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Re: GDB single-step fails on alpha (Re: CVS commit: src/share/mk)



On 06.12.2016 13:53, Rin Okuyama wrote:
> 2016/12/06 20:28, Kamil Rytarowski wrote:
>> Not sure if related and relevant, but I noted that OpenBSD defines
>> FIX_SSTEP for alpha.
>>
>> #ifdef _KERNEL
>> # define FIX_SSTEP(p)    process_sstep(p, 0)
>> #endif
>>
>> --- sys/arch/alpha/include/ptrace.h
>>
>> and additional logic in process_sstep()
>>
>>  * process_sstep(proc)
>>  *    Arrange for the process to trap after executing a single
>> instruction.
>>
>> -- sys/arch/alpha/alpha/process_machdep.c
>>
> 
> Hmm, while we do not support PT_STEP on alpha, OpenBSD does. Although,
> GDB uses its own software single stepping both for NetBSD and OpenBSD.
> 

I consider PT_STEP feature as desired with the goal to be independent
from the GNU toolchain and without need to reimplement basic features in
per-platform basis in a custom debugger.

I was trying to find users of FIX_SSTEP() in the NetBSD CVS history (git
log -p|grep) and I couldn't find any users till BSD4.4-lite2 -- it's a
dead macro since then, older code is partially removed and I couldn't
find users back in 1994 year. The alpha port could be the first user!

Thanks on your work on GDB and GCC!


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