Btw I wonder if the CmdQue bit should be statically set to 1 instead. It is not specified in the SAT standard (as of SAT-4 Rev. 05a) that the bit should be correlated to ATA NCQ. Neither does the kernel care about the bit (or the 'queue_type' sysfs file), apparently. However, it seems that there is still an advantage to have the bit set to 1 even when we, for example, need `libata.force=noncq` for some reason: https://github.com/YanVugenfirer/kvm-guest-drivers-windows/issues/63#issuecomment-216480833 What do you guys think? Is there any concern (with rigid reasoning) over setting the bit statically to 1? On 3 May 2016 at 04:13, <tom.ty89@xxxxxxxxx> wrote: > From: Tom Yan <tom.ty89@xxxxxxxxx> > > https://bugzilla.kernel.org/show_bug.cgi?id=105931 > > This might look trivial at first sight. However, it can be > important to have the bit set accordingly when the device/SATL is > SCSI-passthrough'd to a virtual machine with scsi-block in qemu: > > https://github.com/YanVugenfirer/kvm-guest-drivers-windows/issues/63#issuecomment-216199929 > Signed-off-by: Tom Yan <tom.ty89@xxxxxxxxx> > > diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c > index 567859c..cd30f11 100644 > --- a/drivers/ata/libata-scsi.c > +++ b/drivers/ata/libata-scsi.c > @@ -2007,7 +2007,10 @@ static unsigned int ata_scsiop_inq_std(struct ata_scsi_args *args, u8 *rbuf) > 0, > 0x5, /* claim SPC-3 version compatibility */ > 2, > - 95 - 4 > + 95 - 4, > + 0, > + 0, > + 0 > }; > > VPRINTK("ENTER\n"); > @@ -2024,6 +2027,9 @@ static unsigned int ata_scsiop_inq_std(struct ata_scsi_args *args, u8 *rbuf) > hdr[2] = 0x6; /* ZBC is defined in SPC-4 */ > } > > + if (ata_ncq_enabled(args->dev)) > + hdr[7] |= (1 << 1); > + > memcpy(rbuf, hdr, sizeof(hdr)); > memcpy(&rbuf[8], "ATA ", 8); > ata_id_string(args->id, &rbuf[16], ATA_ID_PROD, 16); > -- > 2.8.2 > -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
