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

[Mark Cave-Ayland]

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.


ATB,

Mark.

-- 
Mark Cave-Ayland - Senior Technical Architect
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