Why not just name the cam-ata devices the same as the old names?

[Alexander Motin]

Hi.

Doug Barton wrote:
> I'm not nearly as smart as you are, so please explain to me like I'm
> dense. :)  Why can we not simply give the devices created by ata-cam the
> same names they have under the old ata system?

Don't underestimate yourself, or don't make me blush. ;)

There are two problems: names and unit numbers.

We can't use same names because old and new stacks coexisting last 18
months (and they will forever in 8.x), and it was possible to just load
single ahci module of new stack for SATA devices, while PATA were
working via old stack. Using same name would cause collisions. Now when
we are going to switch to the new stack completely, coexistence could be
a bit less important, but there is already number of migrated systems
and they would suffer from the second renaming.

Even if we do something with names, there is a problem with device unit
numbers. Previous numbering scheme of ATA_STATIC_ID reserved only two
device numbers per ATA channel. It was working fine for PATA times, but
it is not now. When SATA port multipliers are used (and it is not so
rare now), there could be up to 15 devices per channel, plus multiplier
itself. They just won't fit.

-- 
Alexander Motin