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Re: [PATCH v2] Define an error function in the PPC simulator library.

On Thursday, April 13, 2017 10:18:14 AM John Baldwin wrote:
> On Thursday, April 13, 2017 08:25:27 AM Luis Machado wrote:
> > On 04/05/2017 11:33 AM, John Baldwin wrote:
> > > Previously this used the error function from GDB directly when linked
> > > against GDB instead of the error method in the host callbacks
> > > structure.  This was exposed via a link error when GDB was converted
> > > to C++.  The error function invokes the error callback similar to
> > > sim_io_error.
> > >
> > 
> > There is another implementation of error (...) in sim/ppc/main.c and 
> > sim/ppc/misc.c. Should those be kept as is or should we only use the new 
> > function you're providing?
> My understanding is that they should be kept as-is.  This file is only used
> when linking the library against GDB (and actually, rereading the log message,
> I should reword the opening sentence to make this clearer).  sim-calls.o isn't
> included in the actual library.  Each consumer of the library is required
> to export a couple of symbols that libsim.a uses including "error".  The dgen,
> igen, tmp-filter, tmp-ld-decode, tmp-ld-cache, and tmp-ld-insn programs use
> the functions from misc.c.  psim uses the functions from main.c, and
> GDB uses the functions from sim-calls.o.  glibc includes a global function
> called 'error' that libsim.a is linking against when linked into GDB on
> Linux which is why it doesn't fail to link on Linux (but if it ever needs
> to raise an error it probably blows up as error(3) doesn't have the same
> calling convention).
> > Also, i don't see error being implemented in the other sim backends. I 
> > wonder if we should just use whatever is available (sim_io_error?) 
> > instead of supplying our own ppc-specific version?
> Other sims don't use an "error" function (ppc seems to be special in this
> case).  I think Pedro took a stab at replacing "error" (there's a thread
> with the subject "gdb-7.12-powerpc-rtems4.12-gdb does not build on FreeBSD"
> on gdb@) but thought this approach was simpler (and could also be merged
> to 7.12 though that may be OBE by now).


John Baldwin

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