同时有些是用到其他资源，jvm也不会进行回收，类似Io流中的FileInputStream使用到了硬盘资源，垃圾回收器...
然后,dma_mmap_coherent函数调用remap_pfn_range函数,将物理地址映射到用户空间的虚拟地址空间中。remap_pfn_range函数的原型如下: ```c int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, unsigned long pfn, unsigned long size, pgprot_t prot) ``` 该函数将指定的虚拟地址范围(addr到...
3.映射设置:然后,函数通过调用remap_pfn_range函数将这段物理内存映射到用户空间的虚拟地址空间。这个函数需要传入虚拟内存区域结构体vma,以及物理页帧号、映射大小和映射权限等信息。 4.返回值设置:最后,函数将CPU可访问的内存地址和DMA地址分别赋值给参数cpu_addr和dma_handle,然后返回0表示成功。 四、dma_mmap_co...
正如我在问题的更新中发布的那样，潜在的问题是，零复制网络不适用于已使用映射的内存remap_pfn_range()...
I then tried allocating the memory using kmalloc (instead of dma_alloc_coherent), and use remap_pfn_range again for mmap. Everything works fine this time. I believe because it is cacheable memory, the driver-write data is correctly read by application. Can...
I then tried allocating the memory using kmalloc (instead of dma_alloc_coherent), and use remap_pfn_range again for mmap. Everything works fine this time. I believe because it is cacheable memory, the driver-write data is correctly read by application. Can...
Next, dma_mmap_coherent maps the physical memory to the user space using the remap_pfn_range function. This functionestablishes a mapping between a range of the process's virtual address space and the physical memory addresses. It takes care of setting up the necessary page table entries and ...