From: Melvin Carvalho <melvincarvalho@gmail.com>
To: Sjors Provoost <sjors@sprovoost.nl>
Cc: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
Subject: Re: [bitcoindev] Bip54: add sequence, timestamp (and version) to GBT
Date: Tue, 10 Feb 2026 06:12:55 +0100 [thread overview]
Message-ID: <CAKaEYh+cjFBx42vhag3dd1zF0QFbgXHPL0fBUDFcA4aZY63EvQ@mail.gmail.com> (raw)
In-Reply-To: <1A3B8BFA-41A6-4D0F-BBE6-E791F9785A5E@sprovoost.nl>
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po 9. 2. 2026 v 20:46 odesílatel Sjors Provoost <sjors@sprovoost.nl> napsal:
> Dear list,
>
> BIP54 proposes constraining the coinbase transaction nLockTime and
> nSequence fields. Although it's not that difficult for pools to adjust
> their software to set the correct values based on the known block height,
> it seems appropriate and convenient to have node software provide these
> values via the getblocktemplate RPC.
>
> SegWit had its own BIP for adding fields, but that was a significantly
> bigger lift. My preference would be to just extend BIP54, as I've done
> below.
>
> Feel free to respond on the list or here:
> https://github.com/bitcoin/bips/pull/2097
BIP54’s consensus fixes are currently uncontroversial.
Bundling new getblocktemplate additions into it changes that and expands
the policy surface. Those additions should be specified separately, where
they belong.
>
>
> Current version of BIP54:
> https://github.com/bitcoin/bips/blob/master/bip-0054.md
>
> Here's the proposed expansion:
>
> -------
> ## Miner forward compatibility
>
> [...]
>
> The coinbase transaction is usually crafted by mining pool software. To
> the best of the authors'
> knowledge, there does not exist an open source reference broadly in use
> today for such software.
> We encourage mining pools to update their software to craft coinbase
> transactions that are
> forward-compatible with the changes proposed in this BIP. This can be done
> by using the new
> `getblocktemplate` fields described below, once node software supports it.
>
> ## getblocktemplate changes
>
> The template Object of the `getblocktemplate` JSON-RPC call
> ([bip-0022][BIP22]) is extended with
> the following keys:
>
> | Key | Required | Type | Description |
> |-----|----------|------|-------------|
> | `coinbase_locktime` | Yes | Number | coinbase `nLockTime` value |
> | `coinbase_sequence` | Yes | Number | coinbase `nSequence` value |
> | `coinbase_version` | Yes | Number | coinbase `nVersion` value |
>
> Types are JSON types as defined in [bip-0022][BIP22].
>
> The `coinbase_locktime` field specifies the exact value that MUST be used
> for the coinbase
> transaction's `nLockTime` field.
>
> The `coinbase_sequence` field specifies a value that SHOULD be used for
> the coinbase transaction
> input's `nSequence` field. If a different value is used, it MUST NOT be
> `0xffffffff`[^12].
>
> The `coinbase_version` field specifies the value that SHOULD be used for
> the coinbase transaction's
> `nVersion` field[^13].
>
> -------
>
> Footnotes:
>
> [^12]: **Why SHOULD for `coinbase_sequence`?**
> The only consensus constraint on `nSequence` is to disallow `0xffffffff`.
> The server could communicate this via a bit mask, but for simplicity it
> provides the entire `nSequence` value. Clients SHOULD use this value, so
> that future soft forks can safely add additional constraints.
> [^13]: **Why is `coinbase_version` included?**
> This BIP does not constrain the coinbase transaction's `nVersion`, but
> including it means `getblocktemplate` now covers all coinbase transaction
> fields that could potentially be constrained by a future soft fork. The
> coinbase input's prevout txid (32 zero bytes) and vout index
> (`0xffffffff`)
> are fixed by consensus, so they can be safely hardcoded in mining
> software.
> At the time of writing, there is no consensus constraint on transaction
> versions. Transaction version 2 is the latest version with defined
> semantics, as specified in [bip-0068][BIP68], but its relative lock-time
> rules do not apply to the coinbase input. Nonetheless, clients SHOULD use
> this value so that they don't need to be updated if a future soft fork
> constrains `nVersion`.
>
> ---
>
> - Sjors Provoost
>
>
>
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>
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next prev parent reply other threads:[~2026-02-10 9:11 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-09 19:37 Sjors Provoost
2026-02-10 5:12 ` Melvin Carvalho [this message]
2026-02-10 7:53 ` Sjors Provoost
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