Re: O_DIRECT alignment requirements ?
Benjamin LaHaise (bcrl@redhat.com)
Wed, 9 Apr 2003 14:08:32 -0400
On Wed, Apr 09, 2003 at 08:48:36AM -0700, Joel Becker wrote:
> In 2.5, the alignment restrictions have been relaxed. Your
> offset, buffer, and transfer size must all be aligned on the hardware
> sector size. That is the output of BLKSSZGET against the block device,
> and is also what get_hardsect_size() returns in the kernel. For almost
> all disks this number is 512b, so you can do O_DIRECT on 512b alignment
> for a raw disk or for an ext3 filesystem. About the only thing that
> may not have a 512b hardware sector size is a CD-ROM.
Well, and SCSI devices configured to use 528 byte sectors and such...
-ben
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