Use of Pre-fetch Command

Pat LaVarre p.lavarre at IEEE.org
Thu May 20 17:56:12 PDT 2004


* From the T10 Reflector (t10 at t10.org), posted by:
* Pat LaVarre <p.lavarre at ieee.org>
*
> > Does anyone know of an OS, application, driver, or any other host
> > software that uses the SCSI pre-fetch command?
> ...
> specifically ...
> the 0x34 (10 byte) and
> 0x90 (16 byte) opcodes.

Yes.

Does anyone?

Hello all you firmware folk who implemented this op for the sake of what
actual host?

> > Does anyone know

If we write a proposal to obsolete the op, its users might then appear
here ...

> > Does anyone know of an OS, application, driver, or any other host
> > software that uses the SCSI pre-fetch command?
> ...
> specifically ...
> the 0x34 (10 byte) and
> 0x90 (16 byte) opcodes.

The following exercise yields the name include/scsi/scsi.h PRE_FETCH for
the op x34.  Not a very fruitful search, sorry.  I was much curious,
thank you.

Other seemingly fruitless searches include:

http://groups.google.com/groups?q=PRE_FETCH+0x34
http://www.google.com/search?q=PRE_FETCH+0x34

I think this is enough homework to justify asking linux-scsi.

Pat LaVarre

----- cat 'http://lxr.linux.no/search?v=2.6.5&string=define.*0x28' |
grep -i read

...
include/linux/cdrom.h -- #define GPCMD_READ_10 0x28
include/scsi/scsi.h -- #define READ_10 0x28
drivers/block/cciss_cmd.h -- #define CCISS_READ 0x28 // Read(10)
drivers/block/paride/pf.c -- #define ATAPI_READ_10 0x28
drivers/scsi/pci2000.h -- #define SCSIOP_READ 0x28
drivers/cdrom/sbpcd.h -- #define CMD2_READ 0x28
drivers/ide/ide-floppy.c -- #define IDEFLOPPY_READ10_CMD 0x28
...

----- cat 'http://lxr.linux.no/search?v=2.6.5&string=define.*0x34' |
grep -i fetch

include/scsi/scsi.h -- #define PRE_FETCH 0x34

----- cat 'http://lxr.linux.no/search?v=2.6.5&string=define.*0x90' |
grep -i fetch

[no hits]

----- http://lxr.linux.no/search?v=2.6.5&string=PRE_FETCH

[only one hit, the defining hit, no referring hits]
[i.e. a pointless (but individually negligible) waste of compile time]

include/scsi/scsi.h -- #define PRE_FETCH 0x34

-----


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