Re: PATCH: usb-storage-set-last-sector-bug-flag.patch

[Greg KH <greg@xxxxxxxxx>]

On Thu, Jan 24, 2008 at 06:07:00PM +0100, Stefan Richter wrote:
> Greg KH wrote:
> > I just am worried that we are
> > now suddenly keeping access from the last sector for devices that
> > currently did work just fine.
> 
> This new workaround doesn't prevent access to the last sector.  It only
> breaks up a multi-sector access which would also reach the last sector
> into several (two? I'm too lazy to look back in the mail thread)
> accesses, in order to access the last sector in a dedicated
> single-sector access.
> 
> So that's very differently to the fix-capacity workaround.  The
> fix-capacity workaround manipulates the READ CAPACITY parameter data.
> Therefore the fix-capacity workaround is unsafe for non-buggy devices.
> 
> The last-sector-(access-)bug workaround _only_ modifies the command
> stream which is sent to the device.  A dangerous command is replaced by
> equivalent safe commands.  These commands are luckily safe for _all_
> devices, buggy and non-buggy ones.  The only cost of this workaround is
> (1.) the code, (2.) the runtime/ bandwidth/ latency overhead for
> accesses which reach the last sector.

Ok, thanks for explaining it better.  I have no objection to this change
anymore.

thanks,

greg k-h

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