>>>>> "Christoph" == Christoph Lameter <clameter@xxxxxxx> writes: Christoph> There is code in Andrews tree that allows getting rid of Christoph> ZONE_DMA. I know that SGI machines do not use ZONE_DMA. I Christoph> looked through the arch code and I do not see ZONE_DMA or Christoph> GFP_DMA uses that I cannot account for. However, I am not Christoph> familiar with the code for other IA64 platforms. Christoph> This patch will make IA64 have a single zone in each Christoph> node. As a result loops are unrolled, various VM macros can Christoph> be optimized further and the memory load balancing code Christoph> between different zones in one node is no longer Christoph> necessary. Note that having no ZONE_DMA means that GFP_DMA Christoph> will be ignored. If you know of any devices depending on Christoph> ZONE_DMA (memory returned must be below 4GB) then we first Christoph> need to deal with those possibly by modifying Christoph> dma_alloc_coherent functions to obtain memory in a Christoph> different way than via GFP_DMA. If you want to take this path, are you then planning to move the < 4GB memory into ZONE_DMA32? We need a way to allocate memory within the 4GB zone for 32 bit DMA devices, especially on systems without an IOMMU. In fact, it's attractive to be able to get memory in the 4GB zone when possible even if a device supports DAC as it reduces the number of bus transactions since it can be done with a single address cycle instead of a dual. Jes - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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