Re: [PATCH] barrier patch set

[Bartlomiej Zolnierkiewicz]

On Saturday 20 of March 2004 03:53, Johannes Stezenbach wrote:
> Bartlomiej Zolnierkiewicz wrote:
> > On Saturday 20 of March 2004 02:48, Johannes Stezenbach wrote:
> > > hdparm -i and -I ultimately both interpret WIN_IDENTIFY result, and
> > > both test bit 0x0020 of word 85. So it's unclear to me why they report
> > > a different write cache setting. I added a hexdump to dump_identity()
> > > in hdparm.c, and found that bit 0x0020 of word 85 is always set.
> >
> > or WIN_PIDENTIFY to be strict but
> >
> > -i returns _cached_ (read when the device was probed) identify data
> > (uses HDIO_GET_IDENTIFY ioctl)
> > -I reads _current_ data directly from the device
> > (uses HDIO_DRIVE_CMD ioctl)
>
> Oh, right.
>
> But: HDIO_GET_IDENTITY returns drive->id, and surely drive->id
> is used internally. So isn't it a bug that drive->id is not
> updated when the write cache setting is changed?

No, drive->id shouldn't be changed.

> I think the barrier code uses drive->id to determine if the
> write cache is enabled.

The barrier code depends on drive->wcache.

Regards,
Bartlomiej

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