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SubjectRe: Answer (Re: Cylinder limits jumper for drives over 32GB)
On Tue, 28 Mar 2000, H. Peter Anvin wrote:

> David Elliott wrote:
> >
> > Okay.. there MUST be a way to "transiently" enable the extra disk space.
> >
> > Windows 98 obviously does this. I haven't had time to play with EZ-Drive and
> > figure out how it does it... I'll see if I can look into it though.
> >
>
> Someone said it had something to do with the VV field... see other
> entires in this thread.

OOPS.........
#define VV 1 /* if set in sectorct then NOT volatile */
This is a field in the task file tansfer mode in communicating with an ATA
device........
Most FOOLS trust that if you lean on a window it will hold you inside the
building........RECALL X-Lawyer demonstrating this principle on a window
in a sky scraper........THUD!!!
The drive manufactures define it as a safe process to change the values
in the "protected memory area".........but here is the catch........
You set your system up to boot because your AWARD BIOS of 05/14/99 and
older can not handle drives larger than 32GB and you do a drive limitation
capacity thingy with an OEM application. The system now boots but your
shiny new 40GB drive is 32GB.........
You are asking Linux and ME!! to accept responsiblity for the contents of
your harddrive by issuing a "READ_MAX_ADDRESS" then perform a
"SET_MAX_ADDRESS" command to grant you access to the remaining 8GB.

First point, if I do set the "protected memory area" to retain the drive
size your system will not boot again until you run the OEM application
again!

Second point, if I do set the "protected memory area" to retain the drive
size, I have to guarentee that Linux will revert the drive capacity to a
limit below the 32GB.........
AGAIN, you expect LINUX to absorb the WRATH of FS DESTRUCTION, if for some
reason you have to boot a resque-disk that does not have this little
disk-inflator feature..........
FS CORUPTION is one thing (accidently introduced and fixed)
FS DESTRUCTION is another thing (caused by willful tinkering with a device)

Lastly, some of these drives have 1024 byte blocks and not 512 byte blocks.

******************
Solution............make the drive full size and tell your BIOS a LIE!
We discard it anyways.........and query the drive for reality.

Andre Hedrick
The Linux ATA/IDE guy



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