Pavel Roskin writes:
>
> Also it seems that the mapping is only activated when
> chainloader is used and it has no effect on GRUB itself. Should
^^^^^^^^^^^ ^^^^^^^^^
> it be fixed or documented?
>
IMO, this is a feature, not a bug. This is what the map command
is for.
Of course the map command has no effect on grub itself - grub has
to first read the chainloader into memory, then just before the
chainloader is given control, the map command is performed. From
then on the BIOS calls that the chainloader makes will then use
the mapped values.
Consider a chainloader like lilo or the DOS partition boot block.
These chainloaders are early binding - they think that they know
they have been installed on hd0 (DOS), or they reference some disk
sector on hd1 (lilo), etc.
So, how to make these chainloaders work, if for example, hd0 is
physically un-installed, but I want to boot from a partition on
what was previously hd1 - which is now hd0.
I use the map command - when lilo asks the BIOS to read sector n
from hd1 - the sector will actually be read from hd0.
You can make grub use late binding - this is what the `d' flag is
for. So if you want to use a grub that has been installed with
the `d' flag after you physically changed the drive number - you
just boot your emergency grub boot floppy, use the map command,
then chainload to boot the grub with the now out of date late
binding.
HTH,
--
Jeff Sheinberg <[EMAIL PROTECTED]>
