On Tue, May 24, 2005 at 09:19:28PM +0200, Niklaus Giger wrote: > Hi > > I am working on a custom PPC405 board where I have a 2.6.10 kernel with RTAI > patches (fusion) running. > > I am trying to access some custom CPLD chip hanging at 0x7D000000. In my > intial board (hcu3_map_io) I added a corresponding io_block_mapping.
Is a "corresponding" mapping a 1:1 mapping? Don't do that. You cannot map stuff that way since it is below TASK_SIZE i.e. it's in user address space, not kernel address space. > Now I compiled a module which tries to access the CPLD during the insmod phase > and I get the following output. > > Oops: kernel access of bad area, sig: 11 [#1] <snip> > What is wrong with my code? You mapped the device into user virtual address space. The TLB replacement code is unable to load a TLB entry for a page outside of kernel space...so you crash. Don't use io_block_map()...it allows you to shoot yourself in the foot very easily (as you just witnessed). Use ioremap() to map your device. -Matt
