[lldb-dev] Port LLDB to ppc64le (ABIv2) on linux

Thu Jul 6 08:37:44 PDT 2017

Hi,

> -----Original Message-----
> From: Howard Hellyer [mailto:HHELLYER at uk.ibm.com]
> Sent: quinta-feira, 6 de julho de 2017 09:59
> To: Gustavo Serra Scalet <gustavo.scalet at eldorado.org.br>
> Cc: lldb-dev at lists.llvm.org
> Subject: Re: [lldb-dev] Port LLDB to ppc64le (ABIv2) on linux
> 
> Hi Gustavo,
> 
> Were you interested in support for live debugging via ptrace or reading
> from core files? (Or both!)

Mainly live debugging, but I have the feeling that implementing post-mortem wouldn't be such a hassle afterwards. (register read/write, stack walk... they would all be done at this point).

> 
> I did have a look at what it would take to add support for Power PC
> little endian core files. I didn't seem too bad as the existing code for
> PPC 64 support just needed to be aware of LE as well. I may be able to
> resurrect the patch if master hasn't diverged too much.
> 
> Live debugging looked a bit more complicated but that's probably because
> most of my experience has been with post-mortem debugging. I think I
> stopped work on the core file support because I didn't have the time to
> learn about the live debugging side and it didn't seem to make sense to
> add core file support without live debug.

Wait. As far as I understood, LLDB already supports ppc64 big endian, right? (particularly the ppc970 model) Plenty of things changed since then but I guess I can use it as a reference (despite endianness, of course).

> 
> Howard Hellyer
> J9 RAS Developer
> IBM Runtime Technologies, IBM Systems
> 
> 
> "lldb-dev" <lldb-dev-bounces at lists.llvm.org> wrote on 05/07/2017
> 20:13:02:
> 
> > From: Gustavo Serra Scalet via lldb-dev <lldb-dev at lists.llvm.org>
> > To: "lldb-dev at lists.llvm.org" <lldb-dev at lists.llvm.org>
> > Date: 05/07/2017 20:13
> > Subject: [lldb-dev] Port LLDB to ppc64le (ABIv2) on linux Sent by:
> > "lldb-dev" <lldb-dev-bounces at lists.llvm.org>
> >
> > Hi,
> >
> > I'm interested in porting LLDB to PowerPC 64 little endian (e.g:
> > POWER8 machines) on Linux platform but before starting such work, I
> > wanted to know if somebody is already doing it or also if there is
> > anything prohibitive in doing so (Probably relevant to this
> > question: clang supports POWER8 already, which is good).
> >
> > The interesting resources I found at the moment are: the special debug
> > registers as described on the ISA [1]; dealing with Ptrace API[2]; and
> > also a presentation pointing out how LLDB was ported to
> > MSP430 architecture[3].
> >
> > Are there any other resources you'd recommend? I tried searching in
> > the mailing list but I didn't find more relevant information.
> >
> > Thanks. Comments are welcome :-)
> >
> > [1]
> > https://openpowerfoundation.org/?resource_lib=power-isa-version-3-0
> > <https://openpowerfoundation.org/?resource_lib=power-isa-version-3-0>
> > (Book III, chapter 8, page 1103)
> > [2] http://www.alexonlinux.com/how-debugger-works
> > <http://www.alexonlinux.com/how-debugger-works>
> > [3] http://llvm.org/devmtg/2016-03/Tutorials/LLDB-tutorial.pdf
> > <http://llvm.org/devmtg/2016-03/Tutorials/LLDB-tutorial.pdf>
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