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Donenfeld" To: Peter Maydell Cc: Alex =?utf-8?Q?Benn=C3=A9e?= , qemu-devel@nongnu.org Subject: Re: [PATCH] hw/arm/virt: dt: add rng-seed property Message-ID: References: <20220627160734.749861-1-Jason@zx2c4.com> <878rpfixfh.fsf@linaro.org> <87r137h49s.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Received-SPF: pass client-ip=2604:1380:4641:c500::1; envelope-from=SRS0=bCe9=XF=zx2c4.com=Jason@kernel.org; helo=dfw.source.kernel.org X-Spam_score_int: -67 X-Spam_score: -6.8 X-Spam_bar: ------ X-Spam_report: (-6.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=0.249, RCVD_IN_DNSWL_HI=-5, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01, T_SPF_HELO_TEMPERROR=0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Jun 30, 2022 at 10:15:29AM +0100, Peter Maydell wrote: > On Wed, 29 Jun 2022 at 16:56, Jason A. Donenfeld wrote: > > On Wed, Jun 29, 2022 at 04:24:20PM +0100, Alex Bennée wrote: > > > Given the use case for the dtb-kaslr-seed knob I wonder if we should > > > have a common property and deprecate the kaslr one? As of this patch > > > existing workflows will break until command lines are updated to suppress > > > the second source of randomness. > > > > > > Maybe it would be better to have a single a new property > > > (dtb-rng-seeds?) which suppresses both dtb entries and make > > > dtb-kaslr-seed an alias and mark it as deprecated. > > > > No, I don't think so. If anything, I'll try to get rid of kaslr-seed > > upstream at some point if that makes sense. But until that happens -- > > that is, until I have the conversations with people who added these and > > care about their semantics -- assume that there's granularity for some > > good reason. No need to put the cart before the horse. > > > > This is a simple patch doing a simple thing in exactly the way that > > things are already being done. I really don't want to do much more than > > that here. If you want to bikeshed it further, send a follow up patch. > > It's adding a command line option, though. Those we have to get > right the first time, because for QEMU they're kind of like ABI > to our users. We *can* clean them up if we find we've made a mistake, > but we have to go through a multi-release deprecation process to do it, > so it's much less effort overall to make sure we have the command line > syntax right to start with. > > If there's a good use case for the two seeds to be separately > controllable, that's fine. But I'd rather we find that out for > certain before we put a second control knob and make all our > users with workflows where they want non-random dtb blobs find > out about it and flip it. Okay. Do you want me to just make this controllable by dtb-kaslr-seed for now, then, and we can rename that in a follow-up commit? I'll send a patch for that. Jason