Messages in this thread | | | From | Bartlomiej Zolnierkiewicz <> | Subject | Re: [PATCH] barrier patch set | Date | Sat, 20 Mar 2004 03:13:05 +0100 |
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On Saturday 20 of March 2004 02:48, Johannes Stezenbach wrote: > Bartlomiej Zolnierkiewicz wrote: > > On Saturday 20 of March 2004 00:01, Matthias Andree wrote: > > > BTW, speaking of identify-device, hdparm -i (which uses > > > HDIO_GET_IDENTITY) always returns "WriteCache=enabled" while hdparm -I > > > that uses HDIO_DRIVE_CMD with WIN_PIDENTIFY reports the "correct" state > > > that I've previously set with -W0. This is an i386 machine w/ > > > 2.6.5-rc1. > > > > > > Is HDIO_GET_IDENTITY working correctly? > > > > There were reports that on some drives you can't disable write cache > > and even (?) that some drives lie (WC still enabled but marked as > > disabled).
Doh, I misunderstood the question.
Correct answer is: everything is fine, RTFM (man hdparm). ;-)
> 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)
> BTW, 'cat /proc/ide/hda/identify' or 'hdparm -Istdin > </dev/ide/hda/identify' reports the same value as hdparm -I, and that is > consistent with > the value I set with hdparm -W x. > > > So, is HDIO_GET_IDENTITY broken?
No.
Regards, Bartlomiej
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