1. YDL 1.2 Synergy VGM5 Virtual Address, Physical Address, Bus Address and remap_page_range (HELP!)
I am currently developing a kernel module to communicate with a PCI memory
device and I have run into a few problems.
1. How do I determine the physical address of my PCI device? I did examine
the IO-mapping.txt file in /usr/scr/linux and it states the following is
true for Power PC:
Physical Address: 0x0
Virtual Memory Address: 0xC0000000
Bus Address 0x80000000
Using lspci -v I find that the bus address of my device is as follows:
memory at 0xF0042100 non-prefectable
memory at 0xF1000000 prefetchable
memory at 0xF2000000 prefetchable
So how do I figure out the physical address for the bus address 0XF1000000
do I just subtract/add 0x80000000 to get the address?
2. I need the physical address because I am trying to obtain it to pass into
remap_page_range() (I need to map all of the memory from my PCI device into
kernel memory and then pass a pointer from the kernel to user space. I tried
using the value of 0x71000000 (which I obtained by subtracting 0x80000000
from 0xF1000000 and it doesn't work:
User mode application:
if( (fd = open( SCR_INT_DEV, O_RDWR )) == -1 )
rvalue = DEVICE_ERROR;
paddr = mmap( 0, 0x80000, prot, mmap_flags, fd, 0 );
if( (int)paddr == -1 )
rvalue = MAP_ERROR;
(mmap entry point in kernel module)
static int pci_mmap(struct file * file, struct vm_area_struct * vma)
physical += vma->vm_offset;
mapped_mem = vma->vm_end - vma->vm_start;
if (remap_page_range(vma->vm_start, 0x71000000, mapped_mem,
This works fine on a Linux 2.2.18 distribution running on an X86 (I
understand that on the Power PC that Phy addr and bus addr aren't the same)
I realize that this is a non-portable way of accessing memory, but our API
requires that it receive a user pointer to directly access memory from our
card. Can anyone please help me or point me to information that might help
me to solve the problem.
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