DMA

[Lee Revell]

On Tue, 2006-05-23 at 18:49 +0100, Sean Hammond wrote:
> On 5/23/06, Scott James Remnant <scott at ubuntu.com> wrote:
> > On Tue, 2006-05-23 at 15:34 +0100, Sean Hammond wrote:
> >
> > > I often find that DMA is disabled by default on machines running
> > > Ubuntu, and that in order to (for example) play DVDs smoothly I have
> > > to enable it following these instructions:
> > >
> > > https://wiki.ubuntu.com/DMA
> > >
> > If DMA is disabled by default, then you're running the risk of crashing
> > or damaging your machine by enabling it.
> 
> So I've heard. Does this mean that Windows enables DMA by default on
> many such systems and runs the risk, whereas Ubuntu/Debian/(Linux?)
> are more cautious?
> 

("Enable DMA" is ambiguous - many devices like sound cards always use
DMA and it cannot be disabled.  This thread is about DMA for
IDE/ATAPI/SATA devices)

Windows does not enable DMA for disk drives on every system either.

If there are really many systems where the kernel does not enable DMA
for the disk controllers by default, but it is safe to do so, it should
be reported to the kernel people. 

Lee