From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [RFC] ARM VM System Sepcification
Date: Sat, 22 Mar 2014 09:08:37 +0100
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Cc: cross-distro@lists.linaro.org, Ian Campbell <ian.campbell@citrix.com>,
 "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
 Michael Casadevall <Michael.casadevall@linaro.org>,
 Peter Maydell <peter.maydell@linaro.org>, Jordan Justen <jljusten@gmail.com>,
 Rob Herring <rob.herring@linaro.org>, Leif Lindholm <leif.lindholm@linaro.org>,
 xen-devel@lists.xen.org, Robie Basak <robie.basak@canonical.com>,
 Stefano Stabellini <stefano.stabellini@citrix.com>,
 "marc.zyngier@arm.com" <marc.zyngier@arm.com>,
 Laszlo Ersek <lersek@redhat.com>,
 "kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
 "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>
To: Christoffer Dall <christoffer.dall@linaro.org>,
 Grant Likely <grant.likely@linaro.org>
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Il 22/03/2014 03:29, Christoffer Dall ha scritto:
> 1. Simply mandate that VM implementations support persistent variables
>    for their UEFI implementation - with whatever constraints that may
>    put on higher level tools.
>
> 2. Require that OSes shipped as part of compliant VM images make no
>    assumption that changes to the UEFI environment will be stored.
>
> I feel that option number two will break in all sorts of cases, just
> like Grant stated above, and it is fundamentally not practical; if a
> distribution ships Linux with a UEFI stub that expects to be able to do
> something, distributions must modify Linux to conform to this spec.  I
> think imagining that this spec controls how UEFI support in Linux/Grub
> is done in general would be overreaching.  Additionally, Michael brought
> up the fact that it would be non-UEFI compliant.

OSes are already able to cope with loss of changes to UEFI environment 
are stored, because losing persistent variables is what happens if you 
copy an image to a new hard disk.

Asking implementations for support of persistent variables is a good 
idea; however, independent of what is in the spec, OSes should not 
expect that users will enable that support---most of them won't.

Paolo