From owner-freebsd-hackers@FreeBSD.ORG Sat May 17 17:30:13 2008 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 052C9106564A for ; Sat, 17 May 2008 17:30:13 +0000 (UTC) (envelope-from mwm-keyword-freebsdhackers2.e313df@mired.org) Received: from mired.org (five.mired.org [66.92.153.75]) by mx1.freebsd.org (Postfix) with ESMTP id 83D8F8FC17 for ; Sat, 17 May 2008 17:30:12 +0000 (UTC) (envelope-from mwm-keyword-freebsdhackers2.e313df@mired.org) Received: (qmail 47811 invoked by uid 1001); 17 May 2008 13:30:38 -0400 Received: from bhuda.mired.org (bhuda [192.168.195.1]) by bhuda (tmda-ofmipd) with ESMTP; Sat, 17 May 2008 13:30:38 -0400 Date: Sat, 17 May 2008 13:30:37 -0400 Cc: freebsd-hackers@freebsd.org Message-ID: <20080517133037.3a3935db@bhuda.mired.org> In-Reply-To: <482E93C0.4070802@icyb.net.ua> References: <482E93C0.4070802@icyb.net.ua> Organization: Meyer Consulting X-Mailer: Claws Mail 3.4.0 (GTK+ 2.12.9; amd64-portbld-freebsd7.0) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Delivery-Agent: TMDA/1.1.12 (Macallan) From: Mike Meyer Subject: Re: rdmsr from userspace X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 17 May 2008 17:30:13 -0000 On Sat, 17 May 2008 11:13:52 +0300 Andriy Gapon wrote: > It seems that rdmsr instruction can be executed only at the highest > privilege level and thus is not permitted from userland. Maybe we should > provide something like Linux /dev/cpu/msr? > I don't like interface of that device, I think that ioctl approach would > be preferable in this case. > Something like create /dev/cpuN and allow some ioctls on it: > ioctl(cpu_fd, CPU_RDMSR, arg). > What do you think? Ok, this points directly at a question I've been wondering about, but haven't been able to find an answer in the google. I've been mucking about with general access to sysctl's (a sysctl plugin for gkrellm, and a python module for accessing sysctls), and with that hammer in my hand, the nail for this problem is obviously a dev.cpu.#.msr sysctl. Except that this would be harder to use from languages that don't provide direct access to libc functions than a file, with or without an ioctl (ioctl's are at at least POSIX, which is a functionality level a lot of languages aspire to), and also easier to manipulate with standard Unix tools in general. However, I thought I'd sense some hostility towards /dev/proc-like things from the freebsd community. Which is where my questions come in: Am I imagining that? If not, is there a real basis for it - and what would that be? Thanks, http://www.mired.org/consulting.html Independent Network/Unix/Perforce consultant, email for more information. O< ascii ribbon campaign - stop html mail - www.asciiribbon.org