Re: [PATCH] Add -p native and -e native

[Michael Matz <matz@suse.de>]

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 don't think this should be a compile time option, unless it can 
> derived from the target architecture that the dwz binary is build for.

If it can be derived from the target architecture it can't be called 
native.  If you mean a canadian cross setting (i.e. where the dwz binary 
itself is built on host to be able to run on target and produces binaries 
for target): do we really want to support such build outside the core 
toolchain?


Ciao,
Michael.