From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <48039113.2000905@domain.hid> Date: Mon, 14 Apr 2008 13:14:59 -0400 From: Tomas Kalibera MIME-Version: 1.0 References: <4802A8F4.4090108@domain.hid> <4803073B.3060802@domain.hid> In-Reply-To: <4803073B.3060802@domain.hid> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-help] Interrupt propagation question List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: rpm@xenomai.org Cc: xenomai@xenomai.org Hi, so I've gone through the sources and made my guesses. When called from user space, rt_intr_create results in a kernel-space handler being installed using kernel-space rt_intr_create. The kernel handler only counts received interrupts, exiting as soon as the count is updated. The kernel handler is called with the interrupt disabled. On return, it uses the I_NOAUTOENA flag from the user space call to rt_intr_create. When the flag is set, the interrupts should stay disabled at hardware level unless explicitly enabled by application. If rt_intr_wait is called from user space, it blocks until interrupt count is >=1, then returns the interrupt count. Enabling/disabling interrupts has thus no direct impact on rt_intr_wait returning - if some interrupts are left to handle, rt_intr_wait will return even if the interrupt is disabled. As far as my guesses based on the code are correct, rt_intr_enable and rt_intr_disable called from user space should do end up in the interrupts being enabled/disabled at hardware level. A simple example however does not seem to follow this - I disable interrupts, do not enable it, and they're still received. Why could this be happening ? Is there a way to inquire if the interrupt is really disabled, at application level ? Tomas Philippe Gerum wrote: > Tomas Kalibera wrote: > >> Hi, >> >> I'm receiving interrupts in Xenomai user-domain using rt_intr_wait. What >> is the semantics of rt_intr_enable and rt_intr_disable ? And I_NOAUTOENA ? >> >> I used I_NOAUTOENA when calling rt_intr_create. I thought that after >> returning from rt_intr_wait, the interrupt would be disabled before I >> explicitly call rt_intr_enable. However, next call to rt_intr_wait >> happily returned with the next interrupt, as opposed to blocking >> indefinitely. Why ? Does rt_intr_wait automatically re-enable the >> interrupt ? >> >> I tried to intentionally loose interrupts - I called rt_intr_enable >> while handling an interrupt intentionally before making the hardware >> generate next one. Still, the next call to rt_intr_wait did return (the >> interrupt was not lost). How could this happen ? If interrupts are >> logged anyway, what the rt_intr_enable/disable does ? >> >> I read in the API documentation >> >> "Interrupt receipts are logged if they cannot be delivered immediately >> to some interrupt server task, so that a call to rt_intr_wait() >> >> might return immediately if an IRQ is already pending on entry of the >> service." >> >> How does Xenomai find out about this ? I mean, if a "interrupt server >> task" is not presently blocked in rt_intr_wait for a particular >> interrupt, how does Xenomai know that a task is actually an "interrupt >> server task" ? When does this association happen ? Does a call to >> rt_intr_create make Xenomai log interrupts for the domain from which >> rt_intr_create was called ? >> >> > > This call delivers interrupts to the Xenomai domain, only. > > For the rest, have a look at ksrc/skins/native/syscall.c, __rt_intr_wait, and > __rt_intr_handler. > > >> Thanks ! >> Tomas >> >> >> >> >> >> >> _______________________________________________ >> Xenomai-help mailing list >> Xenomai-help@domain.hid >> https://mail.gna.org/listinfo/xenomai-help >> >> > > >