moving linux installs

[Thomas Charron]

On 4/21/08, Ben Scott <dragonhawk at gmail.com> wrote:
>  Windows NT (2000/XP/...) work a lot more like GRUB.  The NTLDR file
> is kind of like GRUB's stage2.  I'm not sure how the MBR boot block
> gets around to loading it.

  The MBR block loads based on an offset from the start of the
partition, loading NTLDR.  The NTLDR code is actually part of the file
system itself, it's existence is actually stored in two locations, one
before the actual file system, with a symbolic entry in the file
system itself.  This is why some defragmenting programs can spooge
NTLDR.  It's not JUST a file, it's actually in a fixed location
beforte the actual file allocation tables.

> But NTLDR uses the BIOS for I/O, reads
> BOOT.INI for config, and then loads several dozen different files to
> get NT running.  That includes reading the registry for information on
> which drivers to load.  Gulp.

  Correct, The MBR snippet loads NTLDR, and NTLDR reads a sparse file
table which points to the special $Boot 'file'.  I guess in reality,
NTLDR is actually stage1.5 thinking about it.

>  Right, but since Windows is all plug-and-play and everything,
> doesn't that mean all we're really accomplishing is avoiding a bunch
> of yellow-bang icons in Device Manager (for the hardware that suddenly
> disappeared)?  I mean, yah, sure, it makes things cleaner, but it's
> not exactly critical.  No?

  Kinda.  It also serves as a way to say 'when in this profile, ignore
this device'.  A laptop, for instance, may ignore the built in
ethernet NIC when docked into a docking station that also has a NIC.

> > AFAIK, Linux (-based distros) doesn't offer such a facility.
>  Well, that depends on what you're looking for.  There's no "Hardware
> Profiles" GUI dialog box thingy (and $DEITY willing, there never will
> be).  But if you attempt to load modules for all the hardware you
> *might* have, the kernel will only keep the ones for hardware it
> actually finds.  So if your NIC might be a 3Com or might be an Intel,

  However, in my case it's much more difficult to boot my Linux
partition natively, and under VMWare without a significant amount of
'meddling'.  For instance, dynamic reconfiguration of X.org, alsa
configurations, NetworkManager, etc..  Profiles specifically address
those issues, to the point where the registry is swapped in and out
depending on which profile you're loading.  Not a 'super' concept,
it's simular to renaming /etc back and forth.  :-D

> >  I haven't counted, but does Linux support more than a hundred-ish types of
> > disk controllers these days?  If not, I'd rather see them all available all
> > the time ...

  You can.  Build them all as modules, and have initramfs include all
of them.  Your initial ramdisk would be pretty hefty, but it would
work.  I believe many install disks do something simular.

-- 
-- Thomas