From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 27 Feb 2015 21:50:04 +0100 From: Gilles Chanteperdrix Message-ID: <20150227205004.GO434@hermes.click-hack.org> References: <54F0CF9E.1040707@siemens.com> <20150227202453.GK434@hermes.click-hack.org> <54F0D584.1030307@siemens.com> <54F0D7E9.2080209@siemens.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54F0D7E9.2080209@siemens.com> Subject: Re: [Xenomai] [RFC] Consolidated exception prologue/epiloge for x86 and ARM List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: Xenomai On Fri, Feb 27, 2015 at 09:47:37PM +0100, Jan Kiszka wrote: > On 2015-02-27 21:37, Jan Kiszka wrote: > > On 2015-02-27 21:24, Gilles Chanteperdrix wrote: > >> On Fri, Feb 27, 2015 at 09:12:14PM +0100, Jan Kiszka wrote: > >>> Hi, > >>> > >>> just pushed a first implementation of the general model that I proposed > >>> for exception handling. You can find it at > >>> > >>> http://git.xenomai.org/ipipe-jki.git/log/?h=queues/trap-rework > >> > >> NACK. The ARM implementation is broken, re-enabling hardware irqs > >> before stalling root is wrong. > > > > Ok, will adjust. > > But I need to think about this again first. It seems we are doing this > for ages on x86, and I need to understand why it could be a problem on > ARM. Can you provide an example that would breaks? You are creating a point where a Linux irq can happen which does not exist on the mainline kernel. If you do: local_irq_save(flags); hard_local_irq_enable(); There is no way a Linux interrupt can squeeze in. (I mean in the case of exception over root domamin, in the case of an exception over head, irqs are enabled anyway). -- Gilles.