Re: QESTION For Real Kernel Hackers. ATA IDENTIFY DATA & NT/2K

> Yes, this occur only for > 8GB drives.

But, your not answer to my question-
Why UserAddressableSectors field always= 0x70000?(on any IDE drive
with LBA mode)
on NT4/2K?
When i booting UserAddressableSectors = true value(after BIOS, before
NT/2K start)…
May be NT/2K change this value?

Dunno. Is it updateable at all?
BTW - NT4 completely ignores any BIOS settings for the drive. It will work
with the drive (and support DMA on it) even if nothing is set in the BIOS
for it.
Not so with w2k - it relies on BIOS to set the PIO/DMA modes for a drive,
though ignores the BIOS geometry.
If you have the drive not in BIOS and w2k - then w2k will refuse to use UDMA
on the drive, and will work in slow PIO mode.
Since the OS has no abilities of querying any BIOS/CMOS data for the drive -
then the ATA IDENTIFY DATA is the only place by means of which this can be
passed from BIOS to w2k’s ATAPI.SYS.
Something like - BIOS sends some commands to the drive, after which the
drive changes the IDENTIFY DATA and reports the UDMA support to the w2k’s
ATAPI driver.

Max


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> Satish wrote:

>
> U wanted actual size of HDD, I mean in ur case u should get 15GB right ?

Yes!

> how are u reading the size to detrmine the HDD size ?

driver.c
=== cut here ===

Are you replacing the system-supplied ATA driver? If no - then why not query
the system’s ATA driver for the disk IDENTIFY data?

Max


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