On Fri, 2013-06-07 at 09:44 +0000, Zang Roy-R61911 wrote: > > > -----Original Message----- > > From: Benjamin Herrenschmidt [mailto:b...@kernel.crashing.org] > > > > 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 ? > Good to me. > 40 bit DMA will prevent your radeon video card from working. Right? > Your P5020 DS system only support 36 bit physical address.
We should probably put the "64-bit DMA" address in the device-tree, that way if somebody wish to do differently they can. > > > > I'm trying to turn those FSL boxes into nice ppc64 dev. workstations :-) > That is good. I'd like to see how long it will build a kernel ... I'll tell you when you send me a 24 cores e6500 :-) In the meantime I'll build them on my 16-cores (64 threads) P7+ :-) I'm more thinking about how to seed general community developers with machines they can use to ensure things work fine on ppc64 without having to get them a rack in their basement... Cheers, Ben. > thanks. > Roy _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
