Re: [PATCH] aic79xx should be able to ignore HostRAID enabled adapters

Jeff Garzik
2005-12-01T17:49:46Z

Salyzyn, Mark wrote:
> Justin Gibbs had provided the community the emd driver, soundly rejected
> and never ported to dm because there were features that Justin held dear
> in md that do not translate to dm. An unfortunate waste of considerable
> resources.

All throughout development, before Justin had written a single line of
code, he was told to do things via Device Mapper. All he had to do was
open his ears, and no resource waste would have occurred.

> Without the timely agenda and cooled temperaments to close the gap, the
> solution should be temporarily to support the proprietary HostRAID
> driver when the Adapter is in HostRAID mode and we continue to work to
> close that gap on dmraid.
[...]
> They are plain SCSI HBAs, but are designated as a RAID card rather than
> a Host Bus Adapter in the PCI config space when in 'HostRAID' mode. The
> fact that is designated in the PCI space should be enough reason *not*
> to attach a simplified LLD.

Strongly disagree.

Linux should export the [non-RAID] hardware capabilities, nothing more.

We don't shim for not-in-tree binary-only drivers. A user continues to
be free to simply -not use- aic79xx, regardless of this design decision.
SATA controllers come with all sorts of class codes: RAID (host/fake
raid), SCSI (fake RAID/fake scsi), IDE, Serial ATA.

We ignore that, and just export the hardware. The class code is only a
hint that dmraid should be loaded on top of the low-level driver.

> Linux is not about performance first, it is about doing it the Linux
> way. I believe we can understand that. And in turn, do not consider it
> harmful if a group of individuals trying to make a living see a chance
> to acquire a competitive edge.

We don't do it "the Linux way" just for NIH's sake. There are strong
reasons why we want cross-vendor solutions. There are strong reasons
why we don't want every driver to embed a software RAID engine inside
it. And there are strong reasons (some legal, not technical) why its
best to ignore binary-only, out-of-tree drivers.

Jeff