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Differential D58251

linuxkpi: Add `int_sqrt()`
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Authored by dumbbell on Jul 15 2026, 8:17 AM.
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linuxkpi
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rGd4820dc1e6cb: linuxkpi: Add `int_sqrt()`
Summary

The implementation comes from isqrt64() in sys/cam/cam_iosched.c. It is modified to take an unsigned long and return an unsigned int.

The i915 DRM driver started to use it in Linux 6.15.

Sponsored by: The FreeBSD Foundation

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rG FreeBSD src repository
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Event Timeline

dumbbell created this revision.Jul 15 2026, 8:17 AM
Herald added subscribers: emaste, imp. · View Herald TranscriptJul 15 2026, 8:17 AM
dumbbell requested review of this revision.Jul 15 2026, 8:17 AM
dumbbell added a parent revision: D58250: linuxkpi: Define `PCI_CLASS_BRIDGE_HOST`.
dumbbell added a child revision: D58252: linuxkpi: Fix return type of `kobject_uevent_env()`.
emaste added a project: linuxkpi.Aug 17 2026, 4:58 PM
bz requested changes to this revision.Sat, Sep 5, 9:28 AM
bz added a subscriber: bz.
bz added inline comments.
sys/compat/linuxkpi/common/include/linux/math.h
67

I believe int_sqrt returns an unsigned long in Linux.

sys/compat/linuxkpi/common/src/linux_math.c
10

Based on? instead of copied as it's not a 1:1 copy thought it may become if we do return the unsigned long? Otherwise also credit @imp in the (c)?

Also do you want to fix style for LinuxKPI?

This revision now requires changes to proceed.Sat, Sep 5, 9:28 AM
dumbbell updated this revision to Diff 186166.Mon, Sep 7, 7:24 PM

Based on the feedback from @bz:

  • Fix return type, it should have been unsigned long.
  • Improve comment to explain the source of the code.
dumbbell marked 2 inline comments as done.Mon, Sep 7, 7:25 PM
bz added inline comments.Mon, Sep 7, 10:44 PM
sys/compat/linuxkpi/common/src/linux_math.c
15

This is not common style for FreeBSD. Usually we take the license/copyright from the file and then keep it at the top.
However, if we expect more functions in this file one day then I actually like this idea (which will give a lot of tools sieving for copyright and licenses a headache) to mark just that part of the code.
However I have no clue if that actually makes a difference.

@imp this is your code and you know all the other bits related to this.

dumbbell updated this revision to Diff 186404.Thu, Sep 10, 6:24 PM
dumbbell marked an inline comment as done.

Address concern from @bz

sys/compat/linuxkpi/common/src/linux_math.c
15

I moved the copyright at the top like in all other places.

bz added inline comments.Thu, Sep 10, 7:06 PM
sys/compat/linuxkpi/common/src/linux_math.c
5

And now I have to ask for forgiveness.
The file of the commit ( ba6c22ce938ed ) says "Copyright (c) 2015 Netflix, Inc."

dumbbell updated this revision to Diff 186410.Thu, Sep 10, 7:30 PM

Address feedback from @bz.

I also messed up my git-blame(1) invocation…

dumbbell marked an inline comment as done.Thu, Sep 10, 7:30 PM
bz accepted this revision.Thu, Sep 10, 7:31 PM
This revision is now accepted and ready to land.Thu, Sep 10, 7:31 PM
Closed by commit rGd4820dc1e6cb: linuxkpi: Add `int_sqrt()` (authored by dumbbell). · Explain WhyThu, Sep 10, 7:50 PM
This revision was automatically updated to reflect the committed changes.
dumbbell added a commit: rGd4820dc1e6cb: linuxkpi: Add `int_sqrt()`.

Revision Contents
Changeset List

PathSize
sys/
compat/
linuxkpi/
common/
include/
linux/
3 lines
src/
43 lines
conf/
2 lines
modules/
linuxkpi/
1 line

Diff 186411

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

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sys/compat/linuxkpi/common/src/linux_math.c

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sys/conf/files

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sys/modules/linuxkpi/Makefile

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