Re: [edk2-devel] [PATCH] MdeModulePkg: Disambiguate the meaning of PcdDxeIplSwitchToLongMode

["Zhiguang Liu" <zhiguang.liu@intel.com>]

Hi Liming and Jian,

What do you think about this patch?

Thanks
Zhiguang

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of
> Zhiguang Liu
> Sent: Monday, January 9, 2023 11:34 AM
> To: devel@edk2.groups.io
> Cc: Liu, Zhiguang <zhiguang.liu@intel.com>; Wang, Jian J
> <jian.j.wang@intel.com>; Gao, Liming <gaoliming@byosoft.com.cn>; Ni, Ray
> <ray.ni@intel.com>
> Subject: [edk2-devel] [PATCH] MdeModulePkg: Disambiguate the meaning
> of PcdDxeIplSwitchToLongMode
> 
> Literally, the meaning of PcdDxeIplSwitchToLongMode is clear, indicating
> whether need switch to long mode when loading DxeCore.
> However, the comments in dec are confusing for the case where PEI core
> and DXE core are both in 64-bit. This patch makes it clear.
> PcdDxeIplSwitchToLongMode is true only when PEI core is 32-bit, and switch
> to long mode to load 64-bit DXE core. In other cases, this PCD is false.
> This also aligns with current usage in OvmfPkg.
> 
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Liming Gao <gaoliming@byosoft.com.cn>
> Cc: Ray Ni <ray.ni@intel.com>
> Signed-off-by: Zhiguang Liu <zhiguang.liu@intel.com>
> ---
>  MdeModulePkg/MdeModulePkg.dec | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/MdeModulePkg/MdeModulePkg.dec
> b/MdeModulePkg/MdeModulePkg.dec index be5e829ca9..5e4535e353
> 100644
> --- a/MdeModulePkg/MdeModulePkg.dec
> +++ b/MdeModulePkg/MdeModulePkg.dec
> @@ -922,10 +922,8 @@
> 
>  [PcdsFeatureFlag.IA32, PcdsFeatureFlag.X64]
>    ## Indicates if DxeIpl should switch to long mode to enter DXE phase.
> -  #  It is assumed that 64-bit DxeCore is built in firmware if it is true;
> otherwise 32-bit DxeCore
> -  #  is built in firmware.<BR><BR>
>    #   TRUE  - DxeIpl will load a 64-bit DxeCore and switch to long mode to hand
> over to DxeCore.<BR>
> -  #   FALSE - DxeIpl will load a 32-bit DxeCore and perform stack switch to
> hand over to DxeCore.<BR>
> +  #   FALSE - DxeIpl will load a 32-bit or 64-bit DxeCore and perform stack
> switch to hand over to DxeCore.<BR>
>    # @Prompt DxeIpl switch to long mode.
> 
> gEfiMdeModulePkgTokenSpaceGuid.PcdDxeIplSwitchToLongMode|TRUE|B
> OOLEAN|0x0001003b
> 
> --
> 2.31.1.windows.1
> 
> 
> 
> 
>