Re: Understanding LILO
moseley@hank.org writes:
> I have to ask a dumb question. When booting is lilo.conf read?
> Or is lilo.conf only used for writing the MBR plus the additional boot
> sectors? I assume it's not read while booting.
>
> I'm trying to understand the "disk", "boot", and "root" options in
> lilo.conf and when they are used (i.e. are the settings relative to the
> disk when running lilo or when booting).
>
> In the Hard Disk Upgrade HOWTO:
>
> http://www.linux.org/docs/ldp/howto/mini/Hard-Disk-Upgrade/prepare.html
>
> it shows modifying all the settings for lilo to reflect their current
> mount points.
>
> In a message yesterday from Rogier Wolff:
>
> On Tue, Jul 29, 2003 at 07:55:24AM +0200, Rogier Wolff wrote:
>
> Regarding writing the MBR on a new disk drive.
>
>> - Modify the /etc/fstab and /etc/lilo.conf files before rebooting.
>> - Add
>>
>> device=/dev/hda
>> bios=0x80
>
> I assume that was suppose to be "disk" not "device".
>
>> to Lilo.conf, mount the hda disk on /mnt and then run
>> lilo -r /mnt
>
> Ok so this make /mnt the root, so the settings in lilo.conf are relative
> to an existing setting like:
>
> install=/boot/boot-menu.b
>
> will actually install /mnt/boot/boot-menu.b
Newer LILO versions (don't apply to Debian Woody LILO) has the install= field
for compatibility purposes with older versions (<< 22.4). If you are using
Sarge or Sid, you can notice that there is not any /boot/*.b files around.
These files used to be there but it was hard to maintain them. LILO upstream
decided to put them together within the lilo binary and now the install= field
is used as a reference.
>
> But the "disk", "boot", and "root" settings will need to be changed
> before running lilo, from what I can tell.
>
> This is a bit confusing since my *new* disk is /dev/hda instead of the
> typical (see HOWTO) /dev/hdb. So I want to make sure I understand
> what's happening.
>
> My current lilo.conf settings on the RAID 1 machine have:
>
> # Overrides the default mapping between harddisk names and the BIOS'
> # harddisk order. Use with caution.
> #
> #disk=/dev/hde
> # bios=0x81
>
> #disk=/dev/sda
> # bios=0x80
>
> # Specifies the boot device. This is where Lilo installs its boot
> # block. It can be either a partition, or the raw device, in which
> # case it installs in the MBR, and will overwrite the current MBR.
> #
> boot=/dev/sda
>
> # Specifies the device that should be mounted as root. (`/')
> #
> root=/dev/sda2
>
> So, again, the *new* disk is installed in /dev/hda (my RAID is
> /dev/sda). When I'm done the disk will be installed in another machine
> also as /dev/hda.
>
> To to have lilo() install the MBR to the new disk (currently in
>
> /dev/had) I'd need to use:
>
> boot=/dev/hda
>
> (If, for example if the new drive is in /dev/hdb then I'd used
> boot=/dev/hdb).
LILO would complain if it is installed on a slave disk. (You will get a lot
of 40 at boot time). Look /usr/share/doc/lilo/Manual.txt.gz for the section
"Choosing the \"right\" boot concept" to see where and how can LILO be
installed.
>
> Now, "root" is confusing me. The HOWTO doesn't show me a "root" entry.
> I would think that root should point to where the drive will *finally*
> be installed (booted). That is,
>
> root=/dev/hda
This can only be done if you have a disk without partitions.
>
> regardless of where the disk is when running lilo. Is that correct?
> That is, if I was creating a new disk mounted /mnt that was on
> /dev/hdb I'd still use root=/dev/hda. If not correct can someone
> explain?
boot= tells lilo _where_ it will be installed
root= tells lilo what _is_ the partition where the root filesystem is
mounted.
>
> Finally, there's "disk" which looks more like a way to map hardware at
> boot time (i.e. /dev/hda is the first BIOS drive number 0x80).
>
> My current lilo.conf doesn't have a "disk" setting and I assume I don't
> need one since I'll be using a standard disk setup (first BIOS disk is
> indeed /dev/hda.
>
> So my real questions (after all that) is simply to understand the
> settings in lilo.conf and when they apply -- which is especially
> important to understand when building a drive that will end up at a
> different location than the build location.
>
> Thanks,
>
>
>
>
> --
> Bill Moseley
> moseley@hank.org
>
>
> --
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--
Andres Roldan <aroldan@fluidsignal.com>
http://people.fluidsignal.com/~aroldan
CSO, Fluidsignal Group
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