# Re: PPC64 \& DMA zone

- From: Benjamin Herrenschmidt \<benh@kernel.crashing.org\>
- Date: 2012-09-02 03:13:07 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2012/09/9470927
- Thread: https://ratatoskr.run/linuxppc-dev/2012/08/9470846/t.md

```text
On Sun, 2012-09-02 at 02:54 +0000, Tabi Timur-B04825 wrote:
> On Fri, Aug 17, 2012 at 3:40 PM, Benjamin Herrenschmidt
> [ref] wrote:
> > On Fri, 2012-08-17 at 23:04 +0300, Aaro Koskinen wrote:
> >> Hi,
> >>
> >> Is there a way to reduce/limit DMA zone with PPC64 kernel (3.6-rcX)
> >> on G5 Mac? I have tried to search Kconfig or command line options,
> >> but can't find anything.
> >
> > No.
> 
> What about Shaohui patches for ZONE_DMA?  That's meant to solve
> exactly this problem?  Granted, it sets the DMA zone to 31 bits, but
> it's simple to hack that to 30 bits.

Unnecessary for this specific problem. The right fix to the iommu code
has already been done.

Cheers,
Ben.
```