2.6 kernel

[Gene C.]

On Tuesday 16 December 2003 14:36, Alan Cox wrote:
> On Tue, Dec 16, 2003 at 01:28:09PM -0500, Gene C. wrote:
> > To me it seemed to matter since it was not using the LBA values but the
> > "actual" (real) values of the device.
>
> Real ? which real 8)
>
> With old disks doing C/H/S its all fairly easy, because there is a real
> geometry. Once you get drives too big for CHS (about 528Mb if I remember
> rightly) then you switch to LBA, LBA28, LBA48. In those modes its more like
> scsi, what you are really talking about is block offset from zero. The
> entire CHS concept is so much irrelevance wiht modern drives that its not
> too big an issue how you chop it up. You also have to allow for the fun
> corner cases
>
> 	-	Drive strapped to report below real size to bios
> 		(and possibly partitioned otherwise)
> 	-	Partition table and other offsets in cylinders
>
> Thats where it gets really nasty. If the partition table laid down by
> windows says x sectors per track and we use a different geometry then all
> track based calculations between Linux and Windows will disagree. End
> result-> not pretty.

Yes, I have had a "not pretty" situation arise for me in the past and it is 
very not pretty.

OK, I ran "a test" on a dual P-II (400MHz, 386MB) and /dev/hda is a WDC 
AC36400L drive.

I first installed FC1 with / as hda1 and swap on hda2.  rebooted a couple of 
times and this works OK.

I then tried installing fc-development (from last night) into hda3 .. it is 
only 6.4GB so that fills the drive.  grub boot is installed in the MBR

First time I specified nothing.  I got the popup which mentioned the BIOS 
conflict 784,255,63 versus 13328,15,63.  I switched to VT-2 and ran fdisk.  
This showed LBA like values of 784,255,63.

I then rebooted and tried installing again but with linux hda=784,255,63 ... 
BTW NFS installs.

This time it came up, I switched to VT-2 again and manually allocated hda3 
with fdisk.  I then proceeded with the install.  grub is installed in the 
hda3 partition.

After installation, reboot into FC1 (hda1) and modify /boot/grub/grub.conf to 
add:
   rootnoverify (hd0,2)
   chainloader +1

Reboot into fc-dev (hda3).  Boots up fine.

Under both systems when I run fdisk /dev/hda the disk geometry is reported as 
784,255,63.

The is another drive on the system (currently empty).  This is an 18GB WDC.

Under FC1, fdisk reports the goemetry as 2193,255,63.

Under FC-dev, fdisk reports the geometry as 34960,16,63.

On this system where I did not worry about screwing things up, that is the 
result.

I have not (and do not plan to) do anything with my current other test system 
where I have Win2k installed in hda1.  That would be looking for trouble and 
Win2k take far too long to install to want to repeat it.
-- 
Gene