Welcome to the ampere-lts-kernel wiki!

There are cases to run upstream longterm maintenance kernel on the Ampere Altra® reference platform. This guide lists Linux kernel patches and kernel configurations related with Ampere Altra®, targeting for longterm 5.4 kernel. The guide is based on the Ampere Altra® Linux Kernel Porting Guide.

Kernel patches and configurations are back ported from Ampere centos kernel. Kernel patch is on linux-5.4.y branch: https://github.com/AmpereComputing/ampere-lts-kernel/tree/linux-5.4.y

kdump: reserve crashkernel above 4GB

• Patch details: https://github.com/AmpereComputing/ampere-lts-kernel/issues/102
• Background: https://github.com/AmpereComputing/ampere-lts-kernel/wiki/kdump-on-arm64

eventpoll bug fix

Issue: https://github.com/AmpereComputing/ampere-lts-kernel/issues/72

Accepted Kernel	Hash Tag	Subject
5.12	e9e15f48	locking/qrwlock: Fix ordering in queued_write_lock_slowpath()

NUMA

Issue: https://github.com/AmpereComputing/ampere-lts-kernel/issues/73

These patches provide multi-socket optimization:

Accepted Kernel	Hash Tag	Subject
5.10	409b032	arm64: NUMA: Kconfig: Increase NODES_SHIFT to 4
N/A	30abc1a	NOUPSTREAM: arm64: Kconfig: Enable NODES_SPAN_OTHER_NODES config for NUMA

ARM64

Issue: https://github.com/AmpereComputing/ampere-lts-kernel/issues/78

This patch is required to fix PCI ECAM reading:

Accepted Kernel	Hash Tag	Subject
5.10	44b1b99	drivers/pci: Add ecam quirk for Ampere Altra SOC.

Issue: https://github.com/AmpereComputing/ampere-lts-kernel/issues/79

This patch is required to fix soft lockup during heavy stress test:

Accepted Kernel	Hash Tag	Subject
5.8	480804b	BACKPORT: Split the old READ_IMPLIES_EXEC workaround from executable.

HW Monitor

Issue: https://github.com/AmpereComputing/ampere-lts-kernel/issues/80

These patches are required to support HW monitor:

Accepted Kernel	Hash Tag	Subject
TBD - 5.11?	8109a6c	hwmon: Add Ampere Altra HW monitor driver

APEI

Issue: https://github.com/AmpereComputing/ampere-lts-kernel/issues/81

These patches are required to support APEI/RAS features:

Accepted Kernel	Hash Tag	Subject
5.8	af3b585	BACKPORT: mm/memory-failure: Add memory_failure_queue_kick()
5.8	16ac324	BACKPORT: ACPI / APEI: Kick the memory_failure() queue for synchronous err

PMU

CMN-600 Issue: https://github.com/AmpereComputing/ampere-lts-kernel/issues/74

ARM DSU Issue: https://github.com/AmpereComputing/ampere-lts-kernel/issues/75

DMC-620 Issue: https://github.com/AmpereComputing/ampere-lts-kernel/issues/76

Accepted Kernel	Hash Tag	Subject
		CMN-600
5.10	80264b8	perf:Add Arm CMN-600 DT binding
5.10	cdaf907	perf: Add Arm CMN-600 PMU driver
5.12	2aef8e0	BACKPORT: perf/arm-cmn: Move IRQs when migrating context
Not upstream	ad71283	perf/arm-cmn: Fix kernel crash when access dtc object sharing same IRQ number
		ARM DSU
5.10	92163d	perf: arm_dsu: Support DSU ACPI devices
TBD	48b4d60	NOUPSTREAM:perf: arm_dsu: Allow IRQ to be shared among devices
		DMC-620
5.11	8895c29	perf: Add ARM DMC-620 PMU driver
5.11	51af7e2	perf: arm_dmc620: Update ACPI ID
		ARM SMMUv3 PMU (PMCG)
5.5	a4b00c9	perf/smmuv3: Remove the leftover put_cpu() in error path
5.8	779bed7	perf/smmuv3: Allow sharing MMIO registers with the SMMU drive
5.14	5cfcc6261	perf/smmuv3: Don't trample existing events with global filter

Altra LED driver

Issue: https://github.com/AmpereComputing/ampere-lts-kernel/issues/82

Not upstream yet.

