[edk2-devel] [PATCH v2 2/3] OvmfPkg/PlatformPei: prefer etc/e820 for memory detection

Gerd Hoffmann kraxel at redhat.com
Thu Aug 26 09:55:39 UTC 2021


Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3593

Prefer the e820 map provided via qemu firmware config interface
for memory detection.  Use rtc cmos only as fallback, which should
be rarely needed these days as qemu supports etc/e820 since 2013.

Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
Reviewed-by: Philippe Mathieu-Daude <philmd at redhat.com>
---
 OvmfPkg/PlatformPei/MemDetect.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/OvmfPkg/PlatformPei/MemDetect.c b/OvmfPkg/PlatformPei/MemDetect.c
index d7fb3e742be3..20154255324b 100644
--- a/OvmfPkg/PlatformPei/MemDetect.c
+++ b/OvmfPkg/PlatformPei/MemDetect.c
@@ -293,9 +293,16 @@ GetSystemMemorySizeBelow4gb (
   VOID
   )
 {
+  EFI_STATUS Status;
+  UINT64 LowerMemorySize = 0;
   UINT8 Cmos0x34;
   UINT8 Cmos0x35;
 
+  Status = ScanOrAdd64BitE820Ram (FALSE, &LowerMemorySize, NULL);
+  if (Status == EFI_SUCCESS && LowerMemorySize > 0) {
+    return LowerMemorySize;
+  }
+
   //
   // CMOS 0x34/0x35 specifies the system memory above 16 MB.
   // * CMOS(0x35) is the high byte
@@ -722,7 +729,6 @@ QemuInitializeRam (
   // Determine total memory size available
   //
   LowerMemorySize = GetSystemMemorySizeBelow4gb ();
-  UpperMemorySize = GetSystemMemorySizeAbove4gb ();
 
   if (mBootMode == BOOT_ON_S3_RESUME) {
     //
@@ -769,8 +775,11 @@ QemuInitializeRam (
     // memory size read from the CMOS.
     //
     Status = ScanOrAdd64BitE820Ram (TRUE, NULL, NULL);
-    if (EFI_ERROR (Status) && UpperMemorySize != 0) {
-      AddMemoryBaseSizeHob (BASE_4GB, UpperMemorySize);
+    if (EFI_ERROR (Status)) {
+      UpperMemorySize = GetSystemMemorySizeAbove4gb ();
+      if (UpperMemorySize != 0) {
+        AddMemoryBaseSizeHob (BASE_4GB, UpperMemorySize);
+      }
     }
   }
 
-- 
2.31.1



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