OC: NVRAM emulation, EFI_GLOBAL_VARIABLE_GUID, and Default Boot Entry with Startup Disk

[williambj1]

Feature Request

Add support for NVRAM write fix (or emulation) for EFI_GLOBAL_VARIABLE_GUID in OpenCore/FwRuntimeServices for devices that don't have working hardware NVRAM in macOS to make boot entry setting fully functional.

Background

After discussing in a Chinese chat group community for nearly 1 month, we figured out how this is related to NVRAM emulation and the setting of OpenCore's default boot option.

---

We experimented 3 different motherboards (Z390, C621 & HM370) and got the same results

Both tests are under these conditions:

• DisableVariableWrite = Yes
• LegacyEnable = YES
• RequestBootVarRouting = YES
• ScanPolicy = 0
• ExposeSensitiveData = 0x03
• FwRuntimeServices included
• Hardware NVRAM reseted before each test (without VariableRuntimeDxe)
• OpenCore's default boot item is BootCamp Windows
• VariableRuntimeDxe compiled with emulation enabled

Boot0080 and BootOrder is NOT present under NVRAM/Block

Test 1: (Booted without VariableRuntimeDxe)

1. Set Startup disk to Macintosh HD

2. In Terminal:

   $ sudo nvram -x '8BE4DF61-93CA-11D2-AA0D-00E098032B8C:Boot0080' | /usr/bin/sed '/\<data\>/,/\<\/data\>/!d;//d' | /usr/bin/base64 --decode`
   nvram: Error getting variable - '8BE4DF61-93CA-11D2-AA0D-00E098032B8C:Boot0080': (iokit/common) data was not found
   
   $ sudo nvram boot-args
   boot-args    <Empty>
   
   $ sudo nvram boot-args="-v"
   
   $ sudo nvram boot-args
   boot-args    -v

3. Entry 8BE4DF61-93CA-11D2-AA0D-00E098032B8C is not present in nvram.plist dumped by LogoutHook

4. Restart and OpenCore's default boot option is still BootCamp Windows

Test 2: (Booted with VariableRuntimeDxe)

1. Set Startup disk to Macintosh HD

2. In Terminal:

   $ sudo nvram -x '8BE4DF61-93CA-11D2-AA0D-00E098032B8C:Boot0080' | /usr/bin/sed '/\<data\>/,/\<\/data\>/!d;//d' | /usr/bin/base64 --decode`
   Mac OS X
           �A
   %8W��2��a�e�V�Q�x�I�7OJ
   ��D$��t�|
            �I�G�.hB5�|̏�@��I����
                                �\(Whatever UUID)\System\Library\CoreServices\boot.efi�%
   
   $ sudo nvram boot-args
   boot-args    <Empty>
   
   $ sudo nvram boot-args="-v"
   
   $ sudo nvram boot-args
   boot-args    -v

3. Entry 8BE4DF61-93CA-11D2-AA0D-00E098032B8C this time is present in nvram.plist dumped by LogoutHook

4. Restart and OpenCore's default boot option is still BootCamp Windows

   • HOWEVER, if VariableRuntimeDxe is removed before restart at this moment, OpenCore's default boot option will successfully change into Macintosh HD

Conclusion

• It seems that macOS can read and write variables into APPLE_NVRAM_VARIABLE_GUID but fails to write into EFI_GLOBAL_VARIABLE_GUID
• To get correct values from EFI_GLOBAL_VARIABLE_GUID (Boot0080, BootOrder, etc.), an Emulated NVRAM layer must be used
• OpenCore fails to read the default boot order from nvram.plist when VaribleRuntimeDxe is present
• The default boot order is unchangeable unless a new nvram.plist is generated with VariableRuntimeDxe, which is quite inconvenient

Questions

1. Is VariableRuntimeDxe completely replaced by OpenCore + FwRuntimeServices? (ref:https://github.com/cattyhouse/oc-guide/blame/33f657e44a1c372a7d1bcb1553b0947c3f2a28cf/README.md#L8) CC @cattyhouse
2. What's the behavior of NVRAM resetting and Boot order setting in OpenCore when VariableRuntimeDxe is present?

Related issues comments:

#459 (comment)
#495 (comment)
#575 (comment)

Thanks for your patience for reading these words, we highly admire your hard work and respect your time. If this is non-sense, feel free to close this.

Edit[1]: Change links, add more details
Edit[2]: Terminal Copy-Paste error
Edit[3]: Clearity

[vit9696]

I think the issue is that DisableVariableWrite simply error-exits SetVariable interface in FwRuntimeServices.efi. Unlike APPLE_BOOT_VARIABLE_GUID, other GUIDs are not cached and are written immediately, thus saving and retrieving them with the script does not work.

  if (gCurrentConfig->WriteProtection) {
    return EFI_SECURITY_VIOLATION;
  }

To resolute this FwRuntimeServices will need setting/getting NVRAM variables to/from some memory structure. Feel free to contribute.

