Apparently a duplicate of https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1873315
-- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to lightdm in Ubuntu. https://bugs.launchpad.net/bugs/1874020 Title: Jack clients cannot use real-time scheduling with kernel 5.4.0-25-generic Status in lightdm package in Ubuntu: New Bug description: With kernels 5.4.0-24-generic and 5.4.0-25-generic Jack client applications can no longer use real-time scheduling. Kernel 5.4.0-23-generic works. For example starting guitarix or ardour produces the following logs on stderr: Cannot use real-time scheduling (RR/5)(1: Operation not permitted) JackClient::AcquireSelfRealTime error The following is a strace from an older (working) kernel: sched_get_priority_min(SCHED_FIFO) = 1 sched_get_priority_max(SCHED_FIFO) = 99 sched_get_priority_min(SCHED_FIFO) = 1 sched_get_priority_max(SCHED_FIFO) = 99 mmap(NULL, 8392704, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7fd5c307c000 mprotect(0x7fd5c307d000, 8388608, PROT_READ|PROT_WRITE) = 0 clone(child_stack=0x7fd5c387b9f0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CL ONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tid=[47564], tls=0x7fd5c3 87c700, child_tidptr=0x7fd5c387c9d0) = 47564 sched_setscheduler(47564, SCHED_FIFO, [1]) = 0 Compare against an strace with an affected kernel: sched_get_priority_min(SCHED_FIFO) = 1 sched_get_priority_max(SCHED_FIFO) = 99 sched_get_priority_min(SCHED_FIFO) = 1 sched_get_priority_max(SCHED_FIFO) = 99 mmap(NULL, 8392704, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7f8d827ee000 mprotect(0x7f8d827ef000, 8388608, PROT_READ|PROT_WRITE) = 0 clone(child_stack=0x7f8d82fed9f0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CL ONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tid=[21592], tls=0x7f8d82 fee700, child_tidptr=0x7f8d82fee9d0) = 21592 sched_setscheduler(21592, SCHED_FIFO, [1]) = -1 EPERM (Operation not permitted) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/1874020/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp