Every time I start wandering thru various writing about linux, I learn something new. This morning I did a search using the key words “how does a pc boot” (without the quotes) in the article pointed to by Bugs/grub - openSUSE I found this little gem:
In any case the Linux devices corresponding to BIOS numbers must be recorded in the file /boot/grub/device.map. You’ll see lines like
(hd0) /dev/hda
meaning Linux’ /dev/hda is what the BIOS thinks is hard disk 0, numbered 0x80 (0x00 would the first floppy drive). Make sure this mapping is correct, if you can. YAST will have generated this file using some good guessing, but you better check.
Yep. The bios creates a hardware device map in CMOS, but this is not the boot sequence. The bios uses its boot sequence to simply chain through the devices looking for the first available “boot volume” (such as a floppy) and lacking that, the first bootstrap code it can hand off to. When the boot loader gets installed, it gets help from the OS for device recognition from which some guessing can be done, but still the OS also does not know the boot sequence. Windows of course has dealt with this by arbitrarily requiring its system volume to be the active partition on the boot device; it doesn’t have the challenges grub does because it doesn’t afford such flexibility. Those who complain about grub’s difficulties in a multi-disk/mult-boot configuration, I’ll wager have never set up the equivalent with multiple Windows instances - much more difficult to do. Interestingly, Vista’s new boot loader has a number of grub’s characteristics and is designed to be flexible; regrettably it is also designed to own the entire machine, even more so than its predecessors.
the point is — The grub documentation points out that the information that linux provides is not necessarilly correct;
also that the information that the bios provides to the OS is not always what is really there; What is the point ---- do not necessarily believe what linux is telling you about the hardware.
What is the point ---- I suggest that you read the grub document I referenced.
The point is - do not believe, without confirming it, that boot/grub/device.map is necessarially accurate.
The point is providing a link to a reference that will provide anyone who cares, a place to look to find information about booting.
The grub documentation points out that the information that linux provides is not necessarilly correct . . . do not necessarily believe what linux is telling you about the hardware.
Well, not exactly. It’s not a matter of “the information that linux provides.” The grub documentation explains that grub guesses, with some assistance in the form of, to be specific, the block devices that the OS has derived from the bios map. The boot sequence is simply data that is not available; it is not written to the map. No OS can “provide” the boot sequence to the loader. All loaders, including commercial versions, depend upon the user to be configured correctly; they can make educated guesses (by looking at partition boot flags, disk signature, boot sectors), but that is all.
P.s. Also if the post was a rant it would be a soap box thingy… but, to me, it starts as a post handing out information that some might find useful. A little more description of the motivation (garyg’s) might have made this intention clearer.
On 08/06/2008 Magic31 wrote:
> Also if the post was a rant it would be a soap box thingy… but, to
> me, it starts as a post handing out information that some might find
> useful.
One man’s useful information can be another man’s waste of time. E.g. I often find a nifty trick in vi. I wouldn’t dare posting it here because most experienced Linux admins will just shrug and wonder what’s so special about it.
Uwe, you are totally out of line posting here what you did. If you want to pick a fight with me take it to the “soapbox” where it belongs.
As a moderator, you should know better!
The admins & mods have been discussing this in the moderator’s area. I think it correct to say the majority view is that most the forum sub areas (such as “install/boot/login”) were intended to be setup up as strictly a “Question and Answer” area. The scope was not intended to include technical information without a question.
Rather I believe the idea was technical information without a specific question could be handled in Soapbox, How-to, or General, where:
(a) Soapbox - I see a “soapbox” being an area where a user wishes to express an opinion that may or may not, be controversial.
(b) How-to - I see a “how-to” area being an area were a user posts guidance on how to solve a specific technical aspect.
(c) General - this is sort of catch all where helpful technical information that is not relevant to a specific question could be addressed, together with many many other non-technical aspects.
I don’t think thats a final view by any stretch … Instead that is what I perceive the “idea” to have been when the forum sub areas were setup. My view slightly differs, but I think the above is close to the majority view.
Of course we are all hoping to see improvements over time, … anyway, … if someone wishes to follow up further on this, … why not start a new thread under either “General” or under “Forums Comments/Suggestions”.
I sincerely hope my input/statement doesn’t stir things up.
Thanks for the clear and well layed out feedback oldcpu.
Personally I can live with that view, as stated earlier I would find it a shame if these forums would fall into a Q & A and soapbox kind of thing.
As the OP contains specific information about a process that falls in a category I can imagine others would end up doing the same thing. So it would be good to have a clear category for this as general seems too general?
I don’t want to reply to lengthy as I understand your (and Uwe’s) point.
We might continue discussing views and options in the suggestions part of the forum.
