Re: HDIO_DRIVE_CMD and hdparm
From: Mark Lord
Date: Thu May 10 2007 - 09:20:43 EST
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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