This is the mail archive of the
gdb-patches@sources.redhat.com
mailing list for the GDB project.
Re: RFA: MIPS ABI selection
-- Adding the macro MIPS_DEFAULT_ABI to all MIPS targets.
Remember, all the mips/tm-*.h files are going away so this isn't really
going to help. Instead, I think a ``(gdb) set mips abi <tab>.. auto o32
...'' command would be far more useful. Another place the code could
look is the ABI from the previous architecture.
That paragraph is three things:
tm-*.h files are going away: Yes, certainly, and when they do they
will become OSABIs presumably. Those new places don't exist yet. When
they do the default ABI should go in them, and for now I want to put it
in the right place so that it will be picked up and moved over when the
time is right. What's wrong with that?
I don't expect this to happen. As you point out, the
mips_find_abi_section() makes this all somewhat redundant.
"set mips abi": Certainly it's useful, but I'd say it was completely
unrelated to the purpose of my patch.
My understanding of the purpose of the patch was to change the default
ABI to O32. Given that won't always be correct, I think a user command,
(rather than a source code change) is needed to handle the edge conditions.
ABI from the previous architecture: I don't want to do that. I believe
that generating a new architecture should be completely independent of
the previous architecture. If we figured it out the first time we can
figure it out again.
Check how ``set endian big'' works or the ABI mechanism in the CRIS
target. It forces an architecture update with just one field set. The
rest of the architecture information still being taken from the previous
architecture.
-- Some additional MIPS targets
Er, we're trying to get the number of MIPS targets down to zero.
GCC supports configuring for those targets. Binutils supports
configuring those targets. In both cases they get a special default
ABI that doesn't match GDB's. I think that makes the new targets quite
justified.
I think GDB should be able to rely on build and run-time information
provided by BINUTILS (bfd/config.bfd, ...) when making this selection.
I'm also puzzled as to why it was included in the patch.
_HOWEVER_: After I commit the bit to use ".mdebug.abi*" sections, we
will always get the ABI for GCC-produced binaries correct, at least as
far back as I can find GCC releases. After that point I no longer care
what the default case says.
Right!
How about I just commit the part which
says "if no tm- file overrides this, default to O32" and the bit which
removes the default case (which accesses a lot of target macros, ew)?
You mean:
#ifdef MIPS_DEFAULT_ABI
..
#else
if (not set)
set to O32;?
#endif
My problem is that I know it is going to break something. Hence the
need to be able to force the ABI at runtime with a command.
Andrew