Accepted Kernel	Hash Tag	Subject
TBD	5a19482	led: Add Altra LED driver

smmu-pmu PMCG

Fix smmu-pmu PMCG conflicts with nvme, see this issue: https://github.com/AmpereComputing/ampere-lts-kernel/issues/30

Issue: https://github.com/AmpereComputing/ampere-lts-kernel/issues/77

Accepted Kernel	Hash Tag	Subject
5.8	87957b27f	iommu/arm-smmu-v3: Don't reserve implementation defined register space

PMU NMI

Issue: https://github.com/AmpereComputing/ampere-lts-kernel/issues/83

This patch serials enable Non-maskable-interrupt for PMU. Please refer to wiki: https://github.com/AmpereComputing/ampere-lts-kernel/wiki/perf-pmu-and-more#pmu-non-maskable-interrupt-nmi for details.

The patch serial includes three parts:

1. pseudo-NMIs. The feature is in upstream 5.1 kernel, no need to backport.
2. PMU NMI based on pseudo-NMIs, totally 7 patches

Upstream kernel	Patch-set for pmu nmi
5.14	1aa0030 77bb12e c21bbca 1aa0030 cc3a384 de91dc3 ccc2351 9b87ed3

3. Fix PMU NMI hang issue

Upstream kernel	Patch-set for 'arm64: Fix cpuidle/suspend with pseudo-NMI enabled'
5.14	0036b25 497e665 662d30f a91183eb

Perf tool

Issue: https://github.com/AmpereComputing/ampere-lts-kernel/issues/84

Enhance linux perf tool features. These patches is not required for Altra.

Upstream kernel	Patch-set for 'perf kvm stat'
5.14	7129c5a 35b65b84 f7408370 35938d93

scsi: mpt3sas

Fix CPU lock up when doing fio test. The issue is because of the driver didn't handle IRQ correctly when number of cores greater than number of MSIx supported

Accepted Kernel	5.4 kernel version	Hash Tag	Subject
5.9	5.4.66	122cdbd	scsi: mpt3sas: Don't call disable_irq from IRQ poll handler

APEI

Accepted Kernel	5.4 kernel version	Hash Tag	Subject
5.8	5.4.69	af02933	arm64: acpi: Make apei_claim_sea() synchronise with APEI's irq work

PMU

Accepted Kernel	5.4 kernel version	Hash Tag	Subject
5.8	Already in 5.4.93	b1d2d3d	ACPI/IORT: Fix PMCG node always look for a single ID mapping

Please refer to altra_5.4_defconfig. It is based on Ampere centos 8 default kernel configure.

Significant changes are:

Ampere centos 8 kernel	5.4.93 kernel
CONFIG_ARM64_USER_VA_BITS_52=y	replaced by CONFIG_ARM64_VA_BITS_52=y
CONFIG_SYSTEM_TRUSTED_KEYS="certs/rhel.pem"	not set

Enabled features:

Features	Configures
64KB page	CONFIG_ARM64_64K_PAGES=y
numa nodes	CONFIG_NODES_SHIFT=6
Altra HW monitor driver	CONFIG_SENSORS_ALTRA=m
Altra LED driver	CONFIG_LEDS_ALTRA_SPCI=y
Arm CMN-600 PMU	CONFIG_ARM_CMN=y
ARM DynamIQ Shared Unit (DSU) PMU	CONFIG_ARM_DSU_PMU=y
DMC-620 PMU	CONFIG_ARM_DMC620_PMU=y
ARMv8.2 Statistical Profiling Extension	CONFIG_ARM_SPE_PMU=y
ARM SMMUv3 Performance Monitors Extension	CONFIG_ARM_SMMU_V3_PMU=y

For each kernel patch, there is a functional test case. The test cases are tracked in https://github.com/AmpereComputing/ampere-lts-kernel/issues/6