Kernel never deal with physical addresses (except in ioremap function in which it takes a 32bit physical address only, so applicable for memory above 4GB) but rather it deals ins a form of Pages or pfn (page frame number) and pfn on x86 are actually equals to physical_address >> PAGE_SHIFT, and on UMA Architecture you can get the corresponding page address for physical_address through "mem_map + pfn", by the way using mem_map directly is I think not suitable. By doing this u will get the page address of the physical address and if it is mapped then that page->virtual will certainly hav the virtual address for that or just use page_to_virt function to get the virual address of tha page. If the page is of highmem then map it using kmap and kmap will resturn u the virtual address of the mapped page ......... By the way keep this in mind that I m telling this abt x86 Architecture and I don't know abt the ppc but I think that will work on that tooo ........... Thanks and Regards, Fawad --- jhoney jhoney <jhoney_joney@xxxxxxxxxxxxxx> wrote: > Date: 20 Oct 2004 15:42:58 -0000 > > Hello All, > > I am working with kernel modules , and I would like > to know the function that converts physical > processor register address to the virtual kernel > address so that that can be used in the kernel > modules for further operations. > > Thanks in Advance, > > Regards > > Jhoney --- jhoney jhoney <jhoney_joney@xxxxxxxxxxxxxx> wrote: > Subject: Problem in getting kernel vritual address > I have a board MPC 8540 ported with ppc Linux and > U-boot. U-boot is going to intialize the memory map, > like mapping 0x00000000 to SDRAM interface and > 0xe0000000 to pci interface. so when we write at > 0xe0000000 , the data will go through the pci. > Assuming that whatever the memory map done by U-boot > is carried over to the Linux, I wrote > > virtual_address = __va(0xfdf00000) to get the > virtual address for CCSRBAR , which contains > fdf00000 at offset zero.(It contains it's address at > the offset zero from the CCSRBAR). > > If I dereference the virtual_address( > *virtual_address = fdf00000) > it should contain the same address. But when i tried > this , it result in segmentation fault. pls give me > any clue. > > Above all, what I want is , the memory map is > carried from the u-boot to linux, if so how to get > the virtual address(to manipulate in the kernel > module) for the physical address to manipulate the > processor registers. > > Thanks in Advance > > Regards > > Jhoney > _______________________________ Do you Yahoo!? Declare Yourself - Register online to vote today! http://vote.yahoo.com -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
