kernel/arch/um/os-Linux/internal.h, branch linux-rolling-stable

um: Add initial SMP support

2025-10-27T15:41:15Z

Add initial symmetric multi-processing (SMP) support to UML. With this support enabled, users can tell UML to start multiple virtual processors, each represented as a separate host thread. In UML, kthreads and normal threads (when running in kernel mode) can be scheduled and executed simultaneously on different virtual processors. However, the userspace code of normal threads still runs within their respective single-threaded stubs. That is, SMP support is currently available both within the kernel and across different processes, but still remains limited within threads of the same process in userspace. Signed-off-by: Tiwei Bie Link: https://patch.msgid.link/20251027001815.1666872-6-tiwei.bie@linux.dev Signed-off-by: Johannes Berg

um: Determine sleep based on need_resched()

2025-10-27T15:41:15Z

With SMP and NO_HZ enabled, the CPU may still need to sleep even if the timer is disarmed. Switch to deciding whether to sleep based on pending resched. Additionally, because disabling IRQs does not block SIGALRM, it is also necessary to check for any pending timer alarms. This is a preparation for adding SMP support. Signed-off-by: Tiwei Bie Link: https://patch.msgid.link/20251027001815.1666872-4-tiwei.bie@linux.dev Signed-off-by: Johannes Berg

um: Implement kernel side of SECCOMP based process handling

2025-06-02T13:17:19Z

This adds the kernel side of the seccomp based process handling. Co-authored-by: Johannes Berg Signed-off-by: Benjamin Berg Signed-off-by: Benjamin Berg Link: https://patch.msgid.link/20250602130052.545733-6-benjamin@sipsolutions.net Signed-off-by: Johannes Berg

um: Add an internal header shared among the user code

2024-04-30T12:16:44Z

Move relevant declarations to this header. This will address below -Wmissing-prototypes warnings: arch/um/os-Linux/elf_aux.c:26:13: warning: no previous prototype for ‘scan_elf_aux’ [-Wmissing-prototypes] arch/um/os-Linux/mem.c:213:13: warning: no previous prototype for ‘check_tmpexec’ [-Wmissing-prototypes] arch/um/os-Linux/skas/process.c:107:6: warning: no previous prototype for ‘wait_stub_done’ [-Wmissing-prototypes] Signed-off-by: Tiwei Bie Signed-off-by: Richard Weinberger

um: Switch clocksource to hrtimers

2015-11-06T21:54:49Z

UML is using an obsolete itimer call for all timers and "polls" for kernel space timer firing in its userspace portion resulting in a long list of bugs and incorrect behaviour(s). It also uses ITIMER_VIRTUAL for its timer which results in the timer being dependent on it running and the cpu load. This patch fixes this by moving to posix high resolution timers firing off CLOCK_MONOTONIC and relaying the timer correctly to the UML userspace. Fixes: - crashes when hosts suspends/resumes - broken userspace timers - effecive ~40Hz instead of what they should be. Note - this modifies skas behavior by no longer setting an itimer per clone(). Timer events are relayed instead. - kernel network packet scheduling disciplines - tcp behaviour especially under load - various timer related corner cases Finally, overall responsiveness of userspace is better. Signed-off-by: Thomas Meyer Signed-off-by: Anton Ivanov [rw: massaged commit message] Signed-off-by: Richard Weinberger

um: pass siginfo to guest process

2012-08-01T22:49:17Z

UML guest processes now get correct siginfo_t for SIGTRAP, SIGFPE, SIGILL and SIGBUS. Specifically, si_addr and si_code are now correct where previously they were si_addr = NULL and si_code = 128. Signed-off-by: Martin Pärtel Signed-off-by: Richard Weinberger

um: start switching the references to host mcontext_t to its userland type

2011-11-02T13:14:59Z

Signed-off-by: Al Viro Signed-off-by: Richard Weinberger