From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4FDDE5DC.4030608@xenomai.org> Date: Sun, 17 Jun 2012 16:12:44 +0200 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <20120611141444.GU32727@csclub.uwaterloo.ca> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai] the Linux kernel and operating system List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: ali hagigat Cc: xenomai@xenomai.org On 06/17/2012 02:55 PM, ali hagigat wrote: > I think SMI needs some initialization from BIOS and then Linux kernel. > The Linux kernel has some CONFIG_ variables to disable/enable SMI. Last time I checked, the linux kernel did not have such CONFIG_ variables, which is why xenomai adds them. > In theory a motherboard can be built to generate SMI without the > software help. But I think OEMs do not build such a board. So I think > an x86 PC hard real time system is possible for today's PCs. > > Please correct me if I am wrong. An SMI is an interrupt, so, there must be software to handle the SMI, so, no, a motherboard can not be built to generate SMI without software help. Intel chipsets provide a register to disable SMIs, but also provide a register to lock usage of the first register. So yes, there are some PC today that you can not use for real-time. Unless, of course, you are ready to use your own BIOS instead of the one provided by the hardware vendor, or your hardware vendor is willing to change the BIOS. -- Gilles.