Re: [edk2-devel] [PATCH v3 1/1] OvmfPkg/ResetVector: send post codes to qemu debug console

["Laszlo Ersek" <lersek@redhat.com>]

On 1/29/24 13:29, Gerd Hoffmann wrote:
> Neat when doing ResetVector coding.
> Incompatible with TDX and SEV, therefore not enabled by default.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
> Acked-by: Erdem Aktas <erdemaktas@google.com>
> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
> ---
>  OvmfPkg/ResetVector/QemuDebugCon.asm  | 36 +++++++++++++++++++++++++++
>  OvmfPkg/ResetVector/ResetVector.nasmb |  4 +++
>  2 files changed, 40 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..8729fc2ffc0a
> --- /dev/null
> +++ b/OvmfPkg/ResetVector/QemuDebugCon.asm
> @@ -0,0 +1,36 @@
> +;------------------------------------------------------------------------------
> +; @file
> +; qemu debug console support macros (based on serial port macros)
> +;
> +; Copyright (c) 2008 - 2018, Intel Corporation. All rights reserved.<BR>
> +; Copyright (c) 2024, Red Hat, Inc.<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

https://github.com/tianocore/edk2/pull/5319; commit 98c7cb3be73d.

I replaced the "SEV" reference with "SEV-ES/SEV-SNP" in the comment.

Thanks!
Laszlo



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