Fulcrum 2.1.2:1 - BLAKE2b Support

Superseded by v2.1.2_2. Installing this version over a stock Fulcrum leaves the service crash-looping on a magic bytes mismatch, with no way to clear it from the interface. The newer release detects that and rebuilds the index automatically.

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Fulcrum with BLAKE2b hard fork support, packaged for StartOS, rebuilt on upstream Fulcrum 2.1.2.

Supersedes v2.1.1_19, which was built on Fulcrum 2.1.0 and carries a version that the marketplace release of Fulcrum outranks. Installing that one leads to it being replaced by the stock build, which then refuses to open the index and stops.

What this is

The BLAKE2b hard fork changes the proof of work at an activation height: from that block on, block headers are 164 bytes and hashed with BLAKE2b rather than 80 bytes and SHA256d. History is continuous, so blocks below that height keep their original headers and both forms coexist in one index. Stock Fulcrum cannot parse the new form and stops at the activation block rather than serving wrong data. This build reads both.

Activation status

The fork is live on both networks. Bitcoin Knots v29.4.1.knots20260508rc4 schedules it at height 961640 on mainnet and 150308 on testnet4, and both have crossed it. Nothing here carries an activation height: header size is read from the version word of each header, so this package follows whatever schedule the node it indexes is built with.

The testnet4 schedule has moved three times, 149460 to 149537 to 150027 to 150308, and the chain that activated at each earlier height was abandoned when the next release replaced it. Expect a node that follows a moved schedule to reorganise away from the chain it was on, and this index to follow it there.

Index compatibility

Header records are 164 bytes here rather than 80, and the headers table magic differs, so an index written by the marketplace build is not readable by this one and vice versa. Either direction fails with an explicit magic bytes mismatch rather than misreading data, and moving between them costs a full resync.

Note that the marketplace build will replace this package whenever its version sorts higher. Fulcrum then refuses to start until this package is installed again. Reinstalling this s9pk restores it without a resync, provided the index was written by this build.

Verifying this download

gpg --import privkeyio-signing-key.asc
gpg --verify fulcrum_x86_64.s9pk.sha256.asc fulcrum_x86_64.s9pk.sha256
sha256sum -c fulcrum_x86_64.s9pk.sha256

Signed by Kyle Santiago kyle@privkey.io, key A47D99B6DB0D715D40C59A2023AE8A8EA7E24E38.

Built from blake2b-pow at f9e2c42, with Fulcrum from privkeyio/Fulcrum at tag v2.1.2-blake2b (30138c7).