From: Tiwei Bie <tiwei....@antgroup.com>
This is a follow-up to the discussion in this thread:
https://lore.kernel.org/linux-um/20250711065021.2535362-4-tiwei....@linux.dev/
Currently, this is still a PoC and requires further improvements.
I performed a kernel build test inside UML with 8 virtual CPUs enabled:
$ tar xf linux-6.15.tar.gz
$ cd linux-6.15
$ make ARCH=um defconfig > /dev/null
$ time make ARCH=um -j16 > /dev/null
real 6m2.529s
user 43m37.665s
sys 0m34.585s
$ ./linux --version
6.15.0
$ cat /proc/cpuinfo | grep -c '^processor'
8
Here are some steps to try out SMP support in UML:
1. Build UML with CONFIG_SMP=y and, for example, CONFIG_NR_CPUS=8.
2. Launch a UML instance with, for example, 8 virtual CPUs.
$ ./linux mem=16G ncpus=8 nohz=n seccomp=on init=/bin/sh \
ubd0=$your_rootfs_image
This patchset depends on the following patchset:
https://lore.kernel.org/linux-um/20250711065021.2535362-1-tiwei....@linux.dev/
Tiwei Bie (4):
um: Stop tracking virtual CPUs via mm_cpumask()
um: Remove unused cpu_data and current_cpu_data macros
um: vdso: Implement __vdso_getcpu() via syscall
um: Add SMP support
arch/um/Kconfig | 28 ++-
arch/um/include/asm/Kbuild | 3 +
arch/um/include/asm/current.h | 5 +-
arch/um/include/asm/hardirq.h | 24 ++-
arch/um/include/asm/irqflags.h | 4 +-
arch/um/include/asm/mmu.h | 7 +
arch/um/include/asm/mmu_context.h | 11 --
arch/um/include/asm/pgtable.h | 2 +
arch/um/include/asm/processor-generic.h | 8 +-
arch/um/include/asm/smp.h | 31 +++-
arch/um/include/asm/spinlock.h | 8 +
arch/um/include/linux/smp-internal.h | 8 +
arch/um/include/linux/time-internal.h | 3 +
arch/um/include/shared/kern_util.h | 2 +
arch/um/include/shared/longjmp.h | 3 +-
arch/um/include/shared/os.h | 12 +-
arch/um/include/shared/smp.h | 14 ++
arch/um/kernel/Makefile | 1 +
arch/um/kernel/irq.c | 31 +++-
arch/um/kernel/ksyms.c | 2 +-
arch/um/kernel/mem.c | 2 +
arch/um/kernel/process.c | 19 +-
arch/um/kernel/skas/mmu.c | 16 +-
arch/um/kernel/smp.c | 223 ++++++++++++++++++++++++
arch/um/kernel/time.c | 48 +++--
arch/um/kernel/tlb.c | 5 +-
arch/um/kernel/trap.c | 2 +-
arch/um/kernel/um_arch.c | 60 ++++++-
arch/um/os-Linux/Makefile | 4 +-
arch/um/os-Linux/file.c | 72 ++++++--
arch/um/os-Linux/main.c | 5 +-
arch/um/os-Linux/process.c | 15 ++
arch/um/os-Linux/signal.c | 16 +-
arch/um/os-Linux/skas/process.c | 1 +
arch/um/os-Linux/smp.c | 44 +++++
arch/um/os-Linux/start_up.c | 3 +
arch/um/os-Linux/time.c | 29 +--
arch/um/os-Linux/user_syms.c | 5 +
arch/x86/um/vdso/um_vdso.c | 18 +-
39 files changed, 695 insertions(+), 99 deletions(-)
create mode 100644 arch/um/include/asm/spinlock.h
create mode 100644 arch/um/include/linux/smp-internal.h
create mode 100644 arch/um/include/shared/smp.h
create mode 100644 arch/um/kernel/smp.c
create mode 100644 arch/um/os-Linux/smp.c
--
2.34.1
