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Date:   Fri, 6 Mar 2020 20:58:04 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To:     Sean Christopherson <sean.j.christopherson@intel.com>
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        Suresh Siddha <suresh.b.siddha@intel.com>,
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        Chunyang Hui <sanqian.hcy@antfin.com>
Subject: Re: [PATCH v28 11/22] x86/sgx: Linux Enclave Driver
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On Thu, Mar 05, 2020 at 09:40:15AM -0800, Sean Christopherson wrote:
> Would it make sense to add reserved fields to the structs so that new
> features can be added in a backwards compatible way?  E.g. if we want to
> allow userspace to control the backing store by passing in a file
> descriptor ENCLAVE_CREATE.

It would not really be a huge win even if you did that since old
software would not be aware of the new fields. Sounds somewhat
messy to me.

Even a new ioctl later on is in my opinion always a better option
than reserved fields when you add ioctl's.

/Jarkko