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Date:   Tue, 19 Apr 2022 07:24:43 -0700
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To:     Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        Kai Huang <kai.huang@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        Hans de Goede <hdegoede@redhat.com>,
        Mark Gross <mgross@linux.intel.com>
Cc:     "H . Peter Anvin" <hpa@zytor.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Andi Kleen <ak@linux.intel.com>, linux-kernel@vger.kernel.org,
        platform-driver-x86@vger.kernel.org
References: <20220415220109.282834-1-sathyanarayanan.kuppuswamy@linux.intel.com>
 <20220415220109.282834-5-sathyanarayanan.kuppuswamy@linux.intel.com>
 <bd83067542a3519ee4c91f9d50e9bd4fac27e4bb.camel@intel.com>
 <975b5050-2108-9ace-cc71-46f17db0a731@intel.com>
 <4875ea9c-593a-e669-889a-1e809a50a570@linux.intel.com>
From:   Dave Hansen <dave.hansen@intel.com>
Subject: Re: [PATCH v3 4/4] platform/x86: intel_tdx_attest: Add TDX Guest
 attestation interface driver
In-Reply-To: <4875ea9c-593a-e669-889a-1e809a50a570@linux.intel.com>
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On 4/19/22 07:19, Sathyanarayanan Kuppuswamy wrote:
> On 4/19/22 7:13 AM, Dave Hansen wrote:
>>> >From this perspective, I am not sure what's the value of having a
>>> dedicated
>>> INTEL_TDX_ATTESTATION Kconfig.  The attestation support code should
>>> be turned on
>>> unconditionally when CONFIG_INTEL_TDX_GUEST is on.  The code can also
>>> be just
>>> under arch/x86/coco/tdx/ I guess?
>> How much code are we talking about?  What's the difference in the size
>> of the binaries with this compiled in?
> 
> Current driver size is ~300 lines. It adds ~500 bytes to the kernel
> binary if it is built-in.

That doesn't sound like good use of a Kconfig option to me.  Just
explain in the cover letter:

	Any distribution enabling TDX is also expected to need
	attestation.  The compiled size is quite small (500 bytes).