Will update you on how it goes .
Generally the only reason for me to do it , is to check how does the
SATA drive acts when it receives two identical tags.
(Erroneous scenario).

Is there a simple way to assure that the user space application is the
only one which writes to this disk ?
The disk is a seperate drive , not the System one , and generally the
user space is the only one touching it.
Nothing is installed on it.
Which other process in the system might touch it ?

Will use your help.
Thanks

On Fri, May 22, 2009 at 2:53 AM, Gwendal Grignou [off-list ref] wrote:

On Wed, May 20, 2009 at 2:20 PM, Dan Porat [off-list ref] wrote:

quoted

Thank plenty for your answer.

So , what is the best way to send NCQ through user space ?
Is it possible to disable the tagging mechanism by the driver and only
rely on the tag given by the user space ?

That's one solution, but that's quite risky, it can be difficult to
guarantee nobody else access the disk. Another one is to alter
ata_scsi_pass_thru() to use qc->tag in case of FPDMA command. It is
already calculated before we enter the translation function.
Let me know how it goes,

Gwendal.

quoted

Thanks


On Wed, May 20, 2009 at 10:53 PM, Gwendal Grignou [off-list ref] wrote:

quoted

Hi Dan,

tf->nsect can not be calculated from user space: the tag must be
calculated by the driver.

Gwendal.

On Tue, May 19, 2009 at 11:11 AM, Dan Porat [off-list ref] wrote:

quoted

As I have seen sg_io does not support NCQ in ATA passthrough.
will changing the mapping function libata-scsi.c (line 2745) , work?

If not , how else can I check the protocol (FPDMA) ?
static u8
2725ata_scsi_map_proto(u8 byte1)
2726{
2727        switch((byte1 & 0x1e) >> 1) {
2728        case 3:         /* Non-data */
2729                return ATA_PROT_NODATA;
2730
2731        case 6:         /* DMA */
2732        case 10:        /* UDMA Data-in */
2733        case 11:        /* UDMA Data-Out */
2734                return ATA_PROT_DMA;
2735
2736        case 4:         /* PIO Data-in */
2737        case 5:         /* PIO Data-out */
2738                return ATA_PROT_PIO;
2739
2745        case 12:        /* FPDMA */
                      return ATA_PROT_NCQ
2740        case 0:         /* Hard Reset */
2741        case 1:         /* SRST */
2742        case 8:         /* Device Diagnostic */
2743        case 9:         /* Device Reset */
2744        case 7:         /* DMA Queued */

2746        case 15:        /* Return Response Info */
2747        default:        /* Reserved */
2748                break;
2749        }
2750
2751        return ATA_PROT_UNKNOWN;
2752}



Thanks

Dan Porat
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