On Wed, Mar 11, 2020 at 10:42 PM tip-bot2 for Hans de Goede <tip-bot2@xxxxxxxxxxxxx> wrote: > select GENERIC_GETTIMEOFDAY > select GENERIC_VDSO_TIME_NS > select GUP_GET_PTE_LOW_HIGH if X86_PAE > + select HARDIRQS_SW_RESEND Just help me understand the semantics of this thing... According to the text in KConfig: # Tasklet based software resend for pending interrupts on enable_irq() config HARDIRQS_SW_RESEND bool According to commit a4633adcdbc15ac51afcd0e1395de58cee27cf92 [PATCH] genirq: add genirq sw IRQ-retrigger Enable platforms that do not have a hardware-assisted hardirq-resend mechanism to resend them via a softirq-driven IRQ emulation mechanism. so when enable_irq() is called, if the IRQ is already asserted, it will be distributed in the form of a software irq? OK I give up I don't understand the semantics of this thing. Maybe it's because I think of a register where the IRQ line is just a level IRQ bit thing that stays high as long as the IRQ is not handled. So I suppose it is for any type of transient IRQ such as edge triggered that happened before the system came back online entirely and now the only remnant of it is a bit in the irchip status register? I see that ARM and ARM64 simply just select this. What happens if you do that and why is x86 not selecting it in general? Explain it to me and I promise to patch kernel/irq/Kconfig with the explanation so you don't have to give it again. Yours, Linus Walleij
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