> -----Original Message----- > From: Benjamin Herrenschmidt [mailto:[email protected]] > > On Fri, 2013-06-07 at 07:58 +0000, Zang Roy-R61911 wrote: > > > > > -----Original Message----- > > > From: Benjamin Herrenschmidt [mailto:[email protected]] > > > > > > 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.
> > 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 ... thanks. Roy _______________________________________________ Linuxppc-dev mailing list [email protected] https://lists.ozlabs.org/listinfo/linuxppc-dev
