doc: document capnproto and libmultiprocess deps in 29.x

willcl-ark commented at 1:09 pm on October 14, 2025: member

These dependencies are both undocumented, and libmultiprocess has a relatively special requirement in that v6.0 and later are know to not work with v29.x of Bitcoin Core.

DrahtBot added the label Backport on Oct 14, 2025

DrahtBot commented at 1:09 pm on October 14, 2025: contributor

The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

Code Coverage & Benchmarks

For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/33623.

Reviews

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Type	Reviewers
Concept ACK	sipa, fanquake
Stale ACK	ryanofsky

If your review is incorrectly listed, please copy-paste <!–meta-tag:bot-skip–> into the comment that the bot should ignore.

sipa commented at 1:20 pm on October 14, 2025: member

Concept ACK

fanquake added this to the milestone 29.3 on Oct 14, 2025

in doc/dependencies.md:40 in ad73a8e254

35@@ -36,3 +36,8 @@ Bitcoin Core requires one of the following compilers.
36 | [SQLite](../depends/packages/sqlite.mk) (wallet) | [link](https://sqlite.org) | [3.38.5](https://github.com/bitcoin/bitcoin/pull/25378) | [3.7.17](https://github.com/bitcoin/bitcoin/pull/19077) | No |
37 | Python (scripts, tests) | [link](https://www.python.org) | N/A | [3.10](https://github.com/bitcoin/bitcoin/pull/30527) | No |
38 | [systemtap](../depends/packages/systemtap.mk) ([tracing](tracing.md)) | [link](https://sourceware.org/systemtap/) | [4.8](https://github.com/bitcoin/bitcoin/pull/26945)| N/A | No |
39+| [capnproto](../depends/packages/capnp.mk) ([multiprocess](multiprocess.md)) | [link](https://capnproto.org/) | [1.2.0](https://github.com/bitcoin/bitcoin/pull/32760)| N/A | No |
40+| [libmultiprocess*](../depends/packages/libmultiprocess.mk) ([multiprocess](multiprocess.md)) | [link](https://github.com/bitcoin-core/libmultiprocess) | [1954f7f65661d49e700c344eae0fc8092decf975](https://github.com/bitcoin-core/libmultiprocess/tree/1954f7f65661d49e700c344eae0fc8092decf975)| N/A | No |

ryanofsky commented at 8:29 pm on October 15, 2025:

I went ahead and created a v5.0 tag pointing at this revision, as well as tags for versions used by other bitcoin core releases, described in https://github.com/bitcoin-core/libmultiprocess/pull/228.

So it might make sense to replace 1954f7f65661d49e700c344eae0fc8092decf975 with 5.0 here, or maybe just add (5.0) after if we think it is important to specify the exact hash.

It’d also be possible to update the depends file:

 0diff --git a/depends/packages/native_libmultiprocess.mk b/depends/packages/native_libmultiprocess.mk
 1index 4467dee76f50..a76304f9f050 100644
 2--- a/depends/packages/native_libmultiprocess.mk
 3+++ b/depends/packages/native_libmultiprocess.mk
 4@@ -1,8 +1,8 @@
 5 package=native_libmultiprocess
 6-$(package)_version=1954f7f65661d49e700c344eae0fc8092decf975
 7+$(package)_version=v5.0
 8 $(package)_download_path=https://github.com/bitcoin-core/libmultiprocess/archive
 9 $(package)_file_name=$($(package)_version).tar.gz
10-$(package)_sha256_hash=fc014bd74727c1d5d30b396813685012c965d079244dd07b53bc1c75c610a2cb
11+$(package)_sha256_hash=401984715b271a3446e1910f21adf048ba390d31cc93cc3073742e70d56fa3ea
12 $(package)_dependencies=native_capnp
13 
14 define $(package)_config_cmds

The sha256 hash nees to be updated there just because the tarball github generates has a different top-level directory name. Tested with:

make -C depends MULTIPROCESS=1 native_libmultiprocess_fetched make -C depends MULTIPROCESS=1 native_libmultiprocess_built

willcl-ark commented at 10:10 pm on October 15, 2025:

Nice, thanks!

I double-checked the tag points to the correct commit and tested a depends build using your package suggestion which all worked fine.

Have therefore gone ahead with updating the depends package and dependencies.md in bf236d7a8af0826efc39a04113b79f96fe05f0c7 as you suggest.

ryanofsky approved

ryanofsky commented at 8:31 pm on October 15, 2025: contributor

Code review ACK ad73a8e2540005f0d81310e10b61c4a61897b217. Thanks for the documentation! This change looks good as-is but i think it could also make sense to reference a version number instead of a commit hash so I left a suggestion below.

DrahtBot requested review from sipa on Oct 15, 2025

willcl-ark force-pushed on Oct 15, 2025

maflcko added the label DrahtBot Guix build requested on Oct 16, 2025

in doc/dependencies.md:40 in bf236d7a8a

35@@ -36,3 +36,8 @@ Bitcoin Core requires one of the following compilers.
36 | [SQLite](../depends/packages/sqlite.mk) (wallet) | [link](https://sqlite.org) | [3.38.5](https://github.com/bitcoin/bitcoin/pull/25378) | [3.7.17](https://github.com/bitcoin/bitcoin/pull/19077) | No |
37 | Python (scripts, tests) | [link](https://www.python.org) | N/A | [3.10](https://github.com/bitcoin/bitcoin/pull/30527) | No |
38 | [systemtap](../depends/packages/systemtap.mk) ([tracing](tracing.md)) | [link](https://sourceware.org/systemtap/) | [4.8](https://github.com/bitcoin/bitcoin/pull/26945)| N/A | No |
39+| [capnproto](../depends/packages/capnp.mk) ([multiprocess](multiprocess.md)) | [link](https://capnproto.org/) | [1.2.0](https://github.com/bitcoin/bitcoin/pull/32760)| N/A | No |
40+| [libmultiprocess*](../depends/packages/libmultiprocess.mk) ([multiprocess](multiprocess.md)) | [link](https://github.com/bitcoin-core/libmultiprocess) | [5.0](https://github.com/bitcoin-core/libmultiprocess/releases/tag/v5.0)| N/A | No |

ryanofsky commented at 7:32 am on October 16, 2025:

