On 1/26/24 08:29, Gerd Hoffmann wrote:
Neat when doing ResetVector coding.
Incompatible with TDX and SEV, therefore not enabled by default.
Signed-off-by: Gerd Hoffmann <kra...@redhat.com>
Acked-by: Tom Lendacky <thomas.lenda...@amd.com>
---
OvmfPkg/ResetVector/QemuDebugCon.asm | 35 +++++++++++++++++++++++++++
OvmfPkg/ResetVector/ResetVector.nasmb | 4 +++
2 files changed, 39 insertions(+)
create mode 100644 OvmfPkg/ResetVector/QemuDebugCon.asm
diff --git a/OvmfPkg/ResetVector/QemuDebugCon.asm
b/OvmfPkg/ResetVector/QemuDebugCon.asm
new file mode 100644
index 000000000000..e385ca1be83a
--- /dev/null
+++ b/OvmfPkg/ResetVector/QemuDebugCon.asm
@@ -0,0 +1,35 @@
+;------------------------------------------------------------------------------
+; @file
+; qemu debug console support macros (based on serial port macros)
+;
+; Copyright (c) 2008 - 2018, Intel Corporation. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+;------------------------------------------------------------------------------
+
+%macro debugShowCharacter 1
+ mov dx, 0x402
+ mov al, %1
+ out dx, al
+%endmacro
+
+%macro debugShowHexDigit 1
+ %if (%1 < 0xa)
+ debugShowCharacter BYTE ('0' + (%1))
+ %else
+ debugShowCharacter BYTE ('a' + ((%1) - 0xa))
+ %endif
+%endmacro
+
+%macro debugShowPostCode 1
+ debugShowHexDigit (((%1) >> 4) & 0xf)
+ debugShowHexDigit ((%1) & 0xf)
+ debugShowCharacter `\r`
+ debugShowCharacter `\n`
+%endmacro
+
+BITS 16
+
+%macro debugInitialize 0
+ ; not required
+%endmacro
diff --git a/OvmfPkg/ResetVector/ResetVector.nasmb
b/OvmfPkg/ResetVector/ResetVector.nasmb
index 5832aaa8abf7..69ce43ef6a96 100644
--- a/OvmfPkg/ResetVector/ResetVector.nasmb
+++ b/OvmfPkg/ResetVector/ResetVector.nasmb
@@ -40,6 +40,10 @@
%include "Port80Debug.asm"
%elifdef DEBUG_SERIAL
%include "SerialDebug.asm"
+%elif 0
+; Set ^ this to 1 to enable postcodes on the qemu debug console.
+; Disabled by default because it is incompatible with SEV and TDX.
+ %include "QemuDebugCon.asm"
%else
%include "DebugDisabled.asm"
%endif
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