Differential D54060

LinuxKPI: introduce LINUXKPI_DEBUG to enable LinuxKPI debugging
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Authored by bz on Dec 3 2025, 9:41 PM.

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linuxkpi

Summary

This allows us to build kernels which will (if the sysctl is enabled
too) to show pr_debug() and pr_devel() output.

Enable it by default for debug kernels.

This option can later also be used for other LinuxKPI parts, like
skbuffs, netdevice, rcu, ... to conditionally compile in debugging
support to further justify its existence beyond an in-code #define.

Sponsored by: The FreeBSD Foundation
MFC after: 3 days

Diff Detail

Repository

rG FreeBSD src repository

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Build Status

Buildable 69520
Build 66403: arc lint + arc unit

Event Timeline

bz created this revision.Dec 3 2025, 9:41 PM

Herald added subscribers: emaste, imp. · View Herald TranscriptDec 3 2025, 9:41 PM

bz requested review of this revision.Dec 3 2025, 9:41 PM

Harbormaster completed remote builds in B69025: Diff 167500.Dec 3 2025, 9:42 PM

bz planned changes to this revision.Dec 6 2025, 10:55 PM

bz added inline comments.

sys/conf/options
907	opt-Linuxkpi.h should likely also just be added to LINUXKPI_GENSRCS?

Also add opt_linuxkpi.h to LINUXKPI_GENSRCS by default.

Harbormaster completed remote builds in B69520: Diff 168754.Dec 30 2025, 12:26 AM

sys/conf/std.nodebug is missing

Add the missing std.nnodebug line.

If this is OK now and could go in then I could make more use of it.

Harbormaster completed remote builds in B73412: Diff 178531.May 24 2026, 11:24 PM

Unless there will be objections I'll put this in by Tuesday evening.

I just found another case this would be useful (turn some LinuxKPI lock debugging on -- instead of having SX_NOWITNESS). Would make ti so much easier to debug a deadlock.

And that is in addition to the pr_debug calls with th sysctl, skbuff DEBUG and other subsystem DBEUG #ifdefs which most could vanish with this....

emaste added a project: linuxkpi.Mon, Aug 17, 5:01 PM

I've just added another "first" use case (disable NOWITNESS), so it would be really nice to start getting this in.