Date: Thu, 14 Apr 2016 14:48:39 +0200 (CEST) From: =?ISO-8859-1?Q?Trond_Endrest=F8l?= <Trond.Endrestol@fagskolen.gjovik.no> To: Aleksander Alekseev <afiskon@devzen.ru> Cc: freebsd-hackers@freebsd.org Subject: Re: A few stupid questions regarding MBR and boot0 Message-ID: <alpine.BSF.2.20.1604141444310.14591@mail.fig.ol.no> In-Reply-To: <20160414153627.7fc50247@fujitsu> References: <20160414144849.7a08b1db@fujitsu> <alpine.BSF.2.20.1604141353310.14591@mail.fig.ol.no> <20160414153627.7fc50247@fujitsu>
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On Thu, 14 Apr 2016 15:36+0300, Aleksander Alekseev wrote: > Hello, Trond > > Thanks for your replies. NP. > > > 1) If I understand correctly first 512 bytes of /dev/ad0 > > > and /boot/boot0 file should match, but they don't: > > > > > > http://afiskon.ru/s/31/665dc9755c_mbr.txt > > > > The MBR consists of two parts, the bootcode and the partition table. > > Any discrepancies is generally due to the partition table being zero > > in /boot/boot0 and realistic data stored in block 0. > > Yes, but if I'm not mistaken partition table starts only at 0x1be. But > in my case data is not just slightly different in last few bytes. Its > not the same at all. > > > BTW, check out /boot/mbr. > > OK, this looks like something I have on ad0. But this file is not > mentioned in corresponding chapters of Handbook [1] or Architecture > Handbook [2]. Besides Architecture Handbook clearly states: > > """ > Indeed, boot0 /is/ the MBR. > """ > > If /boot/boot0 is MBR then what is /boot/mbr? Current version of > Handbook mentions it twice in 18.3.2 and doesn't exactly explains what > this file is for. According to FreeBSD 8.4 Handbook [3]: > > """ > By default, the MBR installed by fdisk(8) is such an MBR and is based > on /boot/mbr. > """ fdisk(8) is an outdated tool. gpart(8) is the current tool. > Do I right understand that current version of Handbook is wrong > regarding: > > """ > The MBR installed by the FreeBSD installer is based on /boot/boot0. > """ > > ... and in fact boot0 is only used in dual-boot case? It could be. I'm not a committer, merely a user. > BTW `cd sys/boot/i386/mbr && make` works as expected. > > > I have never attempted to build the FreeBSD sources outside /usr/src. > > The advice below might be plain wrong. > > > > Try: > > > > cd sys/boot/i386/boot0 > > make clean > > make OBJDIR=/usr/home/eax/freebsd-obj obj > > make OBJDIR=/usr/home/eax/freebsd-obj all > > > > If you want it installed, run > > > > make OBJDIR=/usr/home/eax/freebsd-obj install > > > > Doesn't work: > > ``` > $ make OBJDIR=/usr/home/eax/freebsd-obj obj > mkdir: /usr/obj/usr: Permission denied > *** Error code 1 > > Stop. > make: stopped in /usr/home/eax/freebsd-src/sys/boot/i386/boot0 > ``` > > I also tried `OBJDIR=... make`. Naturally I could try `sudo make ...` > but if I'm not wrong boot0 doesn't have any dependencies, it's a > reasonably simple assembly program. Try: make MAKEOBJDIRPREFIX=/usr/home/eax/freebsd-obj xxx That should place the object tree in /usr/home/eax/freebsd-obj and avoid polluting the source tree. > [1]https://www.freebsd.org/doc/handbook/boot-introduction.html > [2]https://www.freebsd.org/doc/en/books/arch-handbook/boot-boot0.html > [3]https://docs.freebsd.org/doc/8.4-RELEASE/share/doc/freebsd/handbook/boot-introduction.html -- +-------------------------------+------------------------------------+ | Vennlig hilsen, | Best regards, | | Trond Endrestøl, | Trond Endrestøl, | | IT-ansvarlig, | System administrator, | | Fagskolen Innlandet, | Gjøvik Technical College, Norway, | | tlf. mob. 952 62 567, | Cellular...: +47 952 62 567, | | sentralbord 61 14 54 00. | Switchboard: +47 61 14 54 00. | +-------------------------------+------------------------------------+ From owner-freebsd-hackers@freebsd.org Thu Apr 14 12:54:40 2016 Return-Path: <owner-freebsd-hackers@freebsd.org> 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 05257B0E858 for <freebsd-hackers@mailman.ysv.freebsd.org>; Thu, 14 Apr 2016 12:54:40 +0000 (UTC) (envelope-from afiskon@devzen.ru) Received: from relay14.nicmail.ru (relay14.nicmail.ru [195.208.3.99]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id AFA7717C3 for <freebsd-hackers@freebsd.org>; Thu, 14 Apr 2016 12:54:39 +0000 (UTC) (envelope-from afiskon@devzen.ru) Received: from [109.70.25.225] (port=55695 helo=fujitsu) by f19.mail.nic.ru with esmtp (Exim 5.55) (envelope-from <afiskon@devzen.ru>) id 1aqgn5-000PEC-9h; Thu, 14 Apr 2016 15:54:35 +0300 Received: from [93.174.131.138] (account afiskon@devzen.ru HELO fujitsu) by proxy03.mail.nic.ru (Exim 5.55) with id 1aqgn4-0004A6-QI; Thu, 14 Apr 2016 15:54:34 +0300 Date: Thu, 14 Apr 2016 15:53:57 +0300 From: Aleksander Alekseev <afiskon@devzen.ru> To: Trond =?UTF-8?B?RW5kcmVzdMO4bA==?= <Trond.Endrestol@fagskolen.gjovik.no> Cc: freebsd-hackers@freebsd.org Subject: Re: A few stupid questions regarding MBR and boot0 Message-ID: <20160414155357.5990adc6@fujitsu> In-Reply-To: <alpine.BSF.2.20.1604141444310.14591@mail.fig.ol.no> References: <20160414144849.7a08b1db@fujitsu> <alpine.BSF.2.20.1604141353310.14591@mail.fig.ol.no> <20160414153627.7fc50247@fujitsu> <alpine.BSF.2.20.1604141444310.14591@mail.fig.ol.no> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Technical Discussions relating to FreeBSD <freebsd-hackers.freebsd.org> List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-hackers>, <mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe> List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers/>; List-Post: <mailto:freebsd-hackers@freebsd.org> List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help> List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-hackers>, <mailto:freebsd-hackers-request@freebsd.org?subject=subscribe> X-List-Received-Date: Thu, 14 Apr 2016 12:54:40 -0000 > Try: > > make MAKEOBJDIRPREFIX=/usr/home/eax/freebsd-obj xxx > > That should place the object tree in /usr/home/eax/freebsd-obj and > avoid polluting the source tree. > `make ... obj` works, `make ... all` fails with the same error as before. -- Best regards, Aleksander Alekseev http://eax.me/
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