svn commit: r200171 - in head: sbin/atacontrol sys/arm/mv sys/cam/ata sys/cam/scsi sys/conf sys/dev/ata sys/dev/ata/chipsets sys/powerpc/powermac sys/powerpc/psim

[Roman Divacky]

On Sun, Dec 06, 2009 at 12:10:13AM +0000, Alexander Motin wrote:
> Author: mav
> Date: Sun Dec  6 00:10:13 2009
> New Revision: 200171
> URL: http://svn.freebsd.org/changeset/base/200171
> 
> Log:
>   MFp4:
>   Introduce ATA_CAM kernel option, turning ata(4) controller drivers into
>   cam(4) interface modules. When enabled, this options deprecates all ata(4)
>   peripheral drivers (ad, acd, ...) and interfaces and allows cam(4) drivers
>   (ada, cd, ...) and interfaces to be natively used instead.
>   
>   As side effect of this, ata(4) mode setting code was completely rewritten
>   to make controller API more strict and permit above change. While doing
>   this, SATA revision was separated from PATA mode. It allows DMA-incapable
>   SATA devices to operate and makes hw.ata.atapi_dma tunable work again.
>   
>   Also allow ata(4) controller drivers (except some specific or broken ones)
>   to handle larger data transfers. Previous constraint of 64K was artificial
>   and is not really required by PCI ATA BM specification or hardware.

are there any performance benefits of the 64K limit removal?