Date: Mon, 14 Dec 1998 10:02:16 -0500 From: Bob Flavin <ribo@watson.ibm.com> To: freebsd-questions@FreeBSD.ORG Subject: Boot process and how disk partitions are named Message-ID: <3.0.6.32.19981214100216.02269d40@ribox.watson.ibm.com>
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I need documentation on the boot process, specifically, how BIOS/FreeBSD assign devices names to SCSI disks (from 3 SCSI channels on 2 SCSI adapters) and which one gets booted and where the kernel is loaded from and what is the order of execution of code through running the /etc/rc files. I couldn't find where stuff like how the mapping of SCSI adapters and devices and FDISK partitions to /dev/sd0s1a or /dev/sd2 or /dev/sd2s1 etc gets done. I assumed that sd1 would refer to the second SCSI controller (even though it has two SCSI channels on it). Would sd1s2 refer to the second hard disk on the second SCSI adapter? Does sd1s2b refer to the second FDISK partition (meaning also the second filesystem) on that second controller and second disk? Given all that, what is the algorithm and process used to boot? BIOS seems to start booting from the designated disk on the LAST SCSI controller found (in this case a PCI card rather than the first SCSI, which is on the motherboard). FreeBSD seems to call this disk something like sd2. But when FreeBSD (probably the boot manager) gets control, it seems to boot the operating system off sd0. Does that boot manager look for the 'boot' flag in FDISK? Bob To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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