Re: [bitcoin-dev] CLTV/CSV/etc. deployment considerations due to XT/Not-BitcoinXT miners

From: Mark Friedenbach <mark@friedenbach•org>
To: jl2012@xbt•hk
Cc: Bitcoin Dev <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] CLTV/CSV/etc. deployment considerations due to XT/Not-BitcoinXT miners
Date: Thu, 20 Aug 2015 10:42:45 -0700	[thread overview]
Message-ID: <CAOG=w-tA0Rme_geadjaZCP4QRYb2T0y7PGCZ-QbjGVt2H+=z=w@mail.gmail.com> (raw)
In-Reply-To: <c20a83f511d7023f9cdd2df4713cddf9@xbt.hk>

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No, the nVersion would be >= 4, so that we don't waste any version values.

On Thu, Aug 20, 2015 at 10:32 AM, jl2012 via bitcoin-dev <
bitcoin-dev@lists•linuxfoundation.org> wrote:

> Peter Todd via bitcoin-dev 於 2015-08-19 01:50 寫到:
>
>
>>
>> 2) nVersion mask, with IsSuperMajority()
>>
>> In this option the nVersion bits set by XT/Not-Bitcoin-XT miners would
>> be masked away, prior to applying standard IsSuperMajority() logic:
>>
>>     block.nVersion & ~0x20000007
>>
>> This means that CLTV/CSV/etc. miners running Bitcoin Core would create
>> blocks with nVersion=8, 0b1000. From the perspective of the
>> CLTV/CSV/etc.  IsSuperMajority() test, XT/Not-Bitcoin-XT miners would be
>> advertising blocks that do not trigger the soft-fork.
>>
>> For the perpose of soft-fork warnings, the highest known version can
>> remain nVersion=8, which is triggered by both XT/Not-Bitcoin-XT blocks
>> as well as a future nVersion bits implementation. Equally,
>> XT/Not-Bitcoin-XT soft-fork warnings will be triggered, by having an
>> unknown bit set.
>>
>> When nVersion bits is implemented by the Bitcoin protocol, the plan of
>> setting the high bits to 0b001 still works. The three lowest bits will
>> be unusable for some time, but will be eventually recoverable as
>> XT/Not-Bitcoin-XT mining ceases.
>>
>> Equally, further IsSuperMajority() softforks can be accomplished with
>> the same masking technique.
>>
>> This option does complicate the XT-coin protocol implementation in the
>> future. But that's their problem, and anyway, the maintainers
>> (Hearn/Andresen) has strenuously argued(5) against the use of soft-forks
>> and/or appear to be in favor of a more centralized mandatory update
>> schedule.(6)
>>
>>
> If you are going to mask bits, would you consider to mask all bits except
> the 4th bit? So other fork proposals may use other bits for voting
> concurrently.
>
> And as I understand, the masking is applied only during the voting stage?
> After the softfork is fully enforced with 95% support, the nVersion will be
> simply >=8, without any masking?
>
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