[bitcoin-dev] Miners forced to run non-core code in order to get segwit activated

Tue Jun 20 22:57:34 UTC 2017

I could be wrong, but the latest BIP91 implementation (also included in
Segwit2x) cuts the activation period to 336 blocks (2.33 days).  (This has
been updated at
https://github.com/bitcoin/bips/blob/master/bip-0091.mediawiki.)  So if 80%
of hashpower is actually running that code and signaling on bit 4 by July
25 or so, then those 80+% will start orphaning non-bit-1 blocks before Aug
1, and we avoid a split.

There may still be a few non-bit-1 blocks that get orphaned after Aug 1,
because they're mined by old BIP141 nodes.  But it seems like very few
miners won't be signaling either Segwit2x *or* BIP141 by then...

Make sense?

On Tue, Jun 20, 2017 at 6:48 PM, Mark Friedenbach <mark at friedenbach.org>
wrote:

> Why do you say activation by August 1st is likely? That would require an
> entire difficulty adjustment period with >=95% bit1 signaling. That seems a
> tall order to organize in the scant few weeks remaining.
>
> On Jun 20, 2017, at 3:29 PM, Jacob Eliosoff via bitcoin-dev <
> bitcoin-dev at lists.linuxfoundation.org> wrote:
>
> If segwit is activated before Aug 1, as now seems likely, there will be no
> split that day.  But if activation is via Segwit2x (also likely), and at
> least some nodes do & some don't follow through with the HF 3mo later
> (again, likely), agreed w/ Greg that *then* we'll see a split - probably in
> Sep/Oct.  How those two chains will match up and how the split will play
> out is anyone's guess...
>
>
>
> On Jun 20, 2017 6:16 PM, "Hampus Sjöberg via bitcoin-dev" <
> bitcoin-dev at lists.linuxfoundation.org> wrote:
>
> > Ironically, it looks like most of the segwit2x signaling miners are
> > faking it (because they're not signaling segwit which it requires).
> > It'll be unfortunate if some aren't faking it and start orphaning
> > their own blocks because they are failing to signal segwit.
>
> Well, they're doing some kind of "pre-signaling" in the coinbase at the
> moment, because the segwit2x project is still in alpha-phase according to
> the timeline. They're just showing commitment.
> I'm sure they will begin signaling on version bit 4/BIP91 as well as
> actually running a segwit2x node when the time comes.
>
>
> > As far as prevent a chain split goes, all those things
> > (148/91/segwit2x(per today)) effectively guarantee a chainsplit-- so I
> > don't think that holds.
>
> Segwit2x/BIP91/BIP148 will orphan miners that do not run a Segwit2x (or
> BIP148) node, because they wouldn't have the new consensus rule of
> requiring all blocks to signal for segwit.
> I don't believe there would be any long lasting chainsplit though (because
> of the ~80% hashrate support on segwit2x), perhaps 2-3 blocks if we get
> unlucky.
>
> Hampus
>
> 2017-06-20 23:49 GMT+02:00 Gregory Maxwell via bitcoin-dev <
> bitcoin-dev at lists.linuxfoundation.org>:
>
>> On Tue, Jun 20, 2017 at 3:44 PM, Erik Aronesty via bitcoin-dev
>> <bitcoin-dev at lists.linuxfoundation.org> wrote:
>> > Because a large percentage of miners are indifferent, right now miners
>> have
>> > to choose between BIP148 and Segwit2x if they want to activate Segwit.
>>
>> Miners can simply continuing signaling segwit, which will leave them
>> at least soft-fork compatible with BIP148 and BIP91 (and god knows
>> what "segwit2x" is since they keep changing the actual definition and
>> do not have a specification; but last I saw the near-term behavior the
>> same as BIP91 but with a radically reduced activation window, so the
>> story would be the same there in the near term).
>>
>> Ironically, it looks like most of the segwit2x signaling miners are
>> faking it (because they're not signaling segwit which it requires).
>> It'll be unfortunate if some aren't faking it and start orphaning
>> their own blocks because they are failing to signal segwit.
>>
>> I don't think the rejection of segwit2x from Bitcoin's developers
>> could be any more resolute than what we've already seen:
>> https://en.bitcoin.it/wiki/Segwit_support
>>
>> On Tue, Jun 20, 2017 at 5:22 PM, Mark Friedenbach via bitcoin-dev
>> <bitcoin-dev at lists.linuxfoundation.org> wrote:
>> > I think it is very naïve to assume that any shift would be temporary.
>> > We have a hard enough time getting miners to proactively upgrade to
>> > recent versions of the reference bitcoin daemon. If miners interpret
>> > the situation as being forced to run non-reference software in order
>> > to prevent a chain split because a lack of support from Bitcoin Core,
>> > that could be a one-way street.
>>
>> I think this is somewhat naive and sounds a lot like the repeat of the
>> previously debunked "XT" and "Classic" hysteria.
>>
>> There is a reason that segwit2x is pretty much unanimously rejected by
>> the technical community.  And just like with XT/Classic/Unlimited
>> you'll continue to see a strong correlation with people who are
>> unwilling and unable to keep updating the software at an acceptable
>> level of quality-- esp. because the very founding on their fork is
>> predicated on discarding those properties.
>>
>> If miners want to go off and create an altcoin-- welp, thats something
>> they can always do,  and nothing about that will force anyone to go
>> along with it.
>>
>> As far as prevent a chain split goes, all those things
>> (148/91/segwit2x(per today)) effectively guarantee a chainsplit-- so I
>> don't think that holds.
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