From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4CC6CC28CBE for ; Fri, 28 Sep 2018 16:28:54 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AC7AA2064E for ; Fri, 28 Sep 2018 16:28:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AC7AA2064E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 42MHDg4Dr1zF3L1 for ; Sat, 29 Sep 2018 02:28:51 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: lists.ozlabs.org; spf=permerror (mailfrom) smtp.mailfrom=kernel.crashing.org (client-ip=63.228.1.57; helo=gate.crashing.org; envelope-from=segher@kernel.crashing.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 42MHBf4DmYzF381 for ; Sat, 29 Sep 2018 02:27:06 +1000 (AEST) Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id w8SGQShG028469; Fri, 28 Sep 2018 11:26:28 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id w8SGQQr0028459; Fri, 28 Sep 2018 11:26:26 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Fri, 28 Sep 2018 11:26:25 -0500 From: Segher Boessenkool To: Michael Ellerman Subject: Re: [PATCH v4 1/2] powerpc/32: add stack protector support Message-ID: <20180928162625.GT23155@gate.crashing.org> References: <20180926191615.GO23155@gate.crashing.org> <220fbef8-429c-9485-d10e-c1eaa989918d@c-s.fr> <20180927074525.GQ23155@gate.crashing.org> <28451b6a-e302-691e-ee28-16521997fb07@c-s.fr> <8736ttu6fs.fsf@concordia.ellerman.id.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8736ttu6fs.fsf@concordia.ellerman.id.au> User-Agent: Mutt/1.4.2.3i X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paul Mackerras , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Fri, Sep 28, 2018 at 10:56:07PM +1000, Michael Ellerman wrote: > The problem of low entropy at boot on systems without a good hardware > source is sort of unsolvable. > > As you say it's up to the core kernel/random code, we shouldn't be > trying to do anything tricky in the arch code. > > You don't want your system to take 3 hours to boot because it's waiting > for entropy for the stack canary. > > If we can update the canary later once the entropy pool is setup that > would be ideal. Yup, I agree with all that. But we should *also* not say "oh, there may be cases where we cannot do the right thing, so just do not even try, ever, anywhere". Segher