Grub Manual

[Karl Larsen]

Lamar Owen wrote:
> On Friday 19 October 2007, Jacques B. wrote:
>   
>> As for Karl's knowledge/expertise and accomplishments in other areas,
>> I don't doubt it.  It has never been discussed because it is
>> ultimately not relevant.  
>>     
>
> Had I not done a little digging into Karl's area of expertise, I would find 
> him quite annoying to the extreme (and I did, in fact, for some time).  Now 
> that I know where he's coming from, I only find it slightly annoying.  I find 
> the backlash against him far more annoying than I find him.
>
>   
>> Because that does not automatically make him 
>> knowledgeable or an expert in the topics he is discussing on this
>> list. 
>>     
>
> Of course.
>
> But what I found is that I don't think he considers himself an expert at all 
> (correct me if I'm wrong, Karl); he's just trying to help in the way in which 
> he's used to helping.
>
> I am no expert auto mechanic either; however, I found a trick in removing and 
> installing the power steering lines on a 1987 Ford Taurus that I bet is not 
> in any of the manuals; should experienced auto mechanics automatically 
> dismiss my attempts at describing a serious timesaver just because I don't 
> use the 'correct' terminology?  (I did this myself; I didn't have a 
> particular factory tool to remove one of the things the manual said I had to 
> remove; it took me twelve hours to get the first line off without removing 
> the hard-to-remove part, but fifteen minutes later I had the second line off, 
> and both new lines on once I found the trick.  A dealer mechanic told me I 
> was crazy, that there was no way.  I told him that I'd be glad to show him 
> how I did it; he ridiculed the description of my method and said that it 
> could not possibly work; so I went down and demonstrated to the assembled 
> technicians at the dealership; jaws dropped when I did both lines in thirty 
> minutes, and me not a mechanic....)
>
> Being an expert does not automatically make somebody right; not being an 
> expert doesn't make someone wrong, either, even if the terminology 
> isn't 'correct.'  Correctness only counts if it is for communicating the 
> concept; correctness just for correctness' sake is simply pedantic.
>   
    Thank you all for coming to my defense in a thoughtful way. Indeed I 
am in no way an expert at Grub. But I am a quick learner even at 72 
years old. I have digested what you all have said and applied it to the 
small file I wrote on the Grub Manual. So rather than write what I have 
learned I will simply put the paper here for you to read again.

    Please no more about what is root. I do feel it is well covered now. 
By the way the old version was right too. I think this might be more clear.

                      GRUB MANUAL PART 1

    There is nothing simple about what Grub does. It is the tiny 
software that let us boot our Linux or Windows operating systems. At 
first look at what it takes in the file /grub/grub.conf to boot a Linux 
system.

Figure 1:
title Fedora (2.6.22.1-41.fc7)
        root (hd0,5)
        kernel /boot/vmlinuz-2.6.22.1-41.fc7 ro root=LABEL=f7 rhgb quiet
        initrd /boot/initrd-2.6.22.1-41.fc7.img

    Figure 1 is a typical grub.conf entry from an actual working system. 
Root is used twice in this entry and so first what is meant by root? The 
root directory is the directory from which all other directories come 
from in a file system.

    Many people keep the entire Linux in one partition and in that case 
both of the root point to the same partition. Others like to use more 
partitions and there is a root directory for each of them and the root 
calls point to different partitions.

    It is 4 lines and each are required and they need to be perfect. 
Below is taken from the above but actual things are replaced by numbers 
so we can talk to each.

Figure 2:
title 1
        root (2)
        kernel 3,4
        initrd 5,6

    The title can be anything you want. Your computer often wants to use 
the name of the kernel.

    The root(2) written in grub form is the partition  where the grub 
directory and kernel and initrd files are found. A typical one will look 
like root(hd0,3) which says a partition on the first hard drive and the 
4th partition.

    Kernel 3 tells grub where the files are in the root(2) partition. 

    Kernel 4 is the root= which is the partition where the kernel will 
find the system. The partition is shown in normal terms like /dev/sda5.

    For example look at this working grub.conf entry:

Figure 3:
title Fedora (2.6.22.9-91.fc7)
        root (hd0,5)
        kernel /vmlinuz-2.6.22.9-91.fc7 ro root=/dev/sda5  quiet
        initrd /initrd-2.6.22.9-91.fc7.img

 From our work above we are not interested in the title but we want to 
figure out what the root is. It says hd0,5 which means in words hard 
drive 1, partition 6 which can be also written /dev/sda6.

    Notice kernel and initrd and see they are just written as, for 
example kernel /vmlinuz... This means the two files are in the root 
directory of /dev/sda6.

    The kernel line has root=/dev/sda5 which means the system to be boot 
is in the /dev/sda5 partition even though the grub and kernel files are 
in the /dev/sda6 partition.

    So this example is one in which the boot and system partitions are 
different. They can be on different hard drives too.






-- 

	Karl F. Larsen, AKA K5DI
	Linux User
	#450462   http://counter.li.org.