lkml.org 
[lkml]   [2008]   [May]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: MMIO and gcc re-ordering issue
Trent Piepho wrote:
> Is there an issue with anything _besides_ coherent DMA?
>
> Could one have a special version of the accessors for drivers that
> want to assume they are strictly ordered vs coherent DMA memory?
> That would be much easier to get right, without slowing _everything_
> down.

It's better to be safe by default and then optimize the fast paths than
to be relaxed by default and hang the machine in some piece of code that
runs once a month. "Premature optimization is the root of all evil",
and what not.

> One could even go as far as to allow a driver to "#define
> WANT_STRICT_IO" and then it would get the strict versions. Add that
> to any driver that uses DMA and then worry about vetting those
> drivers.

See above -- if you must have a #define, then it should be WANT_RELAXED_IO.

-Scott



\
 
 \ /
  Last update: 2008-05-27 20:35    [from the cache]
©2003-2011 Jasper Spaans