From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1EKHhL-00013t-Kr for user-mode-linux-devel@lists.sourceforge.net; Tue, 27 Sep 2005 08:48:51 -0700 Received: from qproxy.gmail.com ([72.14.204.206]) by mail.sourceforge.net with esmtp (Exim 4.44) id 1EKHgz-0001WQ-Lm for user-mode-linux-devel@lists.sourceforge.net; Tue, 27 Sep 2005 08:48:51 -0700 Received: by qproxy.gmail.com with SMTP id f10so532534qba for ; Tue, 27 Sep 2005 08:48:19 -0700 (PDT) Message-ID: <3524bf1f050927070645b999bd@mail.gmail.com> From: Young Koh Reply-To: Young Koh MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Disposition: inline Subject: [uml-devel] a question about sigsetjmp() in copy_from/to_user() Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Tue, 27 Sep 2005 10:06:53 -0400 Content-Transfer-Encoding: 8bit To: user-mode-linux-devel@lists.sourceforge.net Hi, i have a question about copy_from/to_user() implementation in skas mode. as my understanding, when copy_from/to_user() is invoked, before the address translation happens, UML kernel calls sigsetjmp() to come back when there is a segmentation fault. and if there is, it seems that the system call an application triggered eventually returns EFAULT. then, it seems to me that sigsetjmp() is to catch the error when the application gave the invalid user space address. my question is, if so, shouldn't the error be caught when UML kernel translates the user space address to the kernel space address? i mean, UML kernel must know the valid memory regions and if the address is out of the valid regions, then it knows the address is invalid before UML tries to access the address. why should it use sigsetjmp() and let a segfault occur? Thank you in advance, -Young ------------------------------------------------------- This SF.Net email is sponsored by: Power Architecture Resource Center: Free content, downloads, discussions, and more. http://solutions.newsforge.com/ibmarch.tmpl _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel