Re: Kernel Summit request for Discussion of future of ATA (libata) and IDE

["Bartlomiej Zolnierkiewicz" <bzolnier@gmail.com>]

I'm using gmail's interface (I don't have access to my laptop ATM) so
the mail may look a bit weird...

On Sun, Aug 3, 2008 at 5:57 PM, James Bottomley
<James.Bottomley@hansenpartnership.com> wrote:
> Right at the moment, we have two separate subsystems for running IDE
> type devices:  driver/ide and drivers/ata.  The claim I've seen is that
> drivers/ata can do everything drivers/ide can do plus it does sata.  I

This claim doesn't seem to have confirmation in facts:

* There is still hardware that is simply not-supported by libata at all:

  - architecture specific hardware (ppc, m68k, mips, arm)

  - "difficult" legacy PC-class hardware (i.e. secondary interface on
CY82C693 etc)

* There are still regressions in many libata PCI host drivers dating back
  to their rushed introduction.

* There are still corner case in libata core - PIO is dead slow
compared to drivers/ide/,
  "serialized" hosts are not supported, some quirks for obsolete
hardware got lost...

> also note that no major distribution seems to enable anything in
> drivers/ide anymore, so given this is it time to deprecate drivers/ide?

Major distributions make their own decisions (I don't remeber anybody from
these distros discussing the conversion on linux-kernel or linux-ide) which
sometimes don't match with what kernel.org kernels are doing.

[ Actually one distro went so far as CONFIG_IDE=n even before support for
  all PC-class IDE PCI hardware present in drivers/ide was available
in libata. ]

Also the same major distros that use libata on x86 are using
drivers/ide on non-x86.

> A counter argument to the above is that not all drivers (particularly
> the older ones where hw is scarce) are converted to drivers/ata, so
> drivers/ide seems to be needed for some legacy systems (in which case it
> can be deprecated but not removed).  I've also noted that some embedded
> distributions seem to be using drivers/ide, but I'm not really sure
> whether this is inertia or some overriding need.

drivers/ide deprecation would be a premature thing.

> The proposal is to discuss the future of these two subsystems and arrive
> at a consensus what's happening to each going forwards.

Well, I'm looking forward to discuss the future of Linux ATA support.

Thanks,
Bart