From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4D469437.9050902@domain.hid> Date: Mon, 31 Jan 2011 11:51:35 +0100 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <1296469933.2214.35.camel@domain.hid> In-Reply-To: <1296469933.2214.35.camel@domain.hid> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-help] Is xenomai OK for early boot purpose ? List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Philippe Gerum Cc: xenomai@xenomai.org Philippe Gerum wrote: > On Mon, 2011-01-31 at 09:55 +0100, gryma biloy wrote: >> Hello, >> >> On a project running Linux on a beagle board, I'd like to add the >> following capabilities to my platform : >> - real time processes with periodic tasks (10ms, 100ms & 200 ms) and >> a low jitter (< 50 us) > > Kernel space apps then, likely. Userland apps (the recommended way) > probably have a larger worst-case jitter on this hardware, albeit still > below 100 us. Gilles? Las time I checked, latency measured on a 720MHz omap3 was around 55us with a 1ms period and 35us with a 100us period. > >> - early boot operations (i.e. being able to perform some tasks asap >> after a power on reset) >> >> I've searched for solutions over the net and Xenomai seems to be a >> possible candidate to fulfill >> these constraints. Can you please share your knowledge to confirm that >> Xenomai would make >> the job (especially on the early boot side) ? >> > > I don't see how Xenomai could directly help in any way for the early > boot goal. If you question is about whether Xenomai initializes fast > enough, and early enough during the linux boot process for kicking rt > applications as soon as possible, then the answer is yes, that should > do. Well, user-space applications will not get started before user-space is started, i.e. basically before root filesystem has been mounted and init is running. You could write your real-time application as the init application, but that would be kind of awkward. -- Gilles.