Maxim Kuvyrkov <maxim@codesourcery.com> writes:
This patch fixes linking of applications compiled with -mabi=64 -msym32.
The -msym32 GCC options forces MIPS backend to emit 32-bit symbols even
when compiling for 64-bit ABI, which is most useful for building
applications with PLTs to call shared library functions (PLTs are
currently supported only for 32-bit symbols for MIPS). Certain
applications get a significant performance edge from using PLTs, and
such applications should be compiled with "-mabi=64 -mplt -msym32".
Compiling with the above options works just fine until linker tries to
put the .text section above 32-bit address space at
TEXT_START_ADDR="0x120000000". This patch sets TEXT_START_ADDR to
0x10000000 (which is same as for N32 ABI) when compiling with -msym32
GCC option.
I will post the corresponding GCC patch that tells the linker to use new
emulations shortly.
Tested by building complete MIPS64 toolchain (including glibc) with -msym32.
OK to apply?
Huh. I'm very much against the original change to the n64 TEXT_START_ADDR.
See this previous discussion on the topic:
http://sourceware.org/ml/binutils/2008-06/msg00285.html
The justification for changing TEXT_START_ADDR from a 32-bit value to a
larger value was that it would show users if their code was non-portable,
because anything that assumed 32-bit addresses would now fault. But that
seems to me like the tools lecturing to the user. As I said in that thread,
I think users who want to smoke out such portability problems (by making
sure that the lower 4GB aren't mapped) should be the ones who need to do
something special.
I think we should simply revert to a 32-bit TEXT_START_ADDR for all
n64 emulations. This time I'm even in a position to approve it :-)