[OpenBIOS] [PATCH] Fix up LANCE ethernet DMA mapping under Solaris 8 on SPARC32.

Blue Swirl blauwirbel at gmail.com
Mon Apr 25 22:51:17 CEST 2011


On Mon, Apr 25, 2011 at 10:05 PM, Mark Cave-Ayland
<mark.cave-ayland at siriusit.co.uk> wrote:
> On 25/04/11 19:11, Blue Swirl wrote:
>
>> Would it make any difference if IOMMU region were 16M so that the base
>> would start at 0xff000000?
>>
>> Otherwise the patch looks OK.
>
> Maybe, but there are still difficulties with that. For example, ESP claims
> its IOMMU memory first, so I was seeing that ESP would get 0xfe000000 while
> LANCE would get 0xfe001000 - so even changing the base is no guarantee this
> will work. And of course, as soon as the kernel takes over the IOMMU page
> table then the existing mappings disappear - unless there is some weird
> kernel logic that only preserves mappings above a certain limit such as
> 0xff000000?
>
> So in short, given the amount of effort involved for a similar result I
> don't see many advantages over the fixed address mapping implemented in the
> patch.

It's fine then. It's just good to know that this is a bit of a hack.



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