Re: [PATCH] powerpc64le build fails with GCC7

[Alexey Neyman <stilor at att dot net>]

On 08/21/2017 02:21 PM, Joseph Myers wrote:
> On Mon, 21 Aug 2017, Alexey Neyman wrote:
>
> > At this point, I am not sure whether it is a GLIBC bug (i.e. it should
> > bootstrap regardless of the TARGET_FLOAT128_TYPE setting in GCC) or a GCC bug
> > (i.e. it should configure TARGET_FLOAT128_TYPE consistently regardless of the
> > headers being present in sysroot). Please advise.
> I think you should investigate further why the difference in
> TARGET_FLOAT128_TYPE.
Michael Meissner has just identified the cause for that difference; it 
is the failing test for "--with-long-double-128". So, the question 
becomes - shouldn't GCC default to 128-bit long doubles on 
powerpc64le-*-linux targets, given this is what GLIBC supports?
> But, it's always a good idea to configure such a
> bootstrap compiler with --with-glibc-version=<whatever>, which should
> avoid any need to find headers in the sysroot.  And on some platforms it's
> necessary to do so if you want to do a bootstrap with only two rather than
> three GCC builds (with the first bootstrap GCC being used to build a glibc
> that's identical to what an alternating series of builds would converge
> on) as otherwise GCC disagrees with glibc's expectations about
> stack-smashing protection mechanisms.
It would not have helped in this case. I'll add this as a further 
enhancement in crosstool-NG, thanks for the tip. Regarding two GCC 
builds, though - does --with-glibc-version=... also obviate the need for 
crt*.o files when building bootstrap GCC (i.e., libgcc)? Currently, 
crt*.o are built using "bootstrap pass-1" compiler and then passed to 
"bootstrap pass-2" so that it can build libgcc.so.

Regards,
Alexey.
>