LinuxKPI: bitcount fix gcc and older llvm builds
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Authored by bz on Dec 18 2025, 10:28 PM.

Details

Reviewers

dumbbell
imp
brooks
emaste

Group Reviewers

linuxkpi

Commits

rG9755a8036354: LinuxKPI: bitcount fix builds with gcc and older llvm
rG34892a8e3005: LinuxKPI: bitcount fix builds with gcc and older llvm

Summary

LLVM before 19 and gcc before 14 do not support builtin_popcountg().
Use const_bitcount<n> from sys/bitcount.h as a replacement in these
cases. This should still allow drm-kmod to build with size to be known
at compile-time.

Sponsored by: The FreeBSD Foundation
Fixes: 7cbc4d875971, 5e0a4859f28a
MFC after: 3 days
X-MFC: remove sys/modules/Makefile checks

Diff Detail

Repository

rG FreeBSD src repository

Lint

Lint Not Applicable

Unit

Tests Not Applicable

Event Timeline

bz created this revision.Dec 18 2025, 10:28 PM

Herald added a subscriber: emaste. · View Herald TranscriptDec 18 2025, 10:28 PM

bz requested review of this revision.Dec 18 2025, 10:28 PM

Harbormaster completed remote builds in B69385: Diff 168371.Dec 18 2025, 10:28 PM

I found @dumbbell initial replacement suggestion here still: https://github.com/freebsd/freebsd-src/commit/c5b671a393950f98b83089a42a9f1d69f7b9ce9c

And that makes me find that __const_bitcount<n> is another local change; I'll update this in a minute

Added https://reviews.freebsd.org/D54301 as well.

Adding @emaste as I found @dumbbell 's version through the stack of local changes you carry.

And for reference; pushing this out was triggered by https://reviews.freebsd.org/D54266

brooks accepted this revision.Dec 19 2025, 9:55 AM

This revision is now accepted and ready to land.Dec 19 2025, 9:55 AM

brooks mentioned this in D54266: iwlwifi: Don't compile for clang before 19.Dec 19 2025, 9:56 AM

emaste accepted this revision as: emaste.Dec 19 2025, 8:03 PM

Closed by commit rG34892a8e3005: LinuxKPI: bitcount fix builds with gcc and older llvm (authored by bz). · Explain WhyDec 19 2025, 9:24 PM

This revision was automatically updated to reflect the committed changes.

bz added a commit: rG34892a8e3005: LinuxKPI: bitcount fix builds with gcc and older llvm.

bz added a commit: rG9755a8036354: LinuxKPI: bitcount fix builds with gcc and older llvm.Fri, Jan 16, 8:50 AM

Revision Contents
Changeset List

Path

Size

sys/

compat/

linuxkpi/

common/

include/

linux/

bitops.h

8 lines

modules/

Makefile

3 lines

Diff 168462

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sys/compat/linuxkpi/common/include/linux/bitops.h