From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 117DC412 for ; Sun, 11 Jun 2017 17:11:56 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-vk0-f51.google.com (mail-vk0-f51.google.com [209.85.213.51]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 375308E for ; Sun, 11 Jun 2017 17:11:55 +0000 (UTC) Received: by mail-vk0-f51.google.com with SMTP id 191so41282241vko.2 for ; Sun, 11 Jun 2017 10:11:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=jtimon-cc.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=wUTawrcNGEwnJBxEvCVbo68g7m5cvWPudDcsNpLRrks=; b=FAdM6NX059LSbwIqedTzTcnJCSTHlo3UV97Dt1lvr2MqS+OVK+9/TE2ei0rJEhm6sl 2Nys+1c5gcfmRDNgk/s8QI8L/xokhumKRIFilVeOxUHq4qhezaqGneFBKXYIXYLMQMoL MHehWIY2/ylSPSRfNgH+MYaevghV3YreA+hCBvFUxfic9juSzxrOJKBu7SIrylNx9ZA2 gKx9O53ujmZem8Igonc0XvNNInqYlXwfsRPNbODhW/WWY6wh2kIDVDcQUW1GfInl35lK aAsRn5OXBq9ca4dxZNNKKakx3RjTLRvrwTiuKr0jT2BdXU7/YlDNKHh81qHFx/4M77B/ /e0g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=wUTawrcNGEwnJBxEvCVbo68g7m5cvWPudDcsNpLRrks=; b=T8G+A+sscHf2WktSDN7zDrPOV0oaPRVg93MXbSrLlKixzNJB+En7UUgeZbYEISDQ6w 0hhXNnQlJpZwOlSrF7XSwe38zgc9DCx4aQinGCA1YIU+UsyKWFctREnLACGvB8ELmvfp U3y5OA+A/hxEhIEdPwXtCnbfe3yVij+ideVvjonW47PU0T5L3fnfUH0w7b1+GjPOzrWy zKDXW+A5V3Ky1vLzLUbs61N8qPrbnaD8oRGKateXSkyeMztFejtN0l9YCsUBG3hk0QWC LO91SD+uUdPmU0ShMx5+xnOA8kof5Og09TeEnoo0eBPCa3YSZFa5WtpSWYmFEtmXCTyS EFJA== X-Gm-Message-State: AODbwcB6wEv5ICKqNkP57POSsFb33VdwL26kStQ8W9GsWOUUG1NO0GHE XWvx+nwecW0N9rl3KaidIigFACsA7y3EABM= X-Received: by 10.31.9.204 with SMTP id 195mr26502878vkj.115.1497201114110; Sun, 11 Jun 2017 10:11:54 -0700 (PDT) MIME-Version: 1.0 Received: by 10.31.52.213 with HTTP; Sun, 11 Jun 2017 10:11:53 -0700 (PDT) In-Reply-To: References: From: =?UTF-8?B?Sm9yZ2UgVGltw7Nu?= Date: Sun, 11 Jun 2017 19:11:53 +0200 Message-ID: To: Jacob Eliosoff Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: Bitcoin Dev Subject: Re: [bitcoin-dev] The BIP148 chain split may be inevitable X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 11 Jun 2017 17:11:56 -0000 On Sat, Jun 10, 2017 at 8:04 PM, Jacob Eliosoff via bitcoin-dev wrote: > Just a quick follow-up on BIP91's prospects of avoiding a BIP148 chain > split, because I may have left an overly pessimistic impression - > > In short: the timing isn't as dire as I suggested, BUT unless concrete > progress on a plan starts taking shape, esp miner support, *the split is > indeed coming.* > > THE GOOD NEWS: several refinements have been noted which could get BIP91 (or > splitprotection, Segwit2x, etc) deployed faster: > - Of course the 80% threshold could just be reduced, eg to splitprotection's > 65% This still doesn't prevent the split if 45% or more of the hashrate keeps blocking segwit, so I don't see how this help. > - BIP91 nodes could start signaling on bit 1 the moment bit 4 reaches > lock-in, rather than waiting another period until it "activates". Miners could start signaling bit 1 today, before they use bip91 too and signal bit 4 in addition. But they aren't doing it, it seems they prefer to block segwit. I don't see why changing using bit 4 or reducing the threshold would change their mind. > THE BAD NEWS: no one should underestimate the steps that would need to be > completed by that deadline: > 1. Coordinate on a solution (BIP91, splitprotection, Segwit2x, BIP148 > itself, ...) > 2. Implement and test it > 3. Convince >50% of miners to run it [2] > 4. Miners upgrade to the new software and begin signaling > > In particular, #3: afaict a lot of convincing is still needed before miner > support for any of these reaches anything like 50%. (With the exception of > Segwit2x, but it has the additional handicap that it probably needs to > include deployable hard fork code, obviously ambitious in 1.5 months.) > Or you can replace this whole plan with the step 3, convincing miners to stop blocking segwit, upgrade to segwit capable code if they haven't already and signal bit 1 to activate it. If you don't get that, there's going to be a split. Unless bip148 is aborted in favor of bip149, which seems unlikely. If we had 51%+ of the hashrate currently signaling segwit, I believe there would be no problem convincing people to move from bip148 to bip91, but we don't have that. To me the lesson is not rushed deployments but bip8 and never commit the mistake of giving miners the ability to block changes again, like we did with csv and segwit, but using bip8 instead of bip9 from now on. > [1] See Saicere's comment: > https://github.com/btc1/bitcoin/pull/11#discussion_r121086886, and related > discussion at > https://github.com/btc1/bitcoin/pull/11#issuecomment-307330011. > > [2] Note that >50% need to run the *solution*, eg BIP91; old BIP141 nodes > signaling segwit support do *not* count, since they won't orphan non-bit-1 > blocks. The impending split isn't between nodes that support segwit vs > don't, but between those that reject non-segwit-supporting blocks vs don't. > > > On Fri, Jun 9, 2017 at 1:23 AM, Jacob Eliosoff > wrote: >> >> Ah, two corrections: >> 1. I meant to include an option c): of course >50% of hashpower running >> BIP148 by Aug 1 avoids a split. >> 2. More seriously, I misrepresented BIP148's logic: it doesn't require >> segwit *activation*, just orphans non-segwit-*signaling* (bit 1) blocks from >> Aug 1. >> >> I believe that means 80% of hashrate would need to be running BIP91 >> (signaling bit 4) by ~June 30 (so BIP91 locks in ~July 13, activates ~July >> 27), not "a few days ago" as I claimed. So, tight timing, but not >> impossible. >> >> Sorry about the errors. >> >> >> On Fri, Jun 9, 2017 at 12:40 AM, Jacob Eliosoff >> wrote: >>> >>> I've been trying to work out the expected interaction between James >>> Hilliard's BIP91 [1] (or splitprotection [2], or Segwit2x [3], which both >>> use variants of BIP91 activation) and the BIP148 UASF [4]. Some of this is >>> subtle so CORRECTIONS WELCOME, but my conclusions are: >>> 1. It's extremely unlikely BIP91-type logic can activate segwit in time >>> to avoid a BIP148 chain split. >>> 2. So, in practice all we can do is ensure the BIP148 split is as >>> painless as possible. >>> >>> REASONING: First, some dates. BIP148, whose deadline is already >>> deployed and thus unlikely to be postponed, starts orphaning non-segwit >>> blocks on midnight (GMT) the morning of August 1. Meanwhile, here are >>> Bitcoin's rough expected next four difficulty adjustment dates (they could >>> vary by ~1-3 days depending on block times, but it's unlikely to matter >>> here): >>> 1. June 17 >>> 2. June 30 >>> 3. July 13 >>> 4. July 27 >>> >>> If Segwit activates on adj date #5 or later (August), it will be too late >>> to avoid BIP148's split, which will have occurred the moment August began. >>> So, working backwards, and assuming we want compatibility with old BIP141 >>> nodes: >>> >>> - Segwit MUST activate by adj #4 (~July 27) >>> - Therefore segwit MUST be locked in by adj #3 (~July 13: this is >>> inflexible, since this logic is in already-deployed BIP141 nodes) >>> - Therefore, I *think* >50% of hashpower needs to be BIP91 miners, >>> signaling bit 1 and orphaning non-BIP91 (ie, BIP91's bit 4 must activate), >>> by adj #2 (June 30)? >>> - Therefore, as currently designed, BIP91 bit 4 must be locked in by adj >>> #1 (June 17) >>> - Therefore, >=80% of hashrate must start signaling BIP91's bit 4 by a >>> few days ago... >>> >>> There are ways parts of this could be sped up, eg, James' "rolling >>> 100-block lock-in periods" [5], to get BIP91 signaling bit 1 sooner. But to >>> be compatible with old BIP141 nodes, >50% of hashrate must be activated >>> BIP91 miners by ~June 30: there's no fudging that. >>> >>> So, it seems to me that to avoid the BIP148 split, one of two things >>> would have to happen: >>> a) 95% of hashrate start signaling bit 1 by ~June 30. Given current stat >>> is 32%, this would basically require magic. >>> b) BIP91 is deployed and >50% (80% or whatever) of hashrate is >>> *activated* BIP91 miners by ~June 30, ~3 weeks from now. Again, much too >>> soon. >>> >>> So, I think the BIP148 split is inevitable. I actually expect that few >>> parts of the ecosystem will join the fork, so disruption will be bearable. >>> But anyway let me know any flaws in the reasoning above. >>> >>> [1] https://github.com/bitcoin/bips/blob/master/bip-0091.mediawiki >>> [2] >>> https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-June/014508.html >>> [3] https://github.com/btc1/bitcoin/pull/11 >>> [4] https://github.com/bitcoin/bips/blob/master/bip-0148.mediawiki >>> [5] https://github.com/btc1/bitcoin/pull/6#issuecomment-305917729 >> >> > > > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >