From 4c2fa234c4c092a9872b0c8a31ccd85357a2d249 Mon Sep 17 00:00:00 2001
From: Dmitry Borisov <di.sean@protonmail.com>
Date: Mon, 22 Jun 2026 18:06:15 +0600
Subject: [PATCH] [FREELDR:PC98] Report a more detailed system ID for sysdm
 control panel (#9194)

Report the machine model name for better user experience.

CORE-17977
---
 boot/freeldr/freeldr/arch/i386/pc98/pc98hw.c | 68 +++++++++++++++++++-
 1 file changed, 67 insertions(+), 1 deletion(-)

diff --git a/boot/freeldr/freeldr/arch/i386/pc98/pc98hw.c b/boot/freeldr/freeldr/arch/i386/pc98/pc98hw.c
index e7a2cb6e9d7..f6964e2aa0d 100644
--- a/boot/freeldr/freeldr/arch/i386/pc98/pc98hw.c
+++ b/boot/freeldr/freeldr/arch/i386/pc98/pc98hw.c
@@ -1161,6 +1161,72 @@ DetectPnpBios(PCONFIGURATION_COMPONENT_DATA SystemKey, ULONG *BusNumber)
     (*BusNumber)++;
 }
 
+static
+PCSTR
+GetPc9821SystemIdentifier(
+    _In_ UCHAR Id)
+{
+    switch (Id)
+    {
+        case 0x27: return "Lt2";
+        case 0x30: return "Cx3";
+        case 0x40: return "Ct16";
+        case 0x59: return "V166";
+        case 0x5F: return "Nr166";
+        case 0x73: return "Ra333";
+        default:   return NULL;
+    }
+}
+
+static
+VOID
+CreateSystemKey(
+    _Inout_ PCONFIGURATION_COMPONENT_DATA* SystemKey)
+{
+    const ULONG IdentifierSize = 256;
+    PCHAR Identifier;
+
+    /* The kernel expects the PC-98 identifier string to begin with 'NEC PC-98' */
+#define PC98_DEFAULT_ID  "NEC PC-98"
+
+    Identifier = FrLdrHeapAlloc(IdentifierSize, TAG_HW_RESOURCE_LIST);
+    if (!Identifier)
+        return;
+
+    /* Check if this machine is NEC PC-9821 */
+    if (*(PUSHORT)MEM_EXTENDED_NORMAL == 0x2198)
+    {
+        UCHAR Id = *((PUCHAR)MEM_EXTENDED_NORMAL + 0x3F);
+        PCSTR IdString;
+
+        IdString = GetPc9821SystemIdentifier(Id);
+        if (!IdString)
+        {
+            /* Unknown values should be visible in sysdm control panel for bug reports */
+            ERR("Unknown PC-9821 model %02X\n", Id);
+            RtlStringCbPrintfA(Identifier,
+                               IdentifierSize,
+                               PC98_DEFAULT_ID "21 Unknown model %02X",
+                               Id);
+        }
+        else
+        {
+            RtlStringCbPrintfA(Identifier,
+                               IdentifierSize,
+                               PC98_DEFAULT_ID "21 %s",
+                               IdString);
+        }
+    }
+    else
+    {
+        RtlStringCbCopyA(Identifier, IdentifierSize, PC98_DEFAULT_ID);
+    }
+    TRACE("System identifier '%s'\n", Identifier);
+
+    FldrCreateSystemKey(SystemKey, Identifier);
+    FrLdrHeapFree(Identifier, TAG_HW_RESOURCE_LIST);
+}
+
 PCONFIGURATION_COMPONENT_DATA
 Pc98HwDetect(
     _In_opt_ PCSTR Options)
@@ -1171,7 +1237,7 @@ Pc98HwDetect(
     TRACE("DetectHardware()\n");
 
     /* Create the 'System' key */
-    FldrCreateSystemKey(&SystemKey, "NEC PC-98");
+    CreateSystemKey(&SystemKey);
 
     GetHarddiskConfigurationData = Pc98GetHarddiskConfigurationData;