On 4/9/21 3:03 PM, Michael Matz wrote:
> Hello,
> 
> On Fri, 9 Apr 2021, Mark Wielaard wrote:
> 
>>> We determine native as the result of:
>>> - -p: sizeof (void *)
>>> - -e: __BYTE_ORDER__
>>> when compiling using CC without CFLAGS, such that if we build dwz with -m32 on
>>> x86_64 like so:
>>> ...
>>> $ make CFLAGS="-m32 -O2 -g" LDFLAGS=-m32
>>> ...
>>> and we have:
>>> ...
>>> $ file ./dwz
>>> dwz: ELF 32-bit LSB executable, Intel 80386 <SNIP>
>>> ...
>>> we still have:
>>> ...
>>> $ ./dwz -?
>>>   ...
>>>   -p, --multifile-pointer-size <SIZE|auto|native>
>>>                               Set pointer size of multifile, in number of bytes.
>>>                               Native pointer size is 8.
>>>                               Default value: auto.
>>> ...
>>>
>>> Any comments?
>>
>> Except for this narrow multilib case, doesn't this actually make it 
>> impossible to do a cross-arch build?
> 
> For cross the term "native" doesn't make sense, so it would seem valid to 
> simply not support that setting with a cross (not multilib) dwz.  I.e. if 
> ./native can't be executed assume cross-ness and don't support -p native.
> 

I've tried yet another variant.  Instead of trying to generate an
executable and execute it, we generate an object and test properties
using readelf.

This should no longer have the cross-build problem.

WDYT?

Thanks,
- Tom