2021-3-22 Meeting Meeting notes

Meeting Details

Topic: linaro-open-discussion meeting
Time: March 22 , 2021 10.00 AM London

Join Zoom Meeting
https://linaro-org.zoom.us/j/4417312160

Meeting ID: 441 731 2160
One tap mobile
+16465588656,,4417312160# US (New York)
+16699009128,,4417312160# US (San Jose)

Dial by your location
+1 646 558 8656 US (New York)
+1 669 900 9128 US (San Jose)
+1 253 215 8782 US (Tacoma)
+1 301 715 8592 US (Washington D.C)
+1 312 626 6799 US (Chicago)
+1 346 248 7799 US (Houston)
877 853 5247 US Toll-free
888 788 0099 US Toll-free
Meeting ID: 441 731 2160
Find your local number: https://linaro-org.zoom.us/u/aUcYpPkSC

Attendees

• Lorenzo

• Vincent
• Jammy
• James Morse
• Souvik Chakravarty
• Jonathan
• Jean-Philippe
• Shameerali
• Salil
• Barry Song
• Yunsheng Lin
• Tao Zeng

Agenda

Confirmed topics

• CXL follow up discussion
  • https://lore.kernel.org/linux-acpi/CAPcyv4gmd_cygXK0PpGkXmJLC3_ctEpRvpi5P-QcuXusFX5oNQ@mail.gmail.com/
  • https://lore.kernel.org/linux-acpi/20201102183428.00005f4f@Huawei.com/
• Feedback on the virtual CPU hotplug implementation with PSCI
• AOB

Meeting Notes

• CXL on memory (Jonathan presented several new slides after the introduction in last call)
•  
  • Handling of memory on Type 2 devices (like GPU), two modes:
    • Host biased (coherency is managed as part of the host SoC)
    • Device biased (device issues coherence messages)
  • Vikram's question: how should it be presented by Firmware?
    • Problem 1: normal memory at boot can't be offlined later
      • Likely to need element of BIOS control
    • Problem 2: pinned memory in region
      • Patch sets under review to migrate memory out of ZONE_MOVABLE on pin
  • Generic Initiator Reminder
  • GI as bridge for CXL etc.
    • https://lore.kernel.org/linux-acpi/CAPcyv4gmd_cygXK0PpGkXmJLC3_ctEpRvpi5P-QcuXusFX5oNQ@mail.gmail.com/
• Virtual CPU hotplug
•  
  • Salil shared some figures about QEMU boot time impact by the number of CPU cores
    • Pre vCPU Init
    • Post vCPU Init (but pre-VGIC Init)
    • Post VGIC Init
    • Pre Linux Kernel Load
    • Post Kernel Load (But Pre SMBIOS setup)
  • LP: we need to converge and do some wrap up for proposal
    • Salil to share some details about how to get the figures
• Recording: link (password: *92a8xSE) 

Action items