I've been reading the UIO code, one place puzzled me a lot.
May I ask one question about it?
-------------------------------------------------------------------------------
drivers/uio/uio.c
static int uio_find_mem_index(struct vm_area_struct *vma)
{
int mi;
struct uio_device *idev = vma->vm_private_data;
for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
if (idev->info->mem[mi].size == 0)
return -1;
if (vma->vm_pgoff == mi)
return mi;
}
return -1;
}
I don't get it why use vma->vm_pgoff as the index for struct uio_mem mem[MAX_UIO_MAPS],
Suppose there are twohardware memory space, if user intends to map the 2nd mem, then
the last parameter of mmap should be 1,
mapaddr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED,
fd, 1);
Is my understanding correct?
thanks
bill
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