From 7f433ed74de104db31cb790c9b2cd3dabd7bf465 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Herm=C3=A8s=20B=C3=A9lusca-Ma=C3=AFto?=
 <hermes.belusca-maito@reactos.org>
Date: Wed, 8 Apr 2026 22:53:29 +0200
Subject: [PATCH] [NTOS:CM] CmpSetSystemValues(): Export the Vista+
 "FirmwareBootDevice" registry value

In the `HKLM\SYSTEM\CurrentControlSet\Control` registry key,
the `FirmwareBootDevice` value specifies the firmware boot
(i.e. system partition) device in ARC format, obtained from
`LoaderBlock->ArcHalDeviceName`.
For some reason it is exposed only on Windows Vista and later.

This value is similar to the `SystemBootDevice` one, which specifies
instead the OS boot device in ARC format, obtained from
`LoaderBlock->ArcBootDeviceName`.

In addition: check the value returned by `RtlCreateUnicodeStringFromAsciiz()`
and fail if so.
---
 ntoskrnl/config/cmsysini.c | 33 +++++++++++++++++++++++++++------
 1 file changed, 27 insertions(+), 6 deletions(-)

diff --git a/ntoskrnl/config/cmsysini.c b/ntoskrnl/config/cmsysini.c
index df1de46a210..8ea6caf7b42 100644
--- a/ntoskrnl/config/cmsysini.c
+++ b/ntoskrnl/config/cmsysini.c
@@ -409,8 +409,7 @@ CmpSetSystemValues(IN PLOADER_PARAMETER_BLOCK LoaderBlock)
 
     /* Setup attributes for loader options */
     RtlInitUnicodeString(&KeyName,
-                         L"\\REGISTRY\\MACHINE\\SYSTEM\\CurrentControlSet\\"
-                         L"Control");
+                         L"\\REGISTRY\\MACHINE\\SYSTEM\\CurrentControlSet\\Control");
     InitializeObjectAttributes(&ObjectAttributes,
                                &KeyName,
                                OBJ_CASE_INSENSITIVE,
@@ -431,19 +430,41 @@ CmpSetSystemValues(IN PLOADER_PARAMETER_BLOCK LoaderBlock)
     if (!NT_SUCCESS(Status))
         goto Quit;
 
-    /* Setup the value for the system boot device in ARC format */
+    /* Setup the value for the OS boot device in ARC format */
     RtlInitUnicodeString(&KeyName, L"SystemBootDevice");
-    RtlCreateUnicodeStringFromAsciiz(&ValueName, LoaderBlock->ArcBootDeviceName);
+    if (!RtlCreateUnicodeStringFromAsciiz(&ValueName, LoaderBlock->ArcBootDeviceName))
+    {
+        Status = STATUS_UNSUCCESSFUL;
+        goto Quit;
+    }
     Status = NtSetValueKey(KeyHandle,
                            &KeyName,
                            0,
                            REG_SZ,
                            ValueName.Buffer,
                            ValueName.Length);
-
-    /* Free the temporary string */
     RtlFreeUnicodeString(&ValueName);
 
+    if (!NT_SUCCESS(Status))
+        goto Quit;
+
+#if (NTDDI_VERSION >= NTDDI_VISTA) || defined(__REACTOS__)
+    /* Setup the value for the firmware boot (i.e. system partition) device in ARC format */
+    RtlInitUnicodeString(&KeyName, L"FirmwareBootDevice");
+    if (!RtlCreateUnicodeStringFromAsciiz(&ValueName, LoaderBlock->ArcHalDeviceName))
+    {
+        Status = STATUS_UNSUCCESSFUL;
+        goto Quit;
+    }
+    Status = NtSetValueKey(KeyHandle,
+                           &KeyName,
+                           0,
+                           REG_SZ,
+                           ValueName.Buffer,
+                           ValueName.Length);
+    RtlFreeUnicodeString(&ValueName);
+#endif
+
 Quit:
     /* Close the key and return */
     NtClose(KeyHandle);