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SubjectRe: [PATCH] barrier patch set
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?

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

Johannes
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