CXL Linux Sync: Ground Rules

  • Do not share confidential information
  • Do not share confidential product details
  • Do not disclose CXL consortium confidential information
  • Do discuss any Linux questions about released CXL specifications:
  • Do use IRC as a supplement for this sync meeting
    • #cxl on irc.oftc.net

November 2022

Agenda 11/29

  • Opens:
    • FSDAX ->notify_failure() regression work still pending
    • Others?
  • Fixes merged for v6.1-rc4
  • v6.2 merge window status
  • Post v6.2 Features

v6.1-rc4 Fixes

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tag/?h=v6.1-rc4

Merged:

  • Mailbox input payload fix
  • Decoder commit crash
  • LSA payload handling fix
  • CFMWS NUMA Node setup
  • Fix switch attached to single-port host-bridge
  • BUG in create-region when no more intermediate port decoders available
  • Fix region object memory leak
  • Fix memdev object memory leak
  • cxl_pmem static analysis fix

v6.2 Merge Window Status

Merged:

  • Cache invalidation for region physical invalidation scenarios
  • DOE kernel/user access collision detection
  • RCH preparation patches

In the queue (has review):

  • RCH Support (including DVSEC Range Register enumeration)
  • Security commands (including background commands)
  • CXL Events to Linux Trace Events (including interrupts)
  • RAS Capability Tracing on RCH and VH AER events

In the queue (needs review):

  • XOR Interleave Math support
  • Forward and reverse address translation (DPA <==> HPA)
  • Poison retrieval
  • cxl_pmem_wq removal
  • EFI CPER record parsing for CXL error records

At risk:

  • Volatile Region Discovery
  • Volatile Region Provisioning
    • CDAT + QTG _DSM integration
  • Poison inject and clear
  • CXL perf monitoring

Post v6.2 Features

  • MLD Mailbox support for DCD event injection
  • Dynamic Capacity Device support
    • Sparse DAX Region infrastructure
    • DCD event plumbing
  • Switch mailbox CCI
    • Multi-head device mailbox tunneling
  • Standalone CXL IDE
    • PCIE SPDM pre-requisite
  • Maintenance Feature Support (DRAM PPR)
  • Default “Soft Reserved” (EFI_MEMORY_SP) handling policy (cxl-cli + daxctl)

October 2022

Agenda 10/25

  • Opens:
    • FSDAX page reference counting rework (merged in mm-unstable)
    • FSDAX ->notify_failure() regression work still pending
    • Code First ECR: ‘SP’ attribute in SRAT
    • QEMU emulation status update
    • Others?
  • Fixes pending for v6.1-rc
  • Features in flight for v6.2
  • Rough plans for post v6.2 work

v6.1 Fixes

https://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl.git/log/?h=fixes

Queued:

  • Mailbox input payload fix
  • Decoder commit crash
  • LSA payload handling fix
  • CFMWS NUMA Node setup

Pending:

  • Fix switch attached to single-port host-bridge
  • BUG in create-region when no more intermediate port decoders available

v6.2 Features

In rough priority order, feedback welcome:

  • RCH Support (including DVSEC Range Register enumeration)
  • Cache invalidation for region physical invalidation scenarios
  • RAS Capability Tracing on RCH and VH AER events
  • CXL Events to Linux Trace Events (including interrupts)
  • EFI CPER record parsing for CXL error records
  • Forward and reverse address translation (DPA <==> HPA)
  • Volatile Region Discovery
  • Volatile Region Provisioning
  • Security commands (including background commands)
  • CXL perf monitoring
  • Miscellaneous cleanups and renames

Post v6.2 Features

  • Dynamic Capacity Device support
    • Sparse DAX Region infrastructure
    • DCD event plumbing
  • Maintenance Feature Support (DRAM PPR)
  • Switch mailbox CCI
    • Multi-head device mailbox tunneling
  • Default “Soft Reserved” (EFI_MEMORY_SP) handling policy (cxl-cli + daxctl)

August 2022

Agenda 8/30

  • Opens:
    • FSDAX ->notify_failure() fixes
    • FSDAX page reference counting rework
  • Linux v6.0-rc1 and ndctl (ndctl, daxctl, cxl-cli) v74 released
  • Fix and Feature queue for v6.0-rc, v6.1 and ndctl-v75
  • Rough plans for post v6.1 work for CXL 3.0 enabling

Recently released

  • Kernel:
    • DPA Space Accounting
    • PMEM Region Provisioning
    • DOE Support in PCI core
    • CDAT retrieval (for debug)
  • User tooling:
    • cxl create-region
    • cxl reserve/free-dpa
    • cxl list -vvv

Next fixes and features

  • ‘arch_flush_memregion()’
  • Fix validation of x1 switch topologies
  • Volatile region provisioning
  • Region labels
  • Security commands support
  • Trace events for CXL events (including interrupts)
  • ‘cxl monitor’ command
  • CXL AER handling
  • Address translation

Future work

  • Performance monitoring
  • Maintenance Feature Support (DRAM PPR)
  • Dynamic Capacity Device support
  • Default “Soft Reserved” (EFI_MEMORY_SP) handling policy

July 2022

Agenda 7/26

  • Opens:
    • FSDAX page reference counting rework
  • What is queued for v6.0 (and ndctl-v74)?
  • Late v6.0 updates
  • Post v6.0 work

Queued for v6.0

  • DOE Support in PCI core
  • CDAT retrieval (for debug)
  • DPA Space Accounting
  • PMEM Region Provisioning

In review for v6.0

Post v6.0 material

  • Pre-existing region enumeration
  • Volatile region provisioning
  • XORMAP interleave support
  • Trace Events for CXL Events
  • List Poison
  • Scan Media
  • Address translation
  • Region persistence in labels
  • Region enumeration via labels

June 2022

Agenda: 6/28

  • Opens:
    • CXL Device Tree Support
    • MEM_HWINIT_MODE=0
    • QEMU mainline CXL support is live
  • What is in review for v5.20 (and ndctl-v74)
  • What else might make v5.20?
  • What is post v5.20 material?

v5.20 in review

v5.20 on deck

  • Pre-existing region enumeration
  • Region persistence in labels
  • Region enumeration via labels
  • Address translation foundation

Post v5.20 material

  • List Poison
  • Scan Media
  • XORMAP interleave support
  • Trace Events for CXL Events
  • Address translation (in cxl-cli) for all kernel supported Events, List Poison, and Scan Media

May 2022

Agenda: 5/31

  • What is in v5.19?
  • What is on deck for v5.20?
  • What is post v5.20 material?
  • Opens

v5.19 / ndctl-v73

  • Kernel
    • lockdep annotations
    • CXL _OSC (native CXL hotplug + error “handling”)
    • Disable suspend
    • Mem_enable fixes

v5.20 / ndctl-v74

  • Kernel
    • Region Provisioning
    • DOE Core
    • CXL CDAT Retrieval
    • Event record handling core
      • Scan Media records
      • Event Interrupts
      • Background command timesharing
  • Userpace
    • ‘cxl create-region’
    • Region listing support
    • Scan media / Event records to json
    • Address translation

Post v5.20 / v6.0

  • Kernel
    • SPDM Attestation
    • IDE
    • Security commands
  • Userspace
    • Attestation helper process
    • CXL Device-DAX Policy