Re: 2 PATCHES: fix request_tranferlength

Kurt Garloff
2002-07-22T01:24:12Z

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Hi Matt,

On Sun, Jul 21, 2002 at 05:05:23PM -0700, Matthew Dharm wrote:
> We're asking for an odd number of bytes in the command... this just affects
> the tranfer length field. It doesn't actually change the command sent.
>
> Also, this is the sd.c driver -- SCSI disks. OnStream _tape_ drives are
> unaffected by this change. :)

Sure. But Willem's remark is valid.

There has been a firmware bug in some old FW for OnStream tapes that made
them go nuts when inquired an odd length on a wide connection.
It's been fixed since long, but it may not be the only one.

According to Gérard, you can even expect error messages on a wide bus when
requesting odd numbers of bytes. Though I never agreed with his reasoning.
(IMHO: You should get an ignore wide residual message on reads; on writes you
need to send one extra byte which the device should ignore. Neither of which
I consider an error condition. Nor a situation where you have a residual.)

Regards,
--
Kurt Garloff <kurt@garloff.de> [Eindhoven, NL]
Physics: Plasma simulations <K.Garloff@TUE.NL> [TU Eindhoven, NL]
Linux: SCSI, Security <garloff@suse.de> [SuSE Nuernberg, DE]
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