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Re: Permissions denied when enabling DMA



On Sun, Aug 03, 2003 at 12:05:18AM +0200, Wayne Gemmell wrote:
> > Using hdparm to force DMA is a bad, bad, BAD idea.  The kernel usually has
> > very good reasons for not enabling it.
> Do you mean that I shouldn't use hdparm at all? I have a laptop that is set by 
> default with DMA and 32bit mode set off, is it also BAD to enable these on 
> the laptop because I am able to. How do I make this a default on boot?

No, I said using hdparm to force DMA is a bad idea.  I didn't say anything
about the other things hdparm can do.

Further, if the kernel you're running defaults to DMA off, then obviously
you'd either recompile the kernel or use hdparm.

The idea is to know *why* DMA didn't get enabled, not blindly start
stomping on settings.  As someone else pointed out in this thread, did it
not get enabled because there's no support for it, or because there is
support and it's not enabled by default, or because the particular
drive/controller combination is blacklisted, etc.

But for most people, it's usually easier to just stomp first and whine
later when the data goes away, I must admit.  Don't be that person. :)

-- 
 Marc Wilson |     Resisting temptation is easier when you think you'll
 msw@cox.net |     probably get another chance later on.



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