Question about ioremap and io_remap_page_range

From: 舒国强 (
Date: Thu Sep 27 2001 - 01:04:42 EST

 Here is some rather basic questions I want ask ,any reply or comment please
 CC to my emailbox,thank you very much.
 When I work with kernel 2.4.2 in Intel X86 , I use
     VIRT_ADDR = ioremap(BUS_ADDR); to map a section of PCI memory, and
     X_ADDR = virt_to_phys(VIRT_ADDR);

  I think in x86 platform X_ADDR should equel with BUS_ADDR, but it turns to be
 NOT, can you explain ?

  In X86 platform ,Can I use return value of ioremap() as a memory pointer?

  I use io_remap_page_range(BUS_ADDR,,) in mmap() function,but the result is
 that the memory I map is READ ONLY from user space,when I try to write to it,
 a "do_sw_pg. bogus page(XXXXXXXX)" appears. Can you explain to me?

  I know these questions are childish,but I need the answer urgently,thanks!

 George Shu


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