On Fri, 2013-06-07 at 07:58 +0000, Zang Roy-R61911 wrote: > > > -----Original Message----- > > From: Benjamin Herrenschmidt [mailto:b...@kernel.crashing.org] > > > > Hi Folks ! > > > > Is there any specific reason why you chose 1T (40 bit) as the location of > > the 64-bit DMA window ? > > > > It happens that most current radeon adapters cannot DMA there, they have > > a 40-bit DMA limit. I seem to be getting things to work fine using a 39- > > bit window, but I suppose that might collide with something else ? > T4240 has 40bit physical address ability. > " > This chip's 40-bit, physical address map consists of local space and external > address > space. For the local address map, 32 local access windows (LAWs) define > mapping > within the local 40-bit (1 TB) address space. Inbound and outbound > translation windows > can map the chip into a larger system address space such as the RapidIO or > PCIe 64-bit > address environment. This functionality is included in the address > translation and > mapping units (ATMUs). > > " > That should be the reason to set the DMA window to 40-bit.
I see. However if the top half of that space isn't used by default with whatever is our current setup, it makes sense to move down the 64-bit DMA window to allow those adapters to function don't you think ? I'm trying to turn those FSL boxes into nice ppc64 dev. workstations :-) Cheers, Ben. > > > > Can you guys consider changing the default ? > Any collide for 40bit? > Roy _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
