[H-GEN] USB on Linux

Christopher Biggs chris at stallion.oz.au
Sun Apr 14 22:32:15 EDT 2002


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"Frank Brand" <fbrand at uq.net.au> moved upon the face of the 'Net and spake thusly:

>
> The propensity for Linux to treat IDE, Floppy and USB etc devices as SCSI is
> archaic. 

Actually, it's not.  

It's a laudable piece of code re-use on the part of the ATAPI and USB
committees.

The USB mass-storage profile operates by sending command packets over
the USB which are in fact standard SCSI packets wrapped in the USB baggage.

ATAPI devices operate in the same fashion (using SCSI-over-ATA).

I strongly suspect that your USB-to-ATA bridge in fact presents the
usbmass interface.  So the Host OS sends SCSI commands to the bridge
device over the USB, and the bridge then sends ATA commmands to the drive.

Twisted, but sort of logical.

> I remember when the only CD Burners recognised were SCSI and that
> only some were recognised (you had to have a supported brand)...now IDE CD
> burners are recognised as SCSI. 

They *are* SCSI, but using a non-SCSI physical layer to transfer the
SCSI packets.

--cjb

-- 
 Christopher J Biggs \ chris at stallion.oz.au \ Vice-Pope Torture & Indulgences
 Stallion Technologies\ Brisbane,  Australia \   Holy Church of Givashitology
 nordfordfnrdfnodfnorfnordnordfordfnrdfnodfnorfnordnordfordfnrdfnodfnorfnordn

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