Messages in this thread | | | Subject | Re: dma coherent memory user-space maps | From | Thomas Hellström (VMware) <> | Date | Mon, 21 Oct 2019 14:26:38 +0200 |
| |
On 10/8/19 2:34 PM, Thomas Hellström (VMware) wrote: > Hi, Christoph, > > Following our previous discussion I wonder if something along the > lines of the following could work / be acceptible > > typedef unsigned long dma_pfn_t /* Opaque pfn type. Arch dependent. > This could if needed be a struct with a pointer and an offset */ > > /* Similar to vmf_insert_mixed() */ > vm_fault_t dma_vmf_insert_mixed(struct device *dev, > struct vm_area_struct *vma, > unsigned long addr, > dma_pfn_t dpfn, > unsigned long attrs); > > /* Similar to vmf_insert_pfn_pmd() */ > vm_fault_t dma_vmf_insert_pfn_pmd(struct device *dev, > struct vm_area_struct *vma, > unsigned long addr, > dma_pfn_t dpfn, > unsigned long attrs); > > /* Like vmap, but takes struct dma_pfns. */ > extern void *dma_vmap(struct device *dev, > dma_pfn_t dpfns[], > unsigned int count, unsigned long flags, > unsigned long attrs); > > /* Obtain struct dma_pfn pointers from a dma coherent allocation */ > int dma_get_dpfns(struct device *dev, void *cpu_addr, dma_addr_t > dma_addr, > pgoff_t offset, pgoff_t num, dma_pfn_t dpfns[]); > > I figure, for most if not all architectures we could use an ordinary > pfn as dma_pfn_t, but the dma layer would still have control over how > those pfns are obtained and how they are used in the kernel's mapping > APIs. > > If so, I could start looking at this, time permitting, for the cases > where the pfn can be obtained from the kernel address or from > arch_dma_coherent_to_pfn(), and also the needed work to have a > tailored vmap_pfn(). > > Thanks, > /Thomas > > Ping?
Thanks,
Thomas
| |