On Thursday, August 14, 2003, at 06:53  PM, cgd@broadcom.com wrote:

> one thing that's important to note is that the CPU can't write more
> than it intends to (i.e., writing a word can't accidentally rewrite a
> whole line with an old value, as might be the case if caching on some
> HW), and neither can the device (i.e., if it's writing a word, it does
> a cycle that writes a word, rather than a cycle that writes ... more,
> possibly with out-of-date data.

Right, this is precisely the problem with wm(4) on the aforementioned 
PowerPC platform.

         -- Jason R. Thorpe <thorpej@wasabisystems.com>