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Re: MIPS: 64-bit DWARF
On Wed, 14 Jul 2010, David Daney wrote:
> > Here is the patch that I tested for (a non-HEAD version of) binutils.
> > This makes prelink happy, and there are no regressions in the GDB
> > testsuite. (Anything else to test?) I left in the 64-bit stuff for
> > TE_IRIX, as I have no idea about it.
> How was it tested? Have you tested mips64-linux-gnu with -mabi=64?
GCC switched to emitting 32-bit DWARF records on the MIPS/Linux/n64
platform a couple of years ago. GDB as of 6.8 didn't cope at all with
64-bit DWARF records that were generated for n64 binaries before the
switch (for the MIPS platform, that is -- I'd expect it to work for some
others, especially ones that have always been 64-bit like the Alpha) --
the usual symptom was a complete exhaustion of the stack space followed by
a crash (tested natively only). I am strongly convinced GAS should
follow, for consistency if nothing else, and I am rather surprised both
tools were not updated at once.
TE_IRIX refers to the original 64-bit DWARF stuff invented by SGI that
predates DWARF-3 and differs slightly from the latter. This may perhaps
be the reason of the GDB crash -- it may have this SGI variant hardcoded
for the MIPS target or suchlike. Having noticed the GCC switch I have not
investigated it further.
The change needs to be properly tested of course to see if it does not
uncover an odd bug somewhere, but in principle I consider it the right and