From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36437) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZMDNA-00029P-SM for qemu-devel@nongnu.org; Mon, 03 Aug 2015 06:53:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZMDN5-0006Ar-QS for qemu-devel@nongnu.org; Mon, 03 Aug 2015 06:53:36 -0400 Received: from relay.parallels.com ([195.214.232.42]:42959) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZMDN5-0005wM-HD for qemu-devel@nongnu.org; Mon, 03 Aug 2015 06:53:31 -0400 Received: from [10.255.249.46] (helo=mail.odin.com) by relay.parallels.com with esmtps (TLSv1.2:AES256-SHA:256) (Exim 4.85) (envelope-from ) id 1ZMD98-0004yy-L2 for qemu-devel@nongnu.org; Mon, 03 Aug 2015 13:39:06 +0300 From: Andrey Smetanin Message-ID: <55BF44AE.7020909@virtuozzo.com> Date: Mon, 3 Aug 2015 13:38:38 +0300 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Question: cpu_physical_memory_map() and atomic test and set bit pattern Reply-To: asmetanin@virtuozzo.com List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Hello, QEMU Developers! cpu_physical_memory_map() calls directly addess_space_map() which has comment "Use only for reads OR writes - not for read-modify-write operations." Why there is such restriction (only read or write access) in addess_space_map()/cpu_physical_memory_map() ? How to transparently atomically test and set bit of guest memory inside QEMU host? Is there any API for that pattern ? Or may I use cpu_physical_memory_map with is_write = 1 for that safely ? Thanks, Andrey