Re: [PATCH] libata: fix broken Kconfig setup

[Linus Torvalds <torvalds@osdl.org>]

On Mon, 17 Oct 2005, Jeff Garzik wrote:
> 
> The only operational difference between CONFIG_SCSI_SATA=y and
> CONFIG_SCSI_SATA=m is that CONFIG_SCSI_SATA=m restricts the drivers from being
> compiled in -- a silly and needless restriction.
> 
> The elimination of 'y' as an option should propagate from CONFIG_SCSI.

Sure. You can do it that way too, as I mentioned in the original mail 
about why it was ugly.

But the point is:

 WHY?

Your insistence on CONFIG_SCSI_SATA being a boolean only results in uglier 
configuration, for no gain. And it's not even TRUE. It's only true if you 
consider it to be a "do we support SATA or not" thing. It's not true if 
you consider it "how do we support SATA" thing.

In other words, a tristate makes total sense, if you say that 
CONFIG_SCSI_SATA describes how SATA is supported.

> Agreed this is a _theoretical_ problem.

But it's just another sign of you thinking about that config variable the 
wrong way.

> CONFIG_SCSI_SATA is just a switch to enable listing a set of drivers, just
> like CONFIG_NET_PCI (which I note is a bool), CONFIG_NET_ISA (a bool), ...

No it's not.

CONFIG_NET_BOOL is not a tristate, because it can't be a module. There's 
nothing that forces network drivers to be modules only. Same goes for 
NET_ISA.

In contrast, CONFIG_SCSI=m _does_ force SATA drivers to be module only. 

See? They are not the same at all.

> At that point it seems easier to solve at the Kconfig level, perhaps defining
> CONFIG_SATA_INTEL_COMBINED at the end.

Sure, that makes sense.

>  And then with the quirk issue out of
> the way, CONFIG_SCSI_SATA becomes purely a boolean enable/disable-this-menu
> switch.

No it does not. You continue to ignore the fact that it's not an 
enable/disable thing. It's a "can we enable SATA drivers" vs "can we 
enable SATA drivers as modules" vs "do we do any SATA drivers at all?" 
thing.

A tristate.

Adding the SCSI config is a pure hack because you refuse to see the fact 
that CONFIG_SCSI_SATA _is_ a tristate. Thinking it is a boolean causes you 
to then have to mix in other issues.

		Linus
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