On 03/26/2013 07:00 PM, Chad Dupuis wrote:
On Tue, 19 Feb 2013, Hannes Reinecke wrote:
This patchset updates the SCSI midlayer to use 64-bit LUNs
internally.
It eliminates the need to limit the number of LUNs artificially to
avoid aliasing issues; the SCSI midlayer can now accept any LUN
presented
to it.
The LLDD specific settings for 'max_lun' have been left untouched;
it should be raised to '~0' if the HBA supports 64-bit LUNs
internally.
However, it is up to the driver maintainer to raise that limit.
Hannes Reinecke (4):
scsi_scan: Fixup scsilun_to_int()
scsi: use 64-bit LUNs
scsi: use 64-bit value for 'max_luns'
scsi: Remove CONFIG_SCSI_MULTI_LUN
Hannes,
As we've reviewed these patches internally, the one question that keeps
coming up is how do we handle hardware that cannot handle a 64-bit LUN
address? For example, some of our older 2G/bps hardware can only
handle a 16-bit LUN address. Currently we convert the u32 value to u16.
> Do we do the same for the 64-bit conversion? Can a way be
devised to
"opt-out" of receiving a 64-bit address in the first place (IIRC this
> was an option in the v1 patch set)?
Yes, you can.
The idea here is to let 'max_luns' control this behaviour;
'max_luns' is the highest LUN number the host can support.
So for 16-bit LUN you would set max_luns to '0xFFFF', and for 32-bit
LUN addresses you would be setting max_luns to '0xFFFFFFFF'.
However, since you mention it, maybe I should add a 'scsilun_to_u32'
conversion routine, as this is requested in several places.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
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