On Tue, Jun 12, 2018 at 10:28:26AM -0500, Bruce Dubbs wrote: > On 06/12/2018 12:43 AM, Michael Shell wrote:
> > There are a lot of things that can go wrong when disk sector numbers are > embedded into the code like lilo does. I do not know anything about the > internals of elilo though. > (Just a few comments, not related to EFI) - I liked lilo, and I deviated from the book to use it on most of my machines - perhaps only one had grub-legacy at that time, and that was just for testing the book. Hell, on pure64 (cross-lfs) we couldn't even build grub-legacy at first. And then /dev/hda became /dev/sda - I never managed to get lilo to work with /dev/sd if the machine was currently booting from /dev/hd. > > > BTW, IIRC, anyone using a BIOS-based initial load, either grub, lilo, > > etc., must ensure that the (second stage) boot loader as well as any > > kernel image files are located within the first 2 TB of the drive > > because the BIOS calls can't handle sector numbers beyond that. > > I don't think you can say that for all BIOS firmware, but it is certainly > true for some. Personally, I always make the grub partition sda1. > My only machine with drives bigger than 2TB uses them for RAID-1 not for booting. ISTR that I had to use GPT on them to be able to use the whole drive. For msdos partitioning, I've got /boot all over the place - sda14 on one machine which is towards the end of a nominally 500GB drive. > > > I believe the slots the sata drives are plugged into have priorities. > > > I've never seen the disks reverse identification. that would really be > > > a bad race condition. If it was happening, we would certainly have > > > heard about it. > > > > I can't remember exactly how I was bitten by it, but it wasn't via USB. > > It might have been from the use of a removable rack or SD card to SATA > > adapter (as a "rescue" boot) that sometimes would have media in it and > > sometimes not. > > On my oldest machine (very old) the drive devices move around according to which connectors have a drive attached. I think I've also seen that on other machines over the years : plug in only to the first connector, it is sda, but add another drive on a "later" connector and sda became sdc. Not all connectors on some consumer-grade motherboards use the same SATA driver. > > In any case, according to > > https://wiki.archlinux.org/index.php/persistent_block_device_naming > > > > "If your machine has more than one SATA, SCSI or IDE disk controller, the > > order in which their corresponding device nodes are added is arbitrary." > > Yes. I recall using e2label for consistent naming (I think on that machine, even with the exact same connections, a newer kernel could also move them around - and that is, of course, with the drivers built-in. > > As I understand it, that is the policy of the kernel developers - a system > > might work in many cases, but it is not guaranteed and a future kernel > > update could break systems that rely on any fixed /dev/sd* naming. To me, > > this means that, until udev becomes active and we can control things as we > > wish, any /dev/sd* specifiers are to be considered worthless. > > I see. I guess I've never had a system with multiple disk controllers. My > development system has six sata drives, but they are all plugged into the > motherboard so that is one controller. I think that multiple controllers > are rare outside of large organizations. > > > I do not like that policy. Unless countermanded by a kernel option, > > on-motherboard controllers should be enumerated before those of any add-on > > card or USB device. > > USB is separate as is a CD/DVD device. At least it is in any BIOS that I > have worked with. Perhaps it is a problem if multiple USB drives are > plugged in at boot. I have not tried that. Plugging in a usb drive before power on often used to give problems. ĸen -- Keyboard not found, Press F1 to continue -- http://lists.linuxfromscratch.org/listinfo/lfs-support FAQ: http://www.linuxfromscratch.org/blfs/faq.html Unsubscribe: See the above information page Do not top post on this list. A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail? http://en.wikipedia.org/wiki/Posting_style
