From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [Adeos-main] adeos_enter/exit_syscall From: Philippe Gerum Reply-To: rpm@xenomai.org In-Reply-To: <0C53F2DBA565D411885300508B553B5204CCEAE9@domain.hid> References: <0C53F2DBA565D411885300508B553B5204CCEAE9@domain.hid> Content-Type: text/plain Message-Id: <1091658284.618.149.camel@domain.hid> Mime-Version: 1.0 Date: Thu, 05 Aug 2004 00:24:44 +0200 Content-Transfer-Encoding: 7bit Sender: adeos-main-admin@domain.hid Errors-To: adeos-main-admin@domain.hid List-Help: List-Post: List-Subscribe: , List-Id: General discussion about Adeos List-Unsubscribe: , List-Archive: To: aaron durbin Cc: "'adeos-main@gna.org'" On Thu, 2004-08-05 at 00:16, aaron durbin wrote: > I have a question concerning the adeos_enter_syscall routine. Is there > normally event monitors for syscall entry (SYSCALL_PROLOGUE)? Not normally when no domain is loaded. The Linux domain by itself does not intercept (its own) syscalls. But other domains might want this (RTAI does). > If so and > handle_event returns non-zero then one automatically restores the registers > and returns w/o calling the system call. Doesn't this destroy the call? > It prevents its execution by the Linux kernel actually. Think of a more prioritary (in the sense higher in the pipeline than Linux) that wants to intercept some specific syscalls issued by regular Linux apps, and provides a replacement for them. In such a case, you might not want the original syscall to be handled by Linux too; so you make sure that it is not propagated to Linux -- this translates in having handle_event return non-zero (because adeos_propagate_event is not called for the said syscall in the upper domain handler). > -Aaron > > _______________________________________________ > Adeos-main mailing list > Adeos-main@domain.hid > https://mail.gna.org/listinfo/adeos-main -- Philippe.