Date: Mon, 20 Nov 2000 18:03:27 +0800 From: John Summerfield <summer@OS2.ami.com.au> To: freebsd-stable@freebsd.org Subject: Re: Dedicated disks (was: Dangerously Dedicated) Message-ID: <200011201003.eAKA3RS01865@possum.os2.ami.com.au> In-Reply-To: Message from Greg Lehey <grog@lemis.com> of "Mon, 20 Nov 2000 19:20:44 %2B1030." <20001120192044.Q58333@echunga.lemis.com>
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grog@lemis.com said: > On Sunday, 19 November 2000 at 23:57:25 -0800, David O'Brien wrote: > On Mon, Nov 20, 2000 at 02:53:04PM +1030, Greg Lehey wrote: >> >> If > it shows valid partitions, you're using a Microsoft partition table. > ^^^^^^^^^^^^^^^^^^^^^ > Greg, can you read English?? Can you comprehend it?? Are you bind > and in > a write-only mode?? > For the last time IT IS NOT A MICROSOFT PARTITION TABLE but a PC BIOS > PARTITION TABLE AND DICTATED BY THE INTEL x86 PLATFORM. THEY ARE ALSO > REQUIRED BY THE IA-64 PLATFORM. > > Why do you *insist* on calling it a "Microsoft partition table"?? > Hmm. I was going to say "Because it was introduced with Microsoft > 2.0", but I'm no longer so sure. Reading the MS-DOS 2.11 source code, > it seems that they didn't have a partition table at the time. Can > anybody remember when it was introduced? Nothing to do with the PC BIOS: 1. The PC did not support fixed disks (introduced with the XT). The PC understood floppy disks and cassette tape. 2. The BIOS has enough intelligence to read the first sector from a disk and then jmp into it. This sector is called the Master Boot Record, and it contains the original partition table and code with enough intelligence to find the active partition, read a teensy bit of it (using BIOS calls) and pass control to the code read in this manner. If you want a dedicated BSD disk, you replace this code with equivalent code to find where BSD lives. Or Solaris. In the original implementation of these partitions, one could have no more than four. Of these, only one could be active and so PCDOS/MSDOS didn't need code to navigate much partition table. As to who concocted it, it was Microsoft and/or IBM. What uses this format natively? All the DOS family down to Windows 2000|ME and OS/2. And Linux. And the CP/M family. There is some dissension wrt extended partitions - MS keeps on introducing new codes for partition types. Here are the partition types Linux fdisk recognises: [root@emu /root]# fdisk Using /dev/hda as default device! Command (m for help): l 0 Empty c Win95 FAT32 (LB 64 Novell Netware a6 OpenBSD 1 DOS 12-bit FAT e Win95 FAT16 (LB 65 Novell Netware a7 NEXTSTEP 2 XENIX root f Win95 Extended 75 PC/IX b7 BSDI fs 3 XENIX usr 11 Hidden DOS FAT1 80 Old MINIX b8 BSDI swap 4 DOS 16-bit <32M 14 Hidden DOS FAT1 81 Linux/MINIX c7 Syrinx 5 Extended 16 Hidden DOS FAT1 82 Linux swap db CP/M 6 DOS 16-bit >=32 17 Hidden OS/2 HPF 83 Linux native e1 DOS access 7 OS/2 HPFS 40 Venix 80286 85 Linux extended e3 DOS R/O 8 AIX 41 PPC PReP Boot 93 Amoeba eb BeOS fs 9 AIX bootable 51 Novell? 94 Amoeba BBT f2 DOS secondary a OS/2 Boot Manag 52 Microport a5 BSD/386 ff BBT b Win95 FAT32 63 GNU HURD Command (m for help): How many are used natively, and how many under sufferance, I do not know. Note: this table is not completely accurate: the OS/2 definition of 0x07 is "installable filesystem." It's usually HPFS, but need not be. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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