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SubjectRe: ATA support for 4k sector size
>>>>> "Matthew" == Matthew Wilcox <> 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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