Messages in this thread | | | Subject | Re: ATA support for 4k sector size | From | "Martin K. Petersen" <> | Date | Thu, 26 Feb 2009 00:16:00 -0500 |
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>>>>> "Matthew" == Matthew Wilcox <matthew@wil.cx> writes:
Matthew> Lowest aligned logical block address=0
Matthew> This disagrees with Martin's assertion.
Quick answer from one of my contacts. Desktop drives will indeed ship with an alignment of 1(*). The alignment is hardwired at time of manufacture and can't be changed.
(*) I had to go back and reread the ATA spec to grok this. READ CAPACITY(16) indicates the lowest naturally aligned LBA. With LBA 63 offset in play that would be LBA 7.
ATA, on the other hand, indicates how much LBA 0 is offset from the beginning of the first physical sector. If LBA 63 is naturally aligned that means that LBA 0 is offset 512 bytes (physical sector 0 starts at LBA -1 if you will). Hence IDENTIFY DEVICE word 209 will contain 0x4001.
So you need to tweak your RC16 response a bit...
-- Martin K. Petersen Oracle Linux Engineering
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