Re: [RFC] generic device DMA implementation

Miles Bader (miles@lsi.nec.co.jp)
05 Dec 2002 12:17:55 +0900


David Gibson <david@gibson.dropbear.id.au> writes:
> It seems the "try to get consistent memory, but otherwise give me
> inconsistent" is only useful on machines which:
> (1) Are not fully consisent, BUT
> (2) Can get consistent memory without disabling the cache, BUT
> (3) Not very much of it, so you might run out.
>
> The point is, there has to be an advantage to using consistent memory
> if it is available AND the possibility of it not being available.
...
> Are there actually any machines with the properties described above?

As I mentioned in my previous message, one of my platforms is like that
-- PCI consistent memory must be allocated from a special pool of
memory, which is only 2 megabytes in size.

-Miles

-- 
`Life is a boundless sea of bitterness'
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