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Date: Tue, 9 May 2023 16:41:58 +0200
From: "Gerd Hoffmann" <kraxel@redhat.com>
To: devel@edk2.groups.io, jiaxin.wu@intel.com
Cc: Eric Dong <eric.dong@intel.com>, Ray Ni <ray.ni@intel.com>, 
	Zeng Star <star.zeng@intel.com>, Rahul Kumar <rahul1.kumar@intel.com>
Subject: Re: [edk2-devel] [PATCH v1 2/3] UefiCpuPkg/CpuMpPei: Enable PAE page table if CR0.PG is not set
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References: <20230509102253.16632-1-jiaxin.wu@intel.com>
 <20230509102253.16632-3-jiaxin.wu@intel.com>
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  Hi,

> +    //
> +    // Check CPU runs in 32bit mode.
> +    //
> +    MsrEfer.Uint64 = AsmReadMsr64 (MSR_CORE_IA32_EFER);
> +    if (MsrEfer.Bits.LMA == 1) {

Checking this at runtime is pointless.  32bit code would simply
not work in long mode and visa versa.

take care,
  Gerd