Messages in this thread | | | Date | Tue, 28 Sep 1999 13:33:55 -0400 (EDT) | From | "Richard B. Johnson" <> | Subject | Re: SA_INTERRUPT |
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On Tue, 28 Sep 1999, Bradley D. LaRonde wrote:
> What is the current wisdom on SA_INTERRUPT? > > A comment in signal.h about it says "dummy -- ignored". Elsewhere it says > that "SA_INTERRUPT is a no-op left for historical reasons". > > That certainly doesn't seem to be the case in irq.c. It appears to be used > like this: if SA_INTERRUPT isn't set, enable interrupts during interrupt > handling. > > So what is this flag for? How, when, and why should it be used? > > Thanks. > > Regards, > Brad
It is unfortunate that the same #define is used for signals and for kernel interrupts. They are not related. As you noticed,i SA_INTERRUPT with respect to signals is a no-op since it doesn't change the nature of signals. However, with respect to IRQ handling within the kernel, it does enable interrupts before your possible bottom-half ISR is checked to see if it exists and executed. See line 726 (about) in ../arch/i386/kernel/irq.c
Cheers, Dick Johnson **** FILE SYSTEM WAS MODIFIED **** Penguin : Linux version 2.3.13 on an i686 machine (400.59 BogoMips). Warning : It's hard to remain at the trailing edge of technology.
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