HEADS UP: major CAM ATA MFC

[Alexander Motin]

Jeremy Chadwick wrote:
> On Thu, Nov 19, 2009 at 10:22:53AM +0200, Alexander Motin wrote:
>> Read ahci(4) carefully. It has all possible references. If you think it
>> is not enough, propose patches.
> 
> I had no idea said details were in the ahci(4) man page, and I doubt the
> rest of the user community will know that either.  There's also no man
> page for ada(4).
> 
> There is some ambiguity in this part of the ahci(4) man page:
> 
>   AHCI hardware is also supported by ataahci driver from ata(4) subsystem.
>   If both drivers are loaded at the same time, this one will be given
>   precedence as the more functional of the two.
> 
> The grammar here is very difficult to understand; "if both drivers" is
> too vague.  The way this paragraph can be interpreted:
> 
> - "If both drivers" could refer to ata(4) and ataahci

No. ataahci is a part of ata(4).

> - "If both drivers" could refer to ata(4) and ahci(4)

Yes, if with ata(4) understand it's ataahci part.

> - "If both drivers" could refer to ada(4) and ahci(4)

No. It is mentioned in ahci(4), that ada is peripheral driver. Not a
controller.

> - "If both drivers" could refer to ahci(4) and ata(4)

It is same as second.

> I'll happily re-write the documentation for this if someone can take the
> time to explain what the paragraph actually is trying to say. 

Welcome.

> Users are
> going to be very, very confused if there is a driver called ataahci and
> another driver called ahci.

This is temporal situation, until new infrastructure will settle. Then
old one will be removed.

> Finally, appropriate details need to be placed into the i386 and amd64
> kernel configuration files; either in GENERIC (commented out) or in
> /sys/conf/NOTES.  As it stands, there's nothing that informs anyone of
> this change, and if users are being pointed to the ahci(4) man page,
> they're going to get confused (see above).

Both new ahci and siis drivers are mentioned in NOTES file.

-- 
Alexander Motin