Subject: Re: Large Disks / Clean Install
To: None <>
From: Wolfgang Solfrank <>
List: current-users
Date: 02/08/1999 14:35:48

> Hum, well, yes, if the BIOS is happy with the MBR, that is.  Some
> BIOSes aren't happy with our current /usr/mdec/mbr, see PR 6954,
> i.e. it refuses to run the code, apparently because some consistency
> check done by the BIOS on the MBR fails.

Actually (see my other mail to you on that PR) this is quite likely not
a problem of the BIOS not approving the MBR code, but of os-bs not being
able to make our MBR code bootable from the second disk.  To the best
of my knowledge there is _no_ MBR code that can be booted from the second
disk as is.  (This is certainly true for any version of M$'s code I've
looked at).

> Also, it appears that M$'s mbr code isn't the same in all cases; I got
> the distinct impression from the description of the aforementioned /x
> switch to fdisk that at least some newer variants of fdisk's MBR code
> does know how to do int13 extensions (?).  Of course my old MS-DOS
> fdisk didn't recognize that switch.  No, I've not tried to disassemble
> the M$ mbr code as installed by Windows95, so I may be wrong on this
> one.

Yes, there are different versions of M$'s code installed with and without
int13-extension support.  Ever seen the question fdisk asks whether you
want large disk support enabled?  That's what makes the difference.

And, the int13 extension support in M$'s code is quite limited.  It will
only use these extensions for certain partition types, so you cannot boot
a non-FAT partition beyond the 8GB-limit using it.

ws@TooLs.DE     (Wolfgang Solfrank, TooLs GmbH) 	+49-228-985800