From: Btc Drak <btcdrak@gmail•com>
To: Tier Nolan <tier.nolan@gmail•com>
Cc: Bitcoin Dev <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] CLTV/CSV/etc. deployment considerations due to XT/Not-BitcoinXT miners
Date: Wed, 19 Aug 2015 18:25:20 +0100 [thread overview]
Message-ID: <CADJgMzsvAfJnW1DDD6t3qkBcQRLb4HMqG27k51LhXJqxC6-z4g@mail.gmail.com> (raw)
In-Reply-To: <CAE-z3OVAJcnFn21F9QTGCf=NZrLQ9hAtj_tqSCboQGCfFSvq=Q@mail.gmail.com>
On Wed, Aug 19, 2015 at 2:24 PM, Tier Nolan via bitcoin-dev
<bitcoin-dev@lists•linuxfoundation.org> wrote:
> On Wed, Aug 19, 2015 at 2:15 PM, Btc Drak via bitcoin-dev <bitcoin-dev@lists•linuxfoundation.org> wrote:
>> What problem am I missing if we just mask of the offending bits. For my own project which uses auxpow (and thus has weird nVersion), I also used the bitmasking method to get rid of auxpow version bits before making the standard integer comparisons to deploy BIP66 using IsSuperMajority():
>>
>> if ((block.nVersion & 0xff) >= 4 && CBlockIndex::IsSuperMajority(...)) { //...}
>
> What if version number 257 is used in the future? That would appear to be a version 1 block and fail the test.
To clarify this is the code example for how the same problem occurs
with auxpow bits when running a an IsSuperMajority() softfork and how
it's solved in that instance.
In our case for Bitcoin Core, option 2 we use nVersion=8, apply a
bitmask of 0xdffffff8 thus:
if ((block.nVersion & ~0x20000007) >= 4 &&
CBlockIndex::IsSuperMajority(...)) { //...}
With nVersion=8, but using comparison >=4 allows us to recover the
bit later, assuming we want it (otherwise we use version >=8).
This should, unless I am missing something, be forward compatible with
future softforks. My understanding was if "versionbits softfork" code
is not ready by the time we're ready for the deployment,
IsSuperMajority() would be acceptable; and this is how we could deploy
it in the wake of the XT developers' carelessness.
next prev parent reply other threads:[~2015-08-19 17:25 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-19 5:50 Peter Todd
2015-08-19 6:10 ` Mark Friedenbach
2015-08-19 9:34 ` Jorge Timón
2015-08-19 10:20 ` Btc Drak
2015-08-19 10:31 ` Jorge Timón
2015-08-19 13:15 ` Btc Drak
2015-08-19 13:24 ` Tier Nolan
2015-08-19 17:25 ` Btc Drak [this message]
2015-08-19 18:17 ` Tier Nolan
2015-08-19 12:36 ` Matt Corallo
2015-08-19 13:22 ` Tier Nolan
2015-08-19 14:01 ` Jeff Garzik
2015-08-19 16:32 ` Mark Friedenbach
2015-08-19 21:03 ` Peter Todd
2015-08-20 17:32 ` jl2012
2015-08-20 17:42 ` Mark Friedenbach
2015-08-27 22:11 ` Btc Drak
-- strict thread matches above, loose matches on Subject: below --
2015-08-18 1:22 [bitcoin-dev] BIP: Using Median time-past as endpoint for locktime calculations Thomas Kerin
2015-08-19 1:04 ` Peter Todd
2015-08-19 1:08 ` Mark Friedenbach
2015-08-21 11:13 ` Thomas Kerin
2015-08-22 0:57 ` Peter Todd
2015-08-27 22:08 ` Btc Drak
2015-08-27 23:19 ` Peter Todd
2015-08-28 15:27 ` jl2012
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