LinuxKPI: Adding functions to mmu_notifier.h to satisify requirements to compile kfd_process.c in amdkfd driver
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Authored by siri_racha.ca on Jul 13 2026, 2:11 AM.

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I'm working on getting kfd_proces.c working, and it uses quite a few functions
from mmu_notifier in the LinuxKPI. I have added them in to allow the file to
compile. I will note that I did not fully implement them, and have left a
warning to expect issues if you execute the file.

DO NOT MERGE
I need to re-test this patch

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rG FreeBSD src repository

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siri_racha.ca created this revision.Jul 13 2026, 2:11 AM

Herald added subscribers: emaste, imp. · View Herald TranscriptJul 13 2026, 2:11 AM

siri_racha.ca requested review of this revision.Jul 13 2026, 2:11 AM

I have https://reviews.freebsd.org/D58169 open in case you want to see a pr_debug() example file with a lot more stubbed only functions.

sys/compat/linuxkpi/common/include/linux/mmu_notifier.h
30	#include <linux/kernel.h> /* for pr_debug */
37	While clear, the `#warning` is not needed. We have temporary placeholders in a lot of places in LinuxKPI. The important bit is that if return values are required, that they signal an error according to the API.
57	Where function arguments are no used, we could annotate them with __unused
59	Add before return: pr_debug("%s TODO\n", __func__); here and for all the functions below.
59	return (0); return values get ()

This revision now requires changes to proceed.Jul 13 2026, 8:14 AM

siri_racha.ca added inline comments.Jul 13 2026, 2:35 PM

sys/compat/linuxkpi/common/include/linux/mmu_notifier.h
37	Sounds good, I'll remove the warning and make the other changes But I am a bit concerned with just returning ENOSYS/ENOIMPL, because the driver might be bugged and not check the return value, and thus cause issues. Beyond pr_debug(...) is there something else I can/should add in?

bz added inline comments.Jul 13 2026, 2:52 PM

sys/compat/linuxkpi/common/include/linux/mmu_notifier.h
37	Well, all you return is 0 and NULL so far. I'll comment on those two below. If a driver is bugged beyond expectations then bugs need to be fixed but that is for that code and not this one here ;-) I know of nothing else to add beyond pr_debug().
59	-EINVAL is a valid return value for the function a driver needs to deal with, so you could use that.
70	ops != NULL && ... != NULL return ()
73	return (ERR_PTR(-EINVAL)); should be fine here.
79	Same here. != NULL checks for style.