Hi Will, > > - It seems odd that the kernel says it doesn't support the debug > > architecture, but then reports to user space that 1 watchpoint and 6 > > breakpoints are supported ... GDB will never use the watchpoint, because > > the maximum watchpoint size is reported as zero, but GDB will attempt to > > use the breakpoints. Setting a breakpoint will appear to succeed, but then > > the breakpoint just never triggers. The kernel should IMO be more > > consistent in how unsupported configurations are handled ... > > Agreed. This is an artifact of how the ptrace info register is populated. > I'll work on a fix tomorrow so that we don't report any resources when > the architecture is unsupported.
Great, thanks! > > - Why is architecture 0x4 not supported? This seems to be the variant of > > the v7 debug architecture with memory-mapped registers. Apparently the > > IGEP only supports this version ... Do you know what the > > Beagle-/Pandaboard and other clones do? What would it take to support this > > architecture variant? Given the widespread use of those boards, it would > > be really nice if we could support hardware debugging on them ... > > The memory-mapped interface is hugely unreliable in real hardware because > you have to calculate the address of the memory-mapped debug registers by > using a base and offset, which are hardcoded in some information registers. > Unfortunately, I've never found a board where these registers have been > programmed correctly so (a) I had nothing to test my code with (b) few people > would be able to use it and (c) there's not really a safe way to go around > poking random areas of memory. Huh, I see. I have no idea whether those information registers contain correct values on IGEP .. > > - Which hardware *is* supported? Can you recommend a board I should be > > using to verify GDB support is working? > > The simple rule is Cortex-A8 is unsupported and Cortex-A9 is supported. > The A5 should work (untested) and the A15 will need a bit of hacking to > get it supported. OK. I guess I can try on our Versatile Express. > > Thanks for your help in getting this working! > > No problem. If you find anybody with working memory-mapped debug and some > spare time, I'd be happy to review patches :) Thanks! I'll try and see if I can figure out where the MM area is on the IGEP ... Mit freundlichen Gruessen / Best Regards Ulrich Weigand -- Dr. Ulrich Weigand | Phone: +49-7031/16-3727 STSM, GNU compiler and toolchain for Linux on System z and Cell/B.E. IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Martin Jetter | Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen | Registergericht: Amtsgericht Stuttgart, HRB 243294 _______________________________________________ linaro-toolchain mailing list linaro-toolchain@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-toolchain
