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From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Thu, 15 Sep 2016 17:41:25 +0200
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Subject: Re: TRIM/UNMAP/DISCARD via ATA Passthrough
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
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On Wed, Sep 14, 2016 at 8:37 PM, Martin K. Petersen
> How do they signal that they support the passthrough?

Through the usual SCSI ATA-passthrough interface,  "SAT"  (SCSI-ATA
Command  Translation) -- ATA PASS THROUGH SCSI (16) and ATA PASS
THROUGH SCSI (12).

I can use hdparm to treat /dev/sdb as an ATA interface:

zx2c4@thinkpad ~ $ sudo hdparm -I /dev/sdb | grep TRIM
           *    Data Set Management TRIM supported