[PATCH][MIPS] Add linker emulation for N64 ABI with forced 32-bit symbols

Richard Sandiford rdsandiford@googlemail.com
Sun Nov 18 11:41:00 GMT 2012


Matt Thomas <matt@3am-software.com> writes:
> On Nov 15, 2012, at 2:08 PM, Richard Sandiford wrote:
>> 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.
>
> Gee, should we go back and stop making sure VA 0 is unmapped too?  Sure
> it helps find NULL pointer dereferences but isn't that the tools
> lecturing to the user as well?  Having the TEXT_START_ADDR at 5GB
> doesn't hurt anyone and will errant catch 32-bit deferences instead of
> allowing possible silent corruption.  Why is that a bad thing?

It hurts anyone who uses -msym32, or gets given -msym32 archives,
because we'll silently mislink their code.

Richard



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