Messages in this thread | | | Date | Tue, 14 Sep 2004 17:25:09 +0200 | From | Jens Axboe <> | Subject | Re: Changes to ide-probe.c in 2.6.9-rc2 causing improper detection |
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On Tue, Sep 14 2004, Jeff Garzik wrote: > Alan Cox wrote: > >On Maw, 2004-09-14 at 07:06, Jens Axboe wrote: > > > >>Alan, I bet there are a lot of these. Maybe we should consider letting > >>the user manually flag support for FLUSH_CACHE, at least it is in their > >>hands then. > > > > > >You are assuming the drive supports "FLUSH_CACHE" just because it > >doesn't error it. Thats a good way to have accidents. > > > >The patch I posted originally did turn wcache off for barrier if no > >flush cache support was present but had a small bug so that bit got > >dropped. > > > FWIW the libata test for checking whether it is OK to issue a flush is > > return ata_id_wcache_enabled(dev) || > ata_id_has_flush(dev) || > ata_id_has_flush_ext(dev); > > and if it passes that test, > > if ((tf->flags & ATA_TFLAG_LBA48) && > (ata_id_has_flush_ext(qc->dev))) > tf->command = ATA_CMD_FLUSH_EXT; > else > tf->command = ATA_CMD_FLUSH; > > I wouldn't object to removing the "ata_id_wcache_enabled" test if people > feel that it is unsafe.
Alan says it's unsafe for some of his flash cards, and I do believe they say they have write caching enabled.
-- Jens Axboe
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