-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Fri, May 11, 2007 at 03:39:08PM -0400, Michael Cashwell wrote: > I'm trying to make sense of an Oops in a driver I'm trying to port > from 2.4 to 2.6.21 on an embedded ARM platform. I've scoured every > archive and Google page I could find but because my issue is very > specific I can't find anything that helps. > > In a nutshell, I have the module building and loading for 2.6 but > when a user land app attempts to use the driver it fails (unable to > handle kernel paging request). > > The address in question is of the CPU's internal peripheral > registers. The key issue is that I can access that address from > kernel mode just fine. But the failure happens when the user land app > down-calls via an ioctl into the driver module. The oops message says > it was "Mode SVC_32 Segment user". > > I thought I'd read that once the syscall happens and the driver is > called by do_ioctl (which is happening) that it should be in kernel > mode. I don't understand what else I need to do to allow me to access > kernel mappings that I know exist. It *is* running in kernel mode, and that's also what the Oops says: SVC_32 is ARM supervisor mode (aka kernel mode). It also says that the problem is accessing user mode memory. Without having seen the source, I guess you're probably directly dereferencing a userland address without using copy_from_user(). > Is there a call I need to make to reach kernel mode? Or am I supposed > to map the physical range I need again during an init down-call? I don't understand what you mean, sorry. Have a look at the mmap() details in LDD3 (google for ldd3 and it will take you to the right place). Erik - -- They're all fools. Don't worry. Darwin may be slow, but he'll eventually get them. -- Matthew Lammers in alt.sysadmin.recovery -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD4DBQFGRX+F/PlVHJtIto0RAuppAJQILN5Q8LFSpU1uqFQWgSv2AFLcAJ9uHUzJ j1AoQl2OS1017BnkSCofLw== =B9AT -----END PGP SIGNATURE----- -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
