[OpenBIOS] [PATCH] Fix up LANCE ethernet DMA mapping under Solaris 8 on SPARC32.
Mark Cave-Ayland
mark.cave-ayland at siriusit.co.uk
Mon Apr 25 21:05:43 CEST 2011
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
PostgreSQL - PostGIS
Sirius Corporation plc - control through freedom
http://www.siriusit.co.uk
t: +44 870 608 0063
Sirius Labs: http://www.siriusit.co.uk/labs
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