On 2018年01月24日 18:52, Christian König wrote:
Am 24.01.2018 um 11:32 schrieb Chunming Zhou:
On 2018年01月24日 17:49, Christian König wrote:
[SNIP]
Nope, as I wrote that won't work. You must improve the detection if
we need coherent or not coherent allocation.
But how to differentiate coherent or not coherent allocation? check
if max io address of system memory under 40bits pcie address space?
Do you know how to get the max io address of system memory?
Well that is a good question, which nobody had an answer for so far
(and a couple of people already looked into it).
We could start by checking if max_pfn is <= the 40bits limit or if
IOMMU is enabled instead of SWIOTLB.
How to get max_pfn?
btw, seems only amdgpu and radeon driver use dma path.
Regards,
David Zhou
Regards,
Christian.
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