In commit “doc: document capnproto and libmultiprocess deps” (bf236d7a8af0826efc39a04113b79f96fe05f0c7)

I think this could list 0.7.0 as minimum required version of Cap’n Proto linking to https://github.com/bitcoin-core/libmultiprocess/pull/88 (which dropped support for previous Cap’n Proto versions) and list 5.0 as minimum required version of libmultiprocess linking to #31740 (which added a dependency on the mp/type-*.h files that were introduced in v5)

willcl-ark commented at 4:43 pm on November 25, 2025:

Thanks, suggestions taken in 1d2251850dd

in doc/dependencies.md:43 in bf236d7a8a

35@@ -36,3 +36,8 @@ Bitcoin Core requires one of the following compilers.
36 | [SQLite](../depends/packages/sqlite.mk) (wallet) | [link](https://sqlite.org) | [3.38.5](https://github.com/bitcoin/bitcoin/pull/25378) | [3.7.17](https://github.com/bitcoin/bitcoin/pull/19077) | No |
37 | Python (scripts, tests) | [link](https://www.python.org) | N/A | [3.10](https://github.com/bitcoin/bitcoin/pull/30527) | No |
38 | [systemtap](../depends/packages/systemtap.mk) ([tracing](tracing.md)) | [link](https://sourceware.org/systemtap/) | [4.8](https://github.com/bitcoin/bitcoin/pull/26945)| N/A | No |
39+| [capnproto](../depends/packages/capnp.mk) ([multiprocess](multiprocess.md)) | [link](https://capnproto.org/) | [1.2.0](https://github.com/bitcoin/bitcoin/pull/32760)| N/A | No |
40+| [libmultiprocess*](../depends/packages/libmultiprocess.mk) ([multiprocess](multiprocess.md)) | [link](https://github.com/bitcoin-core/libmultiprocess) | [5.0](https://github.com/bitcoin-core/libmultiprocess/releases/tag/v5.0)| N/A | No |
41+
42+\* Note that libmultiprocess v5.0 is the **latest** version that will work with Bitcoin Core v29.x due to numerous updates since [PR#164](https://github.com/bitcoin-core/libmultiprocess/pull/164) which will not be backported to this branch.
43+Users providing libmultiprocess themselves (i.e. not via depends) should not build any later version or commit than this.

ryanofsky commented at 7:41 am on October 16, 2025:

In commit “doc: document capnproto and libmultiprocess deps” (bf236d7a8af0826efc39a04113b79f96fe05f0c7)

I think I’d suggest dropping this paragraph because we can’t really say 5.0 is the latest version that will work. There is a v5 branch, so in theory if there were fixes or features we wanted to backport it would be possible to create 5.1, 5.2, etc versions that should be compatible with 5.0.

Libmultiprocess doesn’t seem different than other dependencies like python and sqlite in this respect: we don’t know what future versions may be compatible with current code and don’t try to make promises or predictions about them here.

I guess this could say something like “* Libmultiprocess 6.0 and later versions are no longer compatible due to https://github.com/bitcoin-core/libmultiprocess/pull/160" if that would be helpful, though. And maybe move the asterisk to the “Minimum required” column since this information would seem more relevant there.

willcl-ark commented at 4:44 pm on November 25, 2025:

Suggestions here also taken in 1d2251850dd.

I opted to keep the suggested sentence, as I feel like stating (somewhere) that v6.0+ is known to not work is useful.

ryanofsky approved

ryanofsky commented at 8:11 am on October 16, 2025: contributor

Code review ACK bf236d7a8af0826efc39a04113b79f96fe05f0c7. Looks good but left some more suggestions below. I think I might also adjust PR description not to say documented version is the latest version that will ever work (see below). I think it would be more accurate just to say that later versions are known not to work.

DrahtBot commented at 10:00 pm on October 16, 2025: contributor

Guix builds (on x86_64) [untrusted test-only build, possibly unsafe, not for production use]

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DrahtBot removed the label DrahtBot Guix build requested on Oct 16, 2025

fanquake commented at 3:45 pm on November 25, 2025: member

Concept ACK - @willcl-ark did you want to address any of the suggestions here?

doc: document capnproto and libmultiprocess deps

These dependencies are both undocumented, and libmultiprocess has a
relatively special requirement in that v6.0 and later are know to not
work with v29.x of Bitcoin Core.

1d2251850d

willcl-ark force-pushed on Nov 25, 2025

willcl-ark commented at 4:44 pm on November 25, 2025: member

Concept ACK - @willcl-ark did you want to address any of the suggestions here?

Sorry, PR updated now, taking @ryanofsky’s suggestions.

doc: document capnproto and libmultiprocess deps in 29.x #33623

Code Coverage & Benchmarks

Reviews

Guix builds (on x86_64) [untrusted test-only build, possibly unsafe, not for production use]