Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751758AbbD2Vmj (ORCPT ); Wed, 29 Apr 2015 17:42:39 -0400 Received: from mail-la0-f46.google.com ([209.85.215.46]:36108 "EHLO mail-la0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750951AbbD2Vme (ORCPT ); Wed, 29 Apr 2015 17:42:34 -0400 MIME-Version: 1.0 In-Reply-To: <1430343554.2189.30.camel@HansenPartnership.com> References: <20150415131906.GC21491@kroah.com> <20150417134924.GB19794@kroah.com> <20150417143640.GB3671@codeblueprint.co.uk> <20150420144323.GA7261@kroah.com> <20150421075620.GA11000@kroah.com> <1429665679.2207.44.camel@HansenPartnership.com> <20150422132734.GB12062@redhat.com> <1429715913.2195.22.camel@HansenPartnership.com> <1429798187.2170.3.camel@HansenPartnership.com> <1429888575.2182.20.camel@HansenPartnership.com> <1430174136.2314.49.camel@HansenPartnership.com> <1430175112.2314.56.camel@HansenPartnership.com> <1430343304.2189.25.camel@HansenPartnership.com> <1430343554.2189.30.camel@HansenPartnership.com> From: Andy Lutomirski Date: Wed, 29 Apr 2015 14:42:12 -0700 Message-ID: Subject: Re: [PATCH v4 2/2] efi: an sysfs interface for user to update efi firmware To: James Bottomley Cc: "Kweh, Hock Leong" , Peter Jones , Greg Kroah-Hartman , Matt Fleming , Ming Lei , "Ong, Boon Leong" , LKML , "linux-efi@vger.kernel.org" , Sam Protsenko , Roy Franz , Borislav Petkov , Al Viro , Linux FS Devel Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3276 Lines: 80 On Wed, Apr 29, 2015 at 2:39 PM, James Bottomley wrote: > On Wed, 2015-04-29 at 14:36 -0700, Andy Lutomirski wrote: >> On Wed, Apr 29, 2015 at 2:35 PM, James Bottomley >> wrote: >> > On Wed, 2015-04-29 at 11:23 +0000, Kweh, Hock Leong wrote: >> >> I agree with James. Due to different people may have different needs. But >> >> from our side, we would just like to have a simple interface for us to upload >> >> the efi capsule and perform update. We do not have any use case or need >> >> to get info from QueryCapsuleUpdate(). Let me give a suggestion here: >> >> please allow me to focus on deliver this simple loading interface and >> >> upstream it. Then later whoever has the actual use case or needs on the ioctl >> >> implementation, he or she could enhance base on this simple loading interface. >> >> What do you guys think? >> >> >> >> Let me summarize the latest design idea: >> >> - No longer leverage on firmware class but use misc device >> >> - Do not use platform device but use device_create() >> >> - User just need to perform "cat file.bin > /sys/.../capsule_loader" in the shell >> >> - File operation functions include: open(), read(), write() and flush() >> >> - Perform mutex lock in open() then release the mutex in flush() for avoiding >> >> race condition / concurrent loading >> >> - Perform the capsule update and error return at flush() function >> >> >> >> Is there anything I missed? Any one still have concern with this idea? >> >> Thanks for providing the ideas as well as the review. >> > >> > I think that's pretty much it. >> > >> > Why don't you let me construct a straw man patch. It's going to be a >> > bit controversial because it involves adding flush operations to sysfs >> > and kernfs, slicing apart firmware_class.c to extract the transaction >> > handling stuff and creating an new efi update capsule file which makes >> > use of it. >> > >> > Once we have code, we at least have something more concrete to argue >> > over. >> >> Would it be worth checking whether busybox is also okay with it first? >> (Sorry to be a naysayer.) >> >> It would be a shame if we do all this to keep the userspace footprint >> light and then it doesn't work for non-coreutils userspace. > > I don't think so, because we can fix busybox if it's a problem. The > embedded people wanting this control the tool space, so they can decide > to use the fixed version. > > So yes, someone should check and fix busybox cat if broken, but no, it's > not a blocker. It's still a bit unfortunate that: #!/bin/sh cat "$1" >/sys/whatever if [ "$?" != "0" ]; then echo "It didn't work because" ... exit 1 fi echo "It worked! Go reboot if needed." exit 0 will only work sometimes. Will people really test this on their target implementation of cat? I agree that making this possible with just shell is nice, but I'm less happy about it if it'll be unreliable. --Andy -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/