Upstream patch carry

EPICS-env builds Experimental Physics and Industrial Control System (EPICS) base and each module from a pinned upstream tag or commit. When a pinned source needs a fix that the pin does not contain, EPICS-env carries the fix as a patch file under patch/ and applies it to the cloned source during the patch stage. The pin in configure/RELEASE stays unchanged; a carried patch and a version bump are separate changes. Carry an upstream fix as a patch adds a patch, Verify a fix against an installed tree tests one, and Upstream patch targets lists the targets.

Patch file families and names

The file name decides which target applies a patch and to which source tree:

The placeholders in the names mean:

• <base_version> and <pvxs_version> are the values of SRC_VER_BASE and SRC_VER_PVXS, such as 7.0.10 and 1.5.2.
• <NNNN> is the number of the upstream pull request (PR) that merged the fix, written with four digits.
• <NN> is a two-digit sequence number, and <sha7> is the first seven characters of the upstream commit.
• <slug> is a short description of the fix.

For the pins in configure/RELEASE, patch/ holds 18 EPICS base carry patches for 7.0.10 and 12 pvxs carry patches for 1.5.2. No 7.0.10.base.p0.patch exists, so patch.base.apply does nothing.

Version-anchored names that drop on a bump

The carry targets select their files with a pattern that starts with the pinned version:

When the pin of EPICS base or pvxs moves to another version, its pattern matches no file, and the whole carry set for that source stops applying. Every carried fix then needs a review against the release that the pin names, and a carry patch never reaches a version it was not written for.

The hyphen after the version keeps the carry pattern apart from the site patch <base_version>.base.p0.patch. The pvxs pattern 1.5.2-* also never matches the file pvxs-1.3.1.p0.patch.

Sorted apply and exact reverse revert

A carry target applies its files in the sorted order of their names, and the matching revert target removes them in the exact reverse order. Patches that touch the same file then apply and revert against the source state each one expects.

Revert targets classify each whole patch with noninteractive dry-runs. They skip confirmed unapplied patches and reverse confirmed applied patches. Conflicts, partial application, required-input absence, and unresolved states stop the invocation; earlier completed reversals remain in effect.

Later carry patches can depend on context from earlier patches. Classification can prepare that context in a private copy of real source files, preserving the original tree. For supported single-hunk static C function patches, it also checks the named function to distinguish similar code in other functions. Private hunk search positions follow that function when independent source edits move it. Patch contents must match inside the function; an absent or duplicate function leaves the state unresolved.

Sorting compares names as text. Within the EPICS base set, the two-digit commit form sorts before the pull request form, because a digit sorts before p. The EPICS base set for 7.0.10 therefore applies 7.0.10-01-b2d2758-putnotify-type-check.p0.patch first, followed by the pull request patches in ascending number.

Each file goes through patch -d <source_tree> --ignore-whitespace -p0. The carry targets stop at the first file that fails, so a later success cannot hide an earlier failure. The pvxs targets also pass --no-backup-if-mismatch, so a patch that applies at an offset leaves no .orig backup file in the source tree. All revert targets suppress mismatch backups and preserve existing backups.

The patch aggregate applies every family in a fixed order, and patch.revert lists the same targets in the exact reverse order:

1. patch.base.apply
2. patch.base.pr.apply
3. patch.mca.apply
4. patch.measComp.apply
5. patch.measComp.tc32.apply
6. patch.opcua.apply
7. patch.opcua.export.apply
8. patch.feed-core.apply
9. patch.QPC.apply
10. patch.pvxs.commit.apply
11. patch.StreamDevice.apply

Fixed per-module patches

A fixed patch has no version in its name, and one dedicated target pair applies and reverts it. It keeps applying after the module pin changes, until it fails to apply to the changed source and make patch stops.

The Target column names the prefix of the .apply, .revert, and .make targets.

The feed-core and QPC patches remove module references from Makefile files that the module dependency audit check.module-deps reads. On the current pins, the strict audit passes in all four combinations: both patches applied, only feed-core applied, only QPC applied, and neither applied. These patches define the selected build content; passing the audit does not require them. Build and install verification gates describes that audit.

Patch file format

Every patch file is a unified diff with no path prefix, the form that git diff --no-prefix writes. Paths in the file start at the top of the source tree, such as modules/database/src/std/rec/mbbiRecord.c for EPICS base, and the -p0 option applies them from there. The .p0.patch suffix marks this format.

The .make targets write a patch from the current changes in a source tree:

• patch.<name>.make writes the fixed patch of one module from the current changes in its source tree, limited for most modules to the files that patch covers.
• patch.base.make writes every change in epics-base-src to <base_version>.base.p0.patch.

No make target writes the EPICS base or pvxs carry files.

Inactive patch files

Some files under patch/ match no active target on a Linux build of the pinned versions: