and working.
The Nvidia card was using the 306.37 driver from the Bootcamp support drivers.
I had graphics acceleration too! Luvverly!
No sound though, as expected.

I ran Windows updates and installed all the recommended updates one bit at a time, restarting as necessary. Then came the optional updates - an Intel graphics driver and an Nvidia driver (327.02).

Didn't fancy these so I created a restore point and ran the Intel one. It went ok and after a restart nothing had changed.
I then ran the Nvidia one and after a restart black screen (backlit).

This is where my problems began. I rebooted in to safe mode and viewed device manager. It reported that the monitor, though apparently functioning normally, had a yellow triangle with an exclamation mark.

To get back to where I started I uninstalled the Nvidia driver from Programs and Features (which is what the Nvidia site recommends) and uninstalled both the monitor and the GT650M and its drivers.
I deleted the Nvidia corporation folder in the root of the drive too, so it couldn't sneak the driver back in.
I rebooted to a normal desktop though device manager reported that the MS Basic Display driver was in use by the GT650M.

I disabled the Intel graphics chip, as I was pretty sure it was doing nothing anyway.
But, as I had the device driver window open the Nvidia GT650M re-appeared with the 327.02 driver re-installed!
Where did that come from? I deleted everything.

And so a 2 hour reboot/uninstall driver loop began and every time the 327.02 driver was re-installed.

Anyway I managed to get things sorted in the end by booting into safe mode and re-running the 306.37 installer from the Bootcamp support drivers folder.
That worked and I still have that driver installed now and I have graphics acceleration again.

Interestingly, Windows thinks I have 2 monitors now. On a laptop!
I'm presuming one is for the Intel and one for the Nvidia. Can't think of anything else

I'm also presuming that the acceleration is due to the Nvidia card and driver though I don't know how to check that.

What do you guys think?

 

[mark1234]

Very interesting, from your story I come to the conclusion that the display driver for NVIDIA has to be the NVIDIA driver supplied with Bootcamp. When the NVIDIA driver is from Microsoft or NVIDIA itself, it does not work anymore.
When my observation is right, then it would mean that Apple has some prioprietary things included in the NVIDIA which only work when using the proprietary NVIDIA driver from Bootcamp.

 

[Quackers]

Very interesting, from your story I come to the conclusion that the display driver for NVIDIA has to be the NVIDIA driver supplied with Bootcamp. When the NVIDIA driver is from Microsoft or NVIDIA itself, it does not work anymore.
When my observation is right, then it would mean that Apple has some prioprietary things included in the NVIDIA which only work when using the proprietary NVIDIA driver from Bootcamp.

Yes it would seem that's a possibility, although I am unaware of anything specific.
However, when I had a Windows 8 installation and wanted to upgrade to Windows 8.1 it would not allow the update. I first had to upgrade the Nvidia driver to version 327.23, then the upgrade continued and Windows 8.1 ran fine.
That is no longer true in this latest EFI fresh install of Windows 8.1 and is curious.
No Nvidia drivers would work at first, which is why I tried the Bootcamp method.
At least that now gives me some graphics acceleration.

Interestingly, though Bootcamp and Disk Utility recognise my Windows partition as a "BOOTCAMP" partition, the bootcamp utility will not allow the disk to be returned to one partition and will not allow the current Windows installation to be removed via BC (that option is greyed out).
The boot + Alt menu calls it EFI Boot, rather than BOOTCAMP.
So it knows there is a Bootcamp partition but doesn't want to use it - I think.

 

[Quackers]

Incidentally the 2 screens shown in my screenshot above are not for the Nvidia and Intel cards (one for each).
They are for the Nvidia card and the Microsoft Basic Display driver.
Not sure what that's all about really

 

[eternalhack]

It is frustrating that this has to be this difficult. Other people with the late 2013 MBP 11,3 like mine are having issues installing to boot via EFI and somehow I didn't have any. There has to be some explanation for this but no one has figured it out yet.

 

[Quackers]

It is frustrating that this has to be this difficult. Other people with the late 2013 MBP 11,3 like mine are having issues installing to boot via EFI and somehow I didn't have any. There has to be some explanation for this but no one has figured it out yet.

I agree! The inconsistencies between people's experiences are amazing - even with the same hardware sometimes.
It's almost a lottery, it seems