On 2019-08-15 09:52:56 [-0400], Paul Thomas wrote: > > > Emergency messages are not involved here. You can see at 84239098us that > > Right, we don't have that. Let me boot my arm64, print something and > > check how it goes… > Thanks! Nothing too crazy is happening with printk in my setup. Mostly > I just see systemd messages like this: > [55458.630872] systemd-journald[1072]: Sent WATCHDOG=1 notification. > [55578.632076] systemd-journald[1072]: Sent WATCHDOG=1 notification. so that explains it. Here, I have | printk-106 [001] ....111 610.156787: pl011_read <-pl011_console_putchar | printk-106 [001] d..h211 610.156788: irq_find_mapping <-__handle_domain_irq … | printk-106 [001] dN.h211 610.156812: preempt_count_sub <-irq_exit | printk-106 [001] .N..111 610.156813: pl011_read <-pl011_console_putchar | cyclictest-802 [001] d...3.. 610.156815: finish_task_switch <-__schedule so it seems to works but I *think* that at 610.156813 shouldn't be there and it should switch to cyclictest. But if it is the broken irq-exit path then this should fix it: diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 63c6960262861..27a16c2711981 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -649,13 +649,7 @@ alternative_if ARM64_HAS_IRQ_PRIO_MASKING alternative_else_nop_endif cbz x24, 1f // (need_resched + count) == 0 - cbnz w24, 2f // count != 0 - - ldr w24, [tsk, #TSK_TI_PREEMPT_LAZY] // get preempt lazy count - cbnz w24, 2f // preempt lazy count != 0 - - ldr x0, [tsk, #TSK_TI_FLAGS] // get flags - tbz x0, #TIF_NEED_RESCHED_LAZY, 2f // needs rescheduling? + b 2f // count != 0 1: bl preempt_schedule_irq // irq en/disable is done inside 2: > -Paul Sebastian
