Dear Andrew Lunn, On Thu, 21 Mar 2013 21:37:51 +0100, Andrew Lunn wrote:
> > And I'm not sure the SDRAM address decoding windows allows to split the > > first 4 GB of RAM into two areas, one that would be mapped starting at > > physical address 0x0, and another area that would be mapped at a > > different address (above 4 GB). > > So why not map the whole SDRAM above 4GB physical address? As Lior rightly pointed out to me, this would prevent any device from DMA-ing to or from the RAM. Devices can only access the first 32 bits of the physical address space. So there must be some RAM below 4 GB. Best regards, Thomas -- Thomas Petazzoni, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
