Re: Re: BUG in kernel: Wrong Handling of USB HDDâsin scsiglue(slave_configure) and scsi/sd(sd_read_cache_type)

From: Alan Stern
Date: Mon Oct 03 2011 - 15:54:07 EST

On Mon, 3 Oct 2011, James Bottomley wrote:

> On Mon, 2011-10-03 at 14:10 -0400, Alan Stern wrote:
> > > No. You need to also take into account the RBC
> > > device parameters mode page if present. See above.
> >
> > All right, suppose neither page is present. Does it then make sense to
> > assume by default that write caching is enabled?
> You're the USB expert ... if we do that, we'll start sending
> SYNCHRONIZE_CACHE commands down to a whole slew of devices we didn't
> before ... is that going to cause problems with any USB SATLs?

Hmmm... Actually, I doubt it would bother any SATLs, but it might well
bother other sorts of USB translation layers. No way to tell without
trying it, and I don't really want to deal with the fallout.

Maybe a better question to be asking is this: What happens when one of
these drives (the ones that report their caching capabilities
incorrectly) is plugged into a Windows system?

Alan Stern

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