On Sunday 27 May 2007 23:53, John-Mark Gurney wrote:
Hans Petter Selasky wrote this message on Sun, May 27, 2007 at 22:35 +0200:
I've got some reports back that some USB host controllers do not support
transferring memory from a location higher than 2GB.
What should we do about this?
Should we limit all USB DMA allocations to the lower 2GB of the memory?
No, a quirk table should be setup and pass the restriction to bus_dma
at tag initalization time when a broken controller is detected..
Yes, I can do that. But I am also thinking about a static quirk, like a sysctl
you can set at boot time.
I hope that this is not a wide-spread problem.
And I am not surprised that hardware manufacturers are not specification
compliant, which really makes me wonder if they support a true 64-bit address
bus on the EHCI controller at all. I would maybe cost too much money? And
therefore we should just stick with 32-bit addressing on 32-bit platforms