Thanks Andreas, that was helpful. But I do not understand how this is harmless. If GDB does not perform exception return then I cannot follow the execution of my program by doing the command ni (next instruction) continuously.
On Thu, Mar 22, 2012 at 6:12 PM, Andreas Fritiofson <andreas.fritiof...@gmail.com> wrote: > On Thu, Mar 22, 2012 at 5:06 PM, Justin Drake <drakefjus...@gmail.com> wrote: >> I am getting the following error on the OpenOCD terminal: >> >> Error: address + size wrapped(0xfffffffe, 0x00000004) >> >> What address is referred to? What do the two addresses 0xfffffffe and >> 0x00000004 correspond to? > > In ARMv7-M, 0xfffffffX is a special value for the return address that > is placed in the link register when an exception is taken. When the > exception handler returns and the PC gets loaded with this special > value, the core knows that it should perform exception return instead > of a normal branch. This is one of the nifty features that makes it > possible to write exception handlers as regular C functions. > > However, when GDB follows the stack trace from inside an exception > handler, it ignores the fact that 0xfffffffX is a special value and > tries to load a word (0x00000004 bytes) from that address as if it was > a regular return address. OpenOCD warns that the read wraps around the > 32-bit address space, and also emits some MEM_AP errors from trying to > access these locations. Upon receiving the errors, GDB assumes it has > reached the start of the stack trace and stops. > > The error is completely harmless but could be avoided if GDB was made > aware of the special value and how to get the true return address. > > /Andreas ------------------------------------------------------------------------------ This SF email is sponsosred by: Try Windows Azure free for 90 days Click Here http://p.sf.net/sfu/sfd2d-msazure _______________________________________________ OpenOCD-devel mailing list OpenOCD-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openocd-devel
