Updating the summary to this because the old one no longer describes the goal of the session well enough. --- I'd like to propose a discussion of how CXL volatile memory device configuration is creating a complex memory initialization/allocation process. This is making it difficult for users to get "what they want". Example issues for discussion: - Linux-arch defined memory block size and alignment requirements - CXL as ZONE_NORMAL vs ZONE_MOVABLE impacts on memmap and performance - NUMA node and memory tier allocations, and new evolutions a) multiple NUMA-nodes per device b) confusing state of memory-tier component - cma and 1GB hugepage allocation from ZONE_MOVABLE on CXL Most of this complexity is being generated by how BIOS, ACPI, build, and boot config options interactions with each other. The best documented description of these interactions is: "Complicated, Subtle, and Scary". Having better documentation on "Linux Expectations for CXL Platforms" will help guide innovations in this space - but requires some agreement on limitations to keep existing components functional. This is becoming increasingly important as more CXL hardware is placed into production. The live session will not cover the full initialization process, which I've attempted to describe and discuss in [1][2][3][4][5][6][7][8]. The intent is to evolve this series into more explicit documentation for platform developers and help bridge the gap between maintainers that need background on "Why the heck does CXL need this?". [1] Section 0: ACPI Tables https://lore.kernel.org/linux-mm/Z8jORKIWC3ZwtzI4@gourry-fedora-PF4VCD3F/ [2] Section 0a: CFMWS and NUMA Flexibility https://lore.kernel.org/linux-mm/Z8u4GTrr-UytqXCB@gourry-fedora-PF4VCD3F/ [3] Section 1: BIOS, EFI, and Early Boot https://lore.kernel.org/linux-mm/Z6LKJZkcdjuit2Ck@gourry-fedora-PF4VCD3F/ [4] Section 2: The Drivers https://lore.kernel.org/linux-mm/Z6OMcLt3SrsZjgvw@gourry-fedora-PF4VCD3F/ [5] Section 2a: CXL Decoder Programming https://lore.kernel.org/linux-mm/Z8o2HfVd0P_tMhV2@gourry-fedora-PF4VCD3F/ [6] Section 3: Memory (block) Hotplug https://lore.kernel.org/linux-mm/Z7OWmDXEYhT0BB0X@gourry-fedora-PF4VCD3F/ [7] Section 4: Interleave https://lore.kernel.org/linux-mm/Z9DQnjPWbkjqrI9n@gourry-fedora-PF4VCD3F/ [8] Section 5: Page Allocation https://lore.kernel.org/linux-mm/Z9Ogp9fCEPoORfnh@gourry-fedora-PF4VCD3F/ ~Gregory