[williambj1]

@vit9696 Thanks for your reply!

I'd really want to contribute but unfortunately, I have very limited knowledge in C and no experience in EDK2 at all. The only related code I could understand is the LogoutHook script. I apologize that I can't handle this.

[meaganmargaret]

Any progress on this? Because it is, at least for me and my system, a major failing. I cannot reliably set the boot order with OpenCore.

I also am not a programmer, but I would offer my Asus Sage system up for testing and experimentation, if that's of any value.

[errorexists]

Any progress on this? Because it is, at least for me and my system, a major failing. I cannot reliably set the boot order with OpenCore.

I also am not a programmer, but I would offer my Asus Sage system up for testing and experimentation, if that's of any value.

read here for NVRAM
acidanthera/OpenCorePkg@a825da4
https://www.hackintosh-forum.de/forum/thread/46154-natives-nvram-auf-dem-z390-durchbruch/

[meaganmargaret]

Errorexists:

Please don't assume I haven't read those references.
A Z390 system does NOT equal an Asus Sage X299 system! Not the same and they don't work on X299 systems.

I want OC to respect and USE the proper boot order on my system (an X299 Asus Sage), and these changes don't work! The may work for a Z390 system, but that is NOT my system!

[errorexists]

Errorexists:

Please don't assume I haven't read those references.
A Z390 system does NOT equal an Asus Sage X299 system! Not the same and they don't work on X299 systems.

I want OC to respect and USE the proper boot order on my system (an X299 Asus Sage), and these changes don't work! The may work for a Z390 system, but that is NOT my system!

Any progress on this? Because it is, at least for me and my system, a major failing. I cannot reliably set the boot order with OpenCore.

I also am not a programmer, but I would offer my Asus Sage system up for testing and experimentation, if that's of any value.

hold your horses their you did not "specify" that it was a x299 system now did you
if you also read this has nothing to do with a x299

[ghost]

Specifying the Chipset would be helpful :)

[meaganmargaret]

The original post I responded to was about boot order, which is still broken on an X299 C621 system running OC.  It does NOT work, even with all of the SSDTs that have been put out.  I tried them.  I don't care if my system can print "myvar  test", when the boot order is not respected. And really if OC can't do this, well, I really don't care if it's done via nvram or an external menu system, as long as it respects the boot order I want it to respect. OC, in my view, is still broken. InsanelyHack wrote on 1/26/20 1:30 PM:

…

Specifying the Chipset would be helpful :) — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#580?email_source=notifications&email_token=AELIXD4MABZE5WT3BXQYCLTQ7X6G7A5CNFSM4JOI7LC2YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEJ56NMA#issuecomment-578545328>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AELIXD6CETEFXIN5HQMXSCLQ7X6G7ANCNFSM4JOI7LCQ>.

[errorexists]

well you need NVRAM to bless the drive an that is accomplished from selecting the boot drive from the startup in the system pref

[meaganmargaret]

Okay, I'll try one more time.

Here's the original request: "......OpenCore/FwRuntimeServices for devices that don't have working hardware NVRAM in macOS to make boot entry setting fully functional...."

And also: the originator of this request, williambj1, posted that he would offer three different motherboards for testing, and one of them was: C621, which is an X299 motherboard. So the purpose of this feature request was to deal with the C621 (on mostly Asus boards) NVRAM and OC's failure to respect boot order. That was the purpose of the request.

Well, maybe they now have NVRAM, but it doesn't matter. On an X299 C621 system, nvram or not, the "...make boot entry setting fully functional...." does NOT work.

I've set the boot order any number of times (like over a hundred - and yes that means rebooting that many times), and it doesn't work.

[errorexists]

NVRAM is not supported for the x299 an x99 as read here
https://khronokernel-2.gitbook.io/opencore-vanilla-desktop-guide/post-install/nvram

[meaganmargaret]

I've also read that. I'm looking for work-arounds.

This is pointless.

[cattyhouse]

Errorexists:

Please don't assume I haven't read those references.
A Z390 system does NOT equal an Asus Sage X299 system! Not the same and they don't work on X299 systems.

I want OC to respect and USE the proper boot order on my system (an X299 Asus Sage), and these changes don't work! The may work for a Z390 system, but that is NOT my system!

Stay hungry, stay foolish.

[vit9696]

We do not plan to work on this issue, but we can consider contributed patches.