Messages in this thread | | | Date | Thu, 11 Aug 2005 23:13:13 +0800 | From | Coywolf Qi Hunt <> | Subject | Re: Need help in understanding x86 syscall |
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On 8/11/05, Steven Rostedt <rostedt@goodmis.org> wrote: > On Thu, 2005-08-11 at 10:04 -0400, linux-os (Dick Johnson) wrote: > > Every interrupt software, or hardware, results in the branched > > procedure being executed with the interrupts OFF. That's why > > one of the first instructions in the kernel entry for a syscall > > is 'sti' to turn them back on. Look at entry.S, line 182. This > > occurs any time a trap occurs as well (Page 26-168, i486 > > Programmer's reference manual). FYI, this is helpful when > > designing/debugging complex interrupt-service routines since > > you can execute the interrupt with a software 'INT' instruction > > (with the correct offset from the IRQ you are using). The software > > doesn't 'know' where the interrupt came from, HW or SW. > > I'm looking at 2.6.13-rc6-git1 line 182 of entry.S and I don't see it. > Must be a different kernel. > > According to the documentation that I was looking at, a trap in x86 does > _not_ turn off interrupts. > ... > > I don't see a sti here. > > -- Steve
He is RBJ, Richard B. Johnson, the LKML defacto official troll.
-- Coywolf Qi Hunt http://ahbl.org/~coywolf/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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