From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:32820) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YsEkb-0006lZ-IS for qemu-devel@nongnu.org; Tue, 12 May 2015 14:17:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YsEkY-0003il-2G for qemu-devel@nongnu.org; Tue, 12 May 2015 14:17:53 -0400 Received: from mail-wi0-x22e.google.com ([2a00:1450:400c:c05::22e]:36107) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YsEkX-0003i6-Rd for qemu-devel@nongnu.org; Tue, 12 May 2015 14:17:49 -0400 Received: by wizk4 with SMTP id k4so165854398wiz.1 for ; Tue, 12 May 2015 11:17:48 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <555243C8.30602@redhat.com> Date: Tue, 12 May 2015 20:17:44 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] when does a target frontend need to use gen_io_start()/gen_io_end() ? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell , QEMU Developers Cc: Pavel Dovgaluk , Richard Henderson On 12/05/2015 17:32, Peter Maydell wrote: > In order for -icount to work, it's important for the target > translate.c code to correctly bracket any generated code which > can "do I/O" with gen_io_start()/gen_io_end() calls. But > does anybody know exactly what the criteria are here for this? > It would be nice if we could document this in a comment in > gen_icount.h -- I'm happy to write one up if somebody will just > tell me what the right answer is :-) It's any instruction that can cause an icount read, typically through QEMU_CLOCK_VIRTUAL or cpu_get_ticks(). Paolo