x86: Add sysctl knobs for loader tunables
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Authored by zlei on Oct 16 2023, 7:05 AM.

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Summary

The following loader tunable do not have corresponding sysctl MIB
entries. Add them so that they can be retrieved, and sysctl -T will
also report them correctly.

hw.attach_intel_csr_pci
hw.cpu_stdext_disable
hw.dmar.enable
hw.dmar.fault_log_size
hw.dmar.ir
hw.dmar.pmr.disable
hw.dmar.qi
hw.dmar.qi_size
hw.x2apic_enable

MFC after: 1 week

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rG FreeBSD src repository

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zlei created this revision.Oct 16 2023, 7:05 AM

Herald added a subscriber: imp. · View Herald TranscriptOct 16 2023, 7:05 AM

zlei requested review of this revision.Oct 16 2023, 7:05 AM

zlei added inline comments.Oct 16 2023, 7:08 AM

sys/x86/iommu/intel_drv.c
163	I guess those knobs `hw.dmar.xxx` should be under `hw.iommu.dmar`.

zlei added inline comments.Oct 16 2023, 9:22 AM

sys/x86/iommu/intel_drv.c
163	I guess those knobs `hw.dmar.xxx` should be under `hw.iommu.dmar`. Found a history change https://reviews.freebsd.org/D25807 . So how should we process the inconsistency ? Maybe with a compile condition COMPAT_FREEBSD10 ? +#ifdef COMPAT_FREEBSD10 TUNABLE_UINT64_FETCH("hw.dmar.timeout", &timeout); +#endif + TUNABLE_UINT64_FETCH("hw.iommu.dmar.timeout", &timeout);

zlei added inline comments.Oct 17 2023, 2:45 AM

sys/x86/acpica/madt.c
200	Emm, we already have `hw.apic.x2apic_mode`, a `hw.x2apic_enable` seems redundant .

zlei added a parent revision: D42248: x86: Prefer consistent naming for loader tunables.Oct 17 2023, 9:48 AM

zlei added a child revision: D42249: amd64: Fix two typos of loader tunables.

Quote from D42233 by @kib

That said, I do not see much use for these and other x86-related tunables to be exposed as sysctl. They are debugging tools, useful only for people who understand the code.

kib added inline comments.Oct 18 2023, 4:49 PM

sys/x86/iommu/intel_drv.c
163	well, iommu == dmar. So if you want to rename, do it by hw.dmar => hw.iommu or hw.iommu.intel (because for AMD it would be different) COMPAT_FREEBSD10 does not make sense since it is present in 14 as well. But IMO this should not be kept, just rename the knobs. People that use them should know what they do, it is not a typical user tweak.
sys/x86/pci/qpi.c
65	Again not too useful. Either buses are attached and knob worked, or there are no buses visible.
sys/x86/x86/identcpu.c
1523	Not too useful to provide.