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Re: [PATCH] Update relocation values for ARC platform.
I am worried about this. What has happened to the old relocation
values (1, 2, 3) ? What about backwards compatibility ?
FSF mainline was not ABI compliant with respect to these relocation
values. (The relocation values 1, 2 and 3 are actually reserved for the
relocation types R_ARC_8, R_ARC_16, R_ARC_24. ostensibly generated by
the other toolchain for the ARC cores. ) which the GNU tools does not
generate / handle currently.Mainline seems to have the values of 1,2,3
for these relocation types since the first revision.
With respect to backwards compatibility, if anything this should enable
users to link in GNU compiled binaries with the other propreitary
toolchain with a few more patches that are still in my pipeline. A
persistent complaint has been this inability to link object files
generated by the 2 toolsets for the ARC platform .
Ok - that is a reasonable reason to break backwards compatibility,
Would a NEWS item indicating this change be a valid thing to do
indicating that mainline would be broken w.r.t 2.16 branch. ?
Maybe, but see below.
you want to put in some sort of version checks in the linker based on
version info emitted by the assembler ?
Well I think that a nicer solution might be to be put code into
bfd/elf32-arc.c to handle the "old" style relocation values with a
warning that support for them will be removed with the next release of
binutils (ie 2.17). Obviously you would then have to remember to remove
this support after the 2.17 branch is cut, whenever that might be.
If this is too long term for you, eg if you are planning to update the
bfd sources in the near future so that they hand the R_ARC_8, R_ARC_16
and R_ARC24 relocs, then perhaps a heuristic could be developed to
distinguish between an object with the old (non ABI compliant) relocs
and an object file with relocs created by a foreign compiler. The
linker could then issue a suitable error message saying that the old
relocs are no longer supported and that a 2.16 version of the linker is