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Date: Mon, 25 Sep 2006 19:05:21 +0200 From: Arnd Bergmann <arnd@...db.de> To: Aubrey <aubreylee@...il.com> Cc: "Luke Yang" <luke.adi@...il.com>, linux-kernel@...r.kernel.org, "Andrew Morton" <akpm@...l.org> Subject: Re: [PATCH 1/4] Blackfin: arch patch for 2.6.18 On Monday 25 September 2006 17:39, Aubrey wrote: > 1) Timer interrupt will call do_irq(), then return_from_int(). > > 2) return_from_int() will check if there is interrupt pending or > signal pending, if so, it will call schedule_and_signal_from_int(). > > 3) schedule_and_signal_from_int() will jump to resume_userspace() > > 4) resume_userspace() will call _schedule to run the user task. I have a little trouble reading your assembly code, but your return_from_int() function should normally not call schedule_and_signal_from_int() when the interrupt happened in kernel context (like in the idle function): + /* if not return to user mode, get out */ + p2.l = lo(IPEND); + p2.h = hi(IPEND); + r0 = [p2]; + r1 = 0x17(Z); + r2 = ~r1; + r2.h = 0; + r0 = r2 & r0; + r1 = 1; + r1 = r0 - r1; + r2 = r0 & r1; + cc = r2 == 0; + if !cc jump 2f; This looks a lot like you user_mode() function, so you jump over schedule_and_signal_from_int() here. What you described would be a preemptive kernel (CONFIG_PREEMPT), but you clearly don't have that enabled. Arnd <>< - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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