如果我只有设备缓冲区（PCIe）接口的物理地址，我怎么可以映射此缓冲用户空间？ [英] If I have only the physical address of device buffer (PCIe), how can I map this buffer to user-space?

问题描述

如果我只有内存缓冲区的物理地址以被映射通过PCI-Ex的preSS BAR设备缓冲区（基址寄存器），我怎么可以映射此缓冲区以用户空间

If I have only the physical address of the memory buffer to which is mapped the device buffer via the PCI-Express BAR (Base Address Register), how can I map this buffer to user-space?

例如，如何通常code应该看起来像Linux的内核？

For example, how does usually the code should look like in Linux-kernel?

unsigned long long phys_addr = ...; // get device phys addr
unsigned long long size_buff = ...l // get device size buff

// ... mmap(), remap_pfn_range(), Or what should I do now?

在的Linux x86_64的

从：<一href=\"http://stackoverflow.com/a/17278263/1558037\">http://stackoverflow.com/a/17278263/1558037

的ioremap（）物理地址映射到内核虚拟地址。
   remap_pfn_range（）物理地址直接映射到用户空间。

ioremap() maps a physical address into a kernel virtual address. remap_pfn_range() maps physical addresses directly to user space.

来源： http://stackoverflow.com/a/9075865/1558037

int remap_pfn_range(struct vm_area_struct *vma, unsigned long virt_addr, 
    unsigned long pfn, unsigned long size, pgprot_t prot);

remap_pfn_range - 重映射内核内存用户空间

remap_pfn_range - remap kernel memory to userspace

可能是我可以用它呢？

unsigned long long phys_addr = ...; // get device phys addr
unsigned long long size_buff = ...l // get device size buff

remap_pfn_range(vma, vma->vm_start, (phys_addr >> PAGE_SHIFT), 
    size_buff, vma->vm_page_prot);

问：但是，我在哪里可以得到 WMA ，以及我必须pre-DO与 WMA 调用 remap_pfn_range（）之前？

Question: But, where can I get wma, and what I must pre-do with wma before call to remap_pfn_range()?

推荐答案

Linux内核，至少，版本2.6.x的使用的ioremap（）功能。

The Linux kernel, at least, versions 2.6.x use the ioremap() function.

void *vaddr = ioremap (phys_addr, size_addr);
if (vaddr) {
  /* do stuff with the memory using vaddr pointer */
  iounmap (vaddr);
}

您应该做一个previous调用 request_mem_region（）来检查，如果内存空间已经被其他司机回收，并礼貌地要求内存被国有您code（驱动器）。完整的例子应该是这样的：

You should make a previous call to request_mem_region() to check if that memory space is already reclaimed by another driver, and politely request that memory to be owned by your code (driver). The complete example should look like this:

void *vaddr;
if (request_mem_region (phys_addr, size_addr, "my_driver")) {
  vaddr = ioremap (phys_addr, size_addr);
  if (vaddr) {
    /* do stuff with the memory */
    iounmap (vaddr);
  }
  release_mem_region (phys_addr, size_addr);
}

您可以通过检查的/ proc / iomem中检查你的所有权，这将反映在地址范围，并在你的系统中的每一块内存的所有者。

You can check your ownership by checking /proc/iomem, which will reflect the address range and the owner of every piece of memory in your system.

更新：我真的不知道，如果这个工程的64位内核。它为32位。如果64位内核没有这些内核函数，他们将有类似的，我想。

UPDATE: I don't really know if this works for 64-bit kernels. It does for 32-bit. If 64-bit kernel don't have these kernel functions, they will have similar ones, I guess.

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