On Thu, Nov 09, 2006 at 12:57:29AM +0100, Marcel Kilgus wrote: > Daniel Jacobowitz wrote: > >> Leaving that aside, if I do set the breakpoint correctly at virtual > >> address (e.g.) 0xC0123456 qemu will (correctly I guess) cause an > >> exception for code offset 0x123456 (as CS base is 0xC0000000). GDB > >> however then doesn't recognize its own breakpoint as it only remembers > >> having set one at 0xC0123456, and apparently doesn't translate the > >> given exception address of CS:0x123456 back to a virtual one. > > Which segment is it running from at this point? Qemu may be reporting > > the wrong address. > > After paging is switched on, all code always runs in the CS that is > based at 0xC0000000. As I see it qemu reports the address just fine. > As I wrote in my original mail it only works if I set two breakpoints, > one at 0x123456 and one at 0xC0123456. Makes sense then, the > 0xC0123456 triggers the breakpoint exception within qemu and the > 0x123456 is used by GDB to recognize the offset it gets from qemu. > It's a mess, really, and probably not qemu's fault.
If qemu is ever sending "0x123456" back to GDB in the scenario you've described, you can probably get the right behavior by simulating flat memory: make qemu add the segment base to the pc when it sends it to gdb. At this point you're past what I know about i386 though. -- Daniel Jacobowitz CodeSourcery _______________________________________________ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
