Messages in this thread | | | Date | Sat, 20 Mar 2004 02:48:37 +0100 | From | Johannes Stezenbach <> | Subject | Re: [PATCH] barrier patch set |
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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).
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.
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?
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