Re: [PATCH V2 3/4] UefiCpuPkg/ResetVector: Add Main32 entry point in Main.asm

["Yao, Jiewen" <jiewen.yao@intel.com>]

Current OvmfPkg Reser vector is a mess (see my previous email).
I also compared the ResetVector code in UefiCpuPkg and OvmfPkg. There are already duplication/override.

I suggest we just drop UefiCpuPkg change, and focus on improving OvmfPkg.
If we need add something in UefiCpuPkg, let's copy the file to OvmfPkg and update there.

I really don't want to mess up UefiCpuPkg at this moment.
We can make a better architecture to share reset vector in virtual BIOS and physical BIOS later. But at this moment, let's finish the virtual BIOS architecture at first.

Thank you
Yao Jiewen

> -----Original Message-----
> From: Xu, Min M <min.m.xu@intel.com>
> Sent: Thursday, July 22, 2021 1:52 PM
> To: devel@edk2.groups.io
> Cc: Xu, Min M <min.m.xu@intel.com>; Dong, Eric <eric.dong@intel.com>; Ni,
> Ray <ray.ni@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>
> Subject: [PATCH V2 3/4] UefiCpuPkg/ResetVector: Add Main32 entry point in
> Main.asm
> 
> RFC: https://bugzilla.tianocore.org/show_bug.cgi?id=3429
> 
> In Tdx all CPUs "reset" to run on 32-bit protected mode with flat
> descriptor (paging disabled). Main32 entry point is added in
> UefiCpuPkg/ResetVector/Vtf0/Main.asm so that Main.asm can support
> the 32-bit protected mode.
> 
> Init32.asm is the 32-bit initialization code. It is a null stub in
> UefiCpuPkg. The actual initialization can be implemented in the platform
> (OvmfPkg/ResetVector/Ia32/Init32.asm is the example.)
> 
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Signed-off-by: Min Xu <min.m.xu@intel.com>
> ---
>  UefiCpuPkg/ResetVector/Vtf0/Ia32/Init32.asm | 13 +++++++++++++
>  UefiCpuPkg/ResetVector/Vtf0/Main.asm        | 14 ++++++++++++++
>  UefiCpuPkg/ResetVector/Vtf0/Vtf0.nasmb      |  2 +-
>  3 files changed, 28 insertions(+), 1 deletion(-)
>  create mode 100644 UefiCpuPkg/ResetVector/Vtf0/Ia32/Init32.asm
> 
> diff --git a/UefiCpuPkg/ResetVector/Vtf0/Ia32/Init32.asm
> b/UefiCpuPkg/ResetVector/Vtf0/Ia32/Init32.asm
> new file mode 100644
> index 000000000000..0cdae4a4a84a
> --- /dev/null
> +++ b/UefiCpuPkg/ResetVector/Vtf0/Ia32/Init32.asm
> @@ -0,0 +1,13 @@
> +;------------------------------------------------------------------------------
> +; @file
> +;   32-bit initialization code.
> +; Copyright (c) 2021, Intel Corporation. All rights reserved.<BR>
> +; SPDX-License-Identifier: BSD-2-Clause-Patent
> +;
> +;------------------------------------------------------------------------------
> +
> +BITS 32
> +
> +Init32:
> +    nop
> +    OneTimeCallRet Init32
> diff --git a/UefiCpuPkg/ResetVector/Vtf0/Main.asm
> b/UefiCpuPkg/ResetVector/Vtf0/Main.asm
> index 19d08482f831..4920c6937e1b 100644
> --- a/UefiCpuPkg/ResetVector/Vtf0/Main.asm
> +++ b/UefiCpuPkg/ResetVector/Vtf0/Main.asm
> @@ -36,6 +36,20 @@ Main16:
> 
>  BITS    32
> 
> +%ifdef ARCH_X64
> +
> +    jmp SearchBfv
> +
> +;
> +; Entry point of Main32
> +;
> +Main32:
> +
> +    OneTimeCall Init32
> +
> +%endif
> +
> +SearchBfv:
>      ;
>      ; Search for the Boot Firmware Volume (BFV)
>      ;
> diff --git a/UefiCpuPkg/ResetVector/Vtf0/Vtf0.nasmb
> b/UefiCpuPkg/ResetVector/Vtf0/Vtf0.nasmb
> index 493738c79c1c..6493b9863c48 100644
> --- a/UefiCpuPkg/ResetVector/Vtf0/Vtf0.nasmb
> +++ b/UefiCpuPkg/ResetVector/Vtf0/Vtf0.nasmb
> @@ -51,7 +51,7 @@
>  %include "Ia32/SearchForSecEntry.asm"
> 
>  %ifdef ARCH_X64
> -%include "Ia32/Flat32ToFlat64.asm"
> +%include "Ia32/Init32.asm"
>  %include "Ia32/PageTables64.asm"
>  %endif
> 
> --
> 2.29.2.windows.2