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Differential D54297

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

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

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rG FreeBSD src repository
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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
bz added a comment.Dec 18 2025, 10:39 PM

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

bz planned changes to this revision.Dec 18 2025, 10:41 PM

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

bz requested review of this revision.Dec 18 2025, 10:52 PM
bz added a child revision: D54301: sys/bitcount.h: add __const_bitcount<n>.

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

bz added a reviewer: emaste.Dec 18 2025, 10:56 PM

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

bz added a comment.Dec 18 2025, 10:59 PM

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.Jan 16 2026, 8:50 AM

Revision Contents
Changeset List

PathSize
sys/
compat/
linuxkpi/
common/
include/
linux/
8 lines
modules/
3 lines

Diff 168462

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

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sys/modules/Makefile

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