[RFC Patch 0/7] kernel: Introduce multikernel architecture support
From: Cong Wang To: linux-kernel-AT-vger.kernel.org Subject: [RFC Patch 0/7] kernel: Introduce multikernel architecture support Date: Thu, 18 Sep 2025 15:25:59 -0700 Message-ID: <[email protected]> Cc: pasha.tatashin-AT-soleen.com, Cong Wang , Cong Wang , Andrew Morton , Baoquan He , Alexander Graf , Mike Rapoport , Changyuan Lyu , kexec-AT-lists.infradead.org, linux-mm-AT-kvack.org
This patch series introduces multikernel architecture support, enabling multiple independent kernel instances to coexist and communicate on a single physical machine. Each kernel instance can run on dedicated CPU cores while sharing the underlying hardware resources. The multikernel architecture provides several key benefits: - Improved fault isolation between different workloads - Enhanced security through kernel-level separation - Better resource utilization than traditional VM (KVM, Xen etc.) - Potential zero-down kernel update with KHO (Kernel Hand Over) Architecture Overview: The implementation leverages kexec infrastructure to load and manage multiple kernel images, with each kernel instance assigned to specific CPU cores. Inter-kernel communication is facilitated through a dedicated IPI framework that allows kernels to coordinate and share information when necessary. Key Components: 1. Enhanced kexec subsystem with dynamic kimage tracking 2. Generic IPI communication framework for inter-kernel messaging 3. Architecture-specific CPU bootstrap mechanisms (only x86 so far) 4. Proc interface for monitoring loaded kernel instances Patch Summary: Patch 1/7: Introduces basic multikernel support via kexec, allowing multiple kernel images to be loaded simultaneously. Patch 2/7: Adds x86-specific SMP INIT trampoline for bootstrapping CPUs with different kernel instances. Patch 3/7: Introduces dedicated MULTIKERNEL_VECTOR for x86 inter-kernel communication. Patch 4/7: Implements generic multikernel IPI communication framework for cross-kernel messaging and coordination. Patch 5/7: Adds arch_cpu_physical_id() function to obtain physical CPU identifiers for proper CPU management. Patch 6/7: Replaces static kimage globals with dynamic linked list infrastructure to support multiple kernel images. Patch 7/7: Adds /proc/multikernel interface for monitoring and debugging loaded kernel instances. The implementation maintains full backward compatibility with existing kexec functionality while adding the new multikernel capabilities. IMPORTANT NOTES: 1) This is a Request for Comments (RFC) submission. While the core architecture is functional, there are numerous implementation details that need improvement. The primary goal is to gather feedback on the high-level design and overall approach rather than focus on specific coding details at this stage. 2) This patch series represents only the foundational framework for multikernel support. It establishes the basic infrastructure and communication mechanisms. We welcome the community to build upon this foundation and develop their own solutions based on this framework. 3) Testing has been limited to the author's development machine using hard-coded boot parameters and specific hardware configurations. Community testing across different hardware platforms, configurations, and use cases would be greatly appreciated to identify potential issues and improve robustness. Obviously, don't use this code beyond testing. This work enables new use cases such as running real-time kernels alongside general-purpose kernels, isolating security-critical applications, and providing dedicated kernel instances for specific workloads etc.. Signed-off-by: Cong Wang --- Cong Wang (7): kexec: Introduce multikernel support via kexec x86: Introduce SMP INIT trampoline for multikernel CPU bootstrap x86: Introduce MULTIKERNEL_VECTOR for inter-kernel communication kernel: Introduce generic multikernel IPI communication framework x86: Introduce arch_cpu_physical_id() to obtain physical CPU ID kexec: Implement dynamic kimage tracking kexec: Add /proc/multikernel interface for kimage tracking arch/powerpc/kexec/crash.c | 8 +- arch/x86/include/asm/idtentry.h | 1 + arch/x86/include/asm/irq_vectors.h | 1 + arch/x86/include/asm/smp.h | 7 + arch/x86/kernel/Makefile | 1 + arch/x86/kernel/crash.c | 4 +- arch/x86/kernel/head64.c | 5 + arch/x86/kernel/idt.c | 1 + arch/x86/kernel/setup.c | 3 + arch/x86/kernel/smp.c | 15 ++ arch/x86/kernel/smpboot.c | 161 +++++++++++++ arch/x86/kernel/trampoline_64_bsp.S | 288 ++++++++++++++++++++++ arch/x86/kernel/vmlinux.lds.S | 6 + include/linux/kexec.h | 22 +- include/linux/multikernel.h | 81 +++++++ include/uapi/linux/kexec.h | 1 + include/uapi/linux/reboot.h | 2 +- init/main.c | 2 + kernel/Makefile | 2 +- kernel/kexec.c | 103 +++++++- kernel/kexec_core.c | 359 ++++++++++++++++++++++++++++ kernel/kexec_file.c | 33 ++- kernel/multikernel.c | 314 ++++++++++++++++++++++++ kernel/reboot.c | 10 + 24 files changed, 1411 insertions(+), 19 deletions(-) create mode 100644 arch/x86/kernel/trampoline_64_bsp.S create mode 100644 include/linux/multikernel.h create mode 100644 kernel/multikernel.c -- 2.34.1