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Re: [WIP] glibc: Use /lib/ for ARM's -mfloat-abi=hard ABI.

On Thu, 26 Apr 2012, Carlos O'Donell wrote:

> (b) Detect dynamic linker used by compiler.
> The following new configure test detects the dynamic linker
> used by the compiler given the current set of options.
> We store the result in libc_cv_compiler_dynlinker_default
> for later use in ARM's preconfigure.

This is far too complicated.  GCC isn't detecting what dynamic linker 
glibc has, after all.  We should simply test if the compiler predefines 
__ARM_PCS_VFP, which is easy to do in the ARM preconfigure.

> I caught a couple of problems early and fixed them though,
> like not using AC_MSG_ERROR for the configure failure cases
> because you might be installing headers and not have a compiler
> capable of compiling an application yet. This does imply that
> you *might* not get the right set of headers if such headers
> changed depending on the dynamic linker selected (which
> they shouldn't).
> Comments?

It shouldn't (ideally) be necessary to configure glibc, or GCC, more than 
once when bootstrapping.  See Roland's comments at 
<>.  That means 
we don't want any configure tests that will give the wrong results in a 
bootstrap configuration (where you don't have a preexisting libc so can't 
link things using it) - where there are existing tests we should remove 
them, and we should avoid adding more.

Testing preprocessor defines is safe.  Linking without -nostdlib isn't 
safe in configure tests.  While it looks like GCC will still pass the 
default -dynamic-linker option to ld when using -nostdlib, I don't think 
you should really rely on that either.

Joseph S. Myers

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