From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56240) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YDGNB-0006pV-96 for qemu-devel@nongnu.org; Mon, 19 Jan 2015 12:44:22 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YDGN7-0002U0-99 for qemu-devel@nongnu.org; Mon, 19 Jan 2015 12:44:21 -0500 Received: from mail-qa0-x22f.google.com ([2607:f8b0:400d:c00::22f]:57907) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YDGN7-0002Tw-54 for qemu-devel@nongnu.org; Mon, 19 Jan 2015 12:44:17 -0500 Received: by mail-qa0-f47.google.com with SMTP id n8so24892888qaq.6 for ; Mon, 19 Jan 2015 09:44:14 -0800 (PST) Sender: Richard Henderson Message-ID: <54BD426A.5070107@twiddle.net> Date: Mon, 19 Jan 2015 09:44:10 -0800 From: Richard Henderson MIME-Version: 1.0 References: <1413910544-20150-1-git-send-email-greg.bellows@linaro.org> <1413910544-20150-6-git-send-email-greg.bellows@linaro.org> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v7 05/32] target-arm: make arm_current_el() return EL3 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell , Greg Bellows Cc: Sergey Fedorov , QEMU Developers , Fabian Aggeler , "Edgar E. Iglesias" On 01/19/2015 05:22 AM, Peter Maydell wrote: > Richard: do you have a feel for how expensive it is to > have lots and lots of mmu modes? I might be able to > merge "S EL1" with "NS EL1 stage 1+2" and ditto "S EL0" > with "NS EL0 stage1 + 2" but we'd need to do more TLB > flushing and it's not clear to me currently exactly > where the extra flushes would have to go... It's 10k per mmu mode, more or less. That's what you've got to memset (to -1) whenever a flush occurs. With the obvious mathematics wrt flush rate that implies. r~