Re: HDIO_DRIVE_CMD and hdparm

[Mark Lord <lkml@rtr.ca>]

Geert Uytterhoeven wrote:
> 	Hi,
>
> `hdparm -t' uses HDIO_DRIVE_CMD(null) to flush the disk's buffer.

More correctly, that command is supposed to act like an I/O queue "barrier"
operation, not returning from the syscall until everything queued in front
of it has been issued/completed.

I believe that only the original IDE driver actually implements it, though.
And hdparm-7.4 (not released yet) will no longer complain about ENOTTY.

Note that current versions of hdparm use SG_IO/ATA_16 (SAT) for nearly everything
now, only falling back to the older ioctl's for drivers which reject the SAT attempt.

I'd love to find a USB drive enclosure that supports SAT.
Anyone know of one?

And does the USB storage layer actually pass the ATA_16 packets to the device?

Cheers
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