From owner-freebsd-hackers@freebsd.org Mon Jan 16 08:49:21 2017 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id E1514CB1980; Mon, 16 Jan 2017 08:49:21 +0000 (UTC) (envelope-from aijazbaig1@gmail.com) Received: from mail-wm0-x22e.google.com (mail-wm0-x22e.google.com [IPv6:2a00:1450:400c:c09::22e]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 7717417F7; Mon, 16 Jan 2017 08:49:21 +0000 (UTC) (envelope-from aijazbaig1@gmail.com) Received: by mail-wm0-x22e.google.com with SMTP id f73so29182971wmf.1; Mon, 16 Jan 2017 00:49:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=8s/68QNRCN11+Bsk89IqMlROQYvJwcEM6Qt+bNy+G+g=; b=M3gURCAiVx/b1VzinSsZ/gTB9Cvtnoyv0xfTkB3Wj4ybNSwHP7Og7fgWeVOz1gwkBV DeEzIKUn7kjKuFiBAkbciO3p4JEWalFfFQgUZdK+DaKSnuQ4TU/JnFNIBmwoh700UIdR m+T15FhiDTuGDfmo6JpcAh2h8kAcJszNvXO5i0isptFhiijrI++fdFYhsycffgY85orN 4H1FcnjuEgzhGzBUJkUww+Y52WCDiaW70DLKQGsmyiA2Jd+6lqr5khuFFdYBJ7eL6Ygl E8Fs+p1dOsGD6nxUNg9+dr4ojca7kIQxSvUheFEoOHROVSdiGj8CPXzi4SxGO0gSBo9v im3Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=8s/68QNRCN11+Bsk89IqMlROQYvJwcEM6Qt+bNy+G+g=; b=fYDdiwE6Teq+bVSdjr1c23pk6hb5yRPvs+ZWPioNIEQ5mtDIQGAfQciA8S3eD2p043 yHyylZUsepMdoW6m/KMizq1ebrXwHC3lbN/uwkIJUuF8Jjrd3naL3HWzSjooIN1eUt1j kF6lCie6GWpUVgybXjz0DIodvlo/VwmqvPuzTr+hjFBKmAJUP+uCjByDom0q9ElYvAKm c6nxM6pVTciZqcq9sCghXprEs7xQLxtUkao8KIpKtTqFnuj6Pw6EI1aXUGI990ecDkLS KQ017tS3gMm7iURD2HP6WMFp2xwxfYmm0n/95rAhAKpcaKKBi4R0AJe92wRQomrMg7PL OI/g== X-Gm-Message-State: AIkVDXIU7GpDXZ5LENWSnZXU44W5n+p8It74FZyYOLhBoLdXvS29zuzZjREGv4YBnnkPrzvKwKD7giCu/apWew== X-Received: by 10.28.220.135 with SMTP id t129mr12474397wmg.38.1484556558922; Mon, 16 Jan 2017 00:49:18 -0800 (PST) MIME-Version: 1.0 Received: by 10.195.12.46 with HTTP; Mon, 16 Jan 2017 00:49:18 -0800 (PST) In-Reply-To: <20170116071105.GB4560@eureka.lemis.com> References: <20170116071105.GB4560@eureka.lemis.com> From: Aijaz Baig Date: Mon, 16 Jan 2017 14:19:18 +0530 Message-ID: Subject: Re: Understanding the rationale behind dropping of "block devices" To: "Greg 'groggy' Lehey" Cc: FreeBSD Hackers , freebsd-scsi@freebsd.org Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.23 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 16 Jan 2017 08:49:22 -0000 Oh yes I was actually running an old release inside a VM and yes I had changed the device names myself while jotting down notes (to give it a more descriptive name like what the OSX does). So now I've checked it on a recent release and yes there is indeed no block device. root@bsd-client:/dev # gpart show => 34 83886013 da0 GPT (40G) 34 1024 1 freebsd-boot (512K) 1058 58719232 2 freebsd-ufs (28G) 58720290 3145728 3 freebsd-swap (1.5G) 61866018 22020029 - free - (10G) root@bsd-client:/dev # ls -lrt da* crw-r----- 1 root operator 0x4d Dec 19 17:49 da0p1 crw-r----- 1 root operator 0x4b Dec 19 17:49 da0 crw-r----- 1 root operator 0x4f Dec 19 23:19 da0p3 crw-r----- 1 root operator 0x4e Dec 19 23:19 da0p2 So this shows that I have a single SATA or SAS drive and there are apparently 3 partitions ( or is it four?? Why does it show unused space when I had used the entire disk?) Nevertheless my question still holds. What does 'removing support for block device' mean in this context? Was what I mentioned earlier with regards to my understanding correct? Viz. all disk devices now have a character (or raw) interface and are no longer served via the "page cache" but rather the "buffer cache". Does that mean all disk accesses are now direct by passing the file system?? On Mon, Jan 16, 2017 at 12:41 PM, Greg 'groggy' Lehey wrote: > On Monday, 16 January 2017 at 8:10:16 +0530, Aijaz Baig wrote: > > > > But when I check the disk nodes under /dev I get this > > [CODE]ls -l /dev/*disk0 > > brw-r----- 1 root operator 14, 0 Jan 2 09:39 /dev/disk0 > > crw-r----- 1 root operator 14, 0 Jan 2 09:39 /dev/rdisk0[/CODE] > > Are you sure that this is FreeBSD? The naming convention looks more > like Mac OS, though the major device number doesn't match. FreeBSD > has been through a number of disk naming conventions, but I'm pretty > sure that we never had anything as straightforward as 'disk'. > > > what was there earlier in FreeBSD before 'block device support' was > > dropped? > > Apart from the name, things used to look similar. Here a quote from > "The Complete FreeBSD", written some time at the end of the last > century: > > crw-r----- 1 root operator 3, 131072 Oct 31 19:59 /dev/rwd0s1a > brw-r----- 1 root operator 0, 131072 Oct 31 19:59 /dev/wd0s1a > > The minor number included partition encoding, thus the large number. > > Greg > -- > Sent from my desktop computer. > Finger grog@FreeBSD.org for PGP public key. > See complete headers for address and phone numbers. > This message is digitally signed. If your Microsoft mail program > reports problems, please read http://lemis.com/broken-MUA > -- Best Regards, Aijaz Baig