RE: [t13] 48-bit LBA: Purpose of ID Word 86, bit 10 (vs ID 83, bi t 10)

[Mark Overby]

Title: Message

I agree with Michael. The bits should be in lock step - this is what our driver expects as well. We don't do test runs either. (Inefficient for boot time)   -----Original Message----- From: Eschmann, Michael K [mailto:[EMAIL PROTECTED] Sent: Wednesday, February 04, 2004 1:11 PM To: ATA T13 Reflector Subject: RE: [t13] 48-bit LBA: Purpose of ID Word 86, bit 10 (vs ID 83, bit 10)   Steve, why in the world would one bit be off and the other on?  There's no enable/disable control for this feature, so these bits must correlate with each other.   If you allow bit mis-correlation in your drives, I can guarantee you that most drivers will not operate 48-bit commands and the user doesn't get what he payed for.   Jeff, I test both bits in word 83 and 86, plus verify that the capacity words are greater than 128GB before I enable 48-bit commands in my driver.  I don't believe that drivers test-run a command during disk enumeration...I know I don't.   Drivers make a choice based on the identify data flags and start sending commands, then clean-up if they fail during run-time.   MKE.     -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Stegmier, Steve Sent: Wednesday, February 04, 2004 10:03 AM To: ATA T13 Reflector Subject: RE: [t13] 48-bit LBA: Purpose of ID Word 86, bit 10 (vs ID 83, bit 10)   -----Original Message----- From: Wolford, Jeff [mailto:[EMAIL PROTECTED] Sent: Tuesday, February 03, 2004 7:36 PM To: ATA T13 Reflector Subject: [t13] 48-bit LBA: Purpose of ID Word 86, bit 10 (vs ID 83, bit 10) ID Page Word 83, bit 10 indicates support for 48-bit LBA addressing[Stegmier, Steve] s/b Command sets supported  ID Page Word 86, bit 10 indicates support for 48-bit LBA addressing[Stegmier, Steve] s/b Command set/feature enabled    Q1: Which is it ?[Stegmier, Steve]  Word 83 bit 10 indicates that the device supports the feature (the feature may be enabled or disabled).  Word 86 bit 10 indicates the feature is enabled.   Q2: Are both required to be the same value ?[Stegmier, Steve] The bits may be different.    Q2.1: If not the same, does one have priority over the other ?[Stegmier, Steve] If Word 83 bit 10 is off I would not expect to ever see Word 86 bit 10 on. When Word 83 bit 10 is on, Word 86 bit 10 may be off or on.   Q3: Does software have to check both bits or is checking Word 83 (and being set)[Stegmier, Steve] Checking Word 86 bit 10 is sufficient. valid.   Thanks,   Jeff   Jeff Wolford                       Email: [EMAIL PROTECTED] Master Architect Storage Interface and Tools - Business PC Group     Voice: (281) 514-9465,     Pager: (800) 973-5739 Hewlett-Packard Corporation