OcAppleSecureBootLib: Added BridgeOSHardwareModel NVRAM variable

This variable is derived from `SecureBootModel` specified in the config (e.g. j137 becomes J137AP) and is used by macOS 12 during updates and installations. Setting this variable allows to use macOS 12 with T2 board identifiers, e.g. j137.
jspraul · Oct 3, 2021 · 7cd3db3 · 7cd3db3
1 parent 102ede5
commit 7cd3db3
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Showing 8 changed files with 35 additions and 2 deletions.
diff --git a/Changelog.md b/Changelog.md
@@ -8,6 +8,7 @@ OpenCore Changelog
 - Added large BaseSystem support in `AdviseFeatures`
 - Updated builtin firmware versions for SMBIOS and the rest
 - Added tool to extract vendor secure boot certificate from GRUB shim file
+- Added `BridgeOSHardwareModel` NVRAM variable to fix T2 SB AP models on macOS 12
 
 #### v0.7.3
 - Improved SSDT-PNLF compatibility with CFL+ graphics

diff --git a/Docs/Configuration.pdf b/Docs/Configuration.pdf
diff --git a/Docs/Configuration.tex b/Docs/Configuration.tex
@@ -4532,6 +4532,12 @@ \subsection{Recommended Variables}\label{nvramvarsrec}
 
 \begin{itemize}
 \tightlist
+\item
+  \texttt{4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14:BridgeOSHardwareModel}
+  \break
+  Bridge OS hardware model variable used to propagate to IODT bridge-model
+  by \texttt{EfiBoot}. Read by \texttt{hw.target sysctl}, used by
+  SoftwareUpdateCoreSupport.
 \item
   \texttt{7C436110-AB2A-4BBB-A880-FE41995C9F82:csr-active-config}
   \break

diff --git a/Docs/Differences/Differences.pdf b/Docs/Differences/Differences.pdf
diff --git a/Docs/Differences/Differences.tex b/Docs/Differences/Differences.tex
@@ -1,7 +1,7 @@
 \documentclass[]{article}
 %DIF LATEXDIFF DIFFERENCE FILE
 %DIF DEL PreviousConfiguration.tex   Sun Sep 12 01:31:15 2021
-%DIF ADD ../Configuration.tex        Wed Sep 22 18:46:43 2021
+%DIF ADD ../Configuration.tex        Sun Oct  3 07:48:42 2021
 
 \usepackage{lmodern}
 \usepackage{amssymb,amsmath}
@@ -4606,7 +4606,13 @@ \subsection{Recommended Variables}\label{nvramvarsrec}
 \begin{itemize}
 \tightlist
 \item
-  \texttt{7C436110-AB2A-4BBB-A880-FE41995C9F82:csr-active-config}
+  \DIFaddbegin \texttt{\DIFadd{4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14:BridgeOSHardwareModel}}
+  \break
+  \DIFadd{Bridge OS hardware model variable used to propagate to IODT bridge-model
+  by }\texttt{\DIFadd{EfiBoot}}\DIFadd{. Read by }\texttt{\DIFadd{hw.target sysctl}}\DIFadd{, used by
+  SoftwareUpdateCoreSupport.
+}\item
+  \DIFaddend \texttt{7C436110-AB2A-4BBB-A880-FE41995C9F82:csr-active-config}
   \break
   32-bit System Integrity Protection bitmask. Declared in XNU source code in
   \href{https://opensource.apple.com/source/xnu/xnu-4570.71.2/bsd/sys/csr.h.auto.html}{csr.h}.

diff --git a/Docs/Errata/Errata.pdf b/Docs/Errata/Errata.pdf
diff --git a/Library/OcAppleSecureBootLib/OcAppleSecureBootLib.c b/Library/OcAppleSecureBootLib/OcAppleSecureBootLib.c
@@ -92,6 +92,8 @@ OcAppleSecureBootBootstrapValues (
   )
 {
   EFI_STATUS  Status;
+  CHAR8       BridgeModel[16];
+  UINTN       BridgeModelSize;
 
   ASSERT (Model != NULL);
 
@@ -106,6 +108,23 @@ OcAppleSecureBootBootstrapValues (
     return Status;
   }
 
+  for (BridgeModelSize = 0; mSbHardwareModel[BridgeModelSize] != '\0'; ++BridgeModelSize) {
+    BridgeModel[BridgeModelSize] = AsciiCharToUpper (mSbHardwareModel[BridgeModelSize]);
+  }
+  BridgeModel[BridgeModelSize] = '\0';
+
+  Status = gRT->SetVariable (
+    APPLE_BRIDGE_OS_HARDWARE_MODEL_VARIABLE_NAME,
+    &gAppleVendorVariableGuid,
+    EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
+    BridgeModelSize,
+    BridgeModel
+    );
+
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
   Status = gRT->SetVariable (
     L"HardwareModel",
     &gAppleSecureBootVariableGuid,

diff --git a/Library/OcAppleSecureBootLib/OcAppleSecureBootLib.inf b/Library/OcAppleSecureBootLib/OcAppleSecureBootLib.inf
@@ -37,6 +37,7 @@
 
 [Guids]
   gAppleSecureBootVariableGuid  ## SOMETIMES_CONSUMES
+  gAppleVendorVariableGuid      ## SOMETIMES_CONSUMES
 
 [Protocols]
   gAppleSecureBootProtocolGuid        ## SOMETIMES_PRODUCES