[blfs-support] gcc-4.9.2 installed with --disable-bootstrap

Fernando de Oliveira famobr at yahoo.com.br
Sat Nov 15 07:07:50 PST 2014


On 15-11-2014 11:28, Pierre Labastie wrote:
> Le 15/11/2014 13:43, Fernando a écrit :
>> Hi Pierre,
>>
>>
>> I installed gcc-4.9.2 when the ticket was still open. Today, after some
>> problems with kdepin-4.14.3, comparing my instructions, I saw that
>> switch, in my script:
>>
>>
>>               --disable-bootstrap         \
>>
>> Should it make such a difference that I should reinstall it without that
>> switch?
>>
>>
>> I also use
>>
>>               --enable-languages=c,c++,fortran,go,objc,obj-c++
>>
>> but don't think this is a problem.
>>
> 
> Well, all I can tell you is already in the book ;-):
> "The instructions below are intentionally performing a “bootstrap” process.
> Bootstrapping is needed for robustness and is highly recommended when
> upgrading the compilers version. To disable bootstrap anyways, add
> --disable-bootstrap to the ./configure options below."
> 
> The problem with compilers is that they have to compile themselves
> (bootstrap). If you disable bootstrap, you compile gcc-4.9.2 with gcc-4.9.1
> (or any previous version), and stop there. Bootstrapping allows to first build
> gcc-<new-version> with gcc-<old-version>, then immediately recompile
> gcc-<new-version> with the just built gcc-<new-version>. In a perfect world,
> that should be enough, but the GCC devs have added a third stage, where they
> again recompile gcc-<new-version> with the compiler obtained at stage 2. They
> then compare the third stage compiler with the second stage compiler, and fail
> if there is too much difference. Then, the libraries and other compilers
> (obj-c, fortran,...) are compiled with the C/C++ compilers obtained at stage 3.
> 
> Of course, the first stage could be enough, but I am almost sure upstream
> always test with bootstrapping, so they'll never warrant that stage 1 is enough.
> 
> So, if you are not in a hurry, always "use bootstrap, Luke"...


Thanks.

Reinstalling now, using own version 4.9.2 to build stage 1. Will need to
do it also in the host, but the dev machine is a more serious one, where
I get th updates for the book done.


-- 
[]s,
Fernando


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