From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matt Fleming Subject: Re: [PATCH 5/5] efi: Capsule update support and pstore backend Date: Thu, 17 Oct 2013 13:14:01 +0100 Message-ID: <20131017121401.GG10834@console-pimps.org> References: <1381931460-6999-1-git-send-email-matt@console-pimps.org> <1381931460-6999-6-git-send-email-matt@console-pimps.org> <20131016201416.GG7456@tassilo.jf.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20131016201416.GG7456@tassilo.jf.intel.com> Sender: linux-kernel-owner@vger.kernel.org To: Andi Kleen Cc: linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, Tony Luck , Seiji Aguchi , x86@kernel.org, Matt Fleming List-Id: linux-efi@vger.kernel.org On Wed, 16 Oct, at 01:14:16PM, Andi Kleen wrote: > > + It should be noted that enabling this opton will pass a capsule > > + to the firmware on every boot. Some firmware will not allow a > > + user to enter the BIOS setup when a capsule has been registered > > + on the previous boot. > > That sounds like a problem. Can this be fixed to only do it on demand? Incorporating something along the lines of, echo 1 > /sys/kernel/debug/capsule_enable would fix this. Assuming that's the kind of thing Matthew had in mind. > > + > > + Many EFI machines have buggy implementations of the UpdateCapsule() > > + runtime service. This option will enable code that may not function > > + correctly with your firmware. > > Do we need white/black lists? > > Controlling such things form CONFIG is not very good. We have, so far, avoided creating black/white lists in any of the EFI code and because this is an optional debug feature and is in no way required for a user's machine to boot, I'm not sure how much value there would be in trying to maintain such a list. On the other hand, the case could be made for failing more gracefully if we discover the QueryCapsuleCapabilities()/UpdateCapsule() runtime services are broken when enabling this feature, i.e. through gratuitous use of FW_BUG. -- Matt Fleming, Intel Open Source Technology Center