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Date:   Mon, 10 Aug 2020 16:48:37 -0700
From:   Sean Christopherson <sean.j.christopherson@intel.com>
To:     Andy Lutomirski <luto@kernel.org>
Cc:     Nathaniel McCallum <npmccallum@redhat.com>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
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        Jethro Beekman <jethro@fortanix.com>,
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        Thomas Gleixner <tglx@linutronix.de>, yaozhangx@google.com
Subject: Re: [PATCH v36 21/24] x86/vdso: Implement a vDSO for Intel SGX
 enclave call
Message-ID: <20200810234837.GH14724@linux.intel.com>
References: <20200716135303.276442-1-jarkko.sakkinen@linux.intel.com>
 <20200716135303.276442-22-jarkko.sakkinen@linux.intel.com>
 <CAOASepOqRfUafSv_qjUv-jW_6n8G7kZ9yh-2z_Z9sjL_2zqNCg@mail.gmail.com>
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On Mon, Aug 10, 2020 at 04:08:46PM -0700, Andy Lutomirski wrote:
> What am I missing?  I still don't really understand why we are
> supporting this mechanism at all.  Just the asm code to invoke the
> callback seems to be about half of the entire function.

Because the Intel SDK (and other SDKs?) wants to use the host stack to pass
parameters out of the enclave.