Re: ioctls, etc. (was Re: [PATCH 1/4] sas: add flag for locally attached PHYs)

[Luben Tuikov]

--- Stefan Richter <stefanr@xxxxxxxxxxxxxxxxx> wrote:
> 
> Will cmd_per_lun, sg_tablesize, max_sectors, dma_boundary, 
> use_clustering ever have to be adjusted specifically for a SAS hardware?

No hardware SAS chip I know of needs any of those legacy limitations.
Neither BCM8603 nor Fusion MPT.

Those limitations are purely Parallel SCSI.

I just included it, to show proof of concept -- when the architecure and
layering is correct, how easy it is to do it.  But you're right, it is
not needed.

> Obviuosly none of this is required _at the moment_. IOW neither the 
> introduction of a sas_ha_hw_profile nor a pass-through of 
> scsi_host_template down to SAS interconnect drivers is required right 
> now. So why do one or the other now? Isn't it a sensible rule to not 
> solve problems now which do not exist yet?

This is exactly the rule I followed when developing the SAS Transport
Layer for Linux.  Furthermore, _that_ rule, to never overengineer, I learned
from Linux.  Sadly the politics are too deep and that rule applies only
to what is convenient, at least in Linux SCSI.

   Luben


-- 
http://linux.adaptec.com/sas/
http://www.adaptec.com/sas/
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