Re: [gentoo-musl] What is crtbeginP.o ?

[Anthony G. Basile]

On 6/10/16 7:56 AM, Lei Zhang wrote:
> 2016-06-10 17:15 GMT+08:00 Anthony G. Basile <blueness@g.o>:
>> so i recommend you play with different gcc compiler profiles using
>> gcc-config on the musl based system you built with GRS, and look at the
>> collect2 line to see which end files are deployed with each setting.
>> then i recommend trying to read the gcc spec file for each of the
>> compiler profiles.  then if you know some assembly, look at the code for
>> those end files which you can find in the musl source tree.  that'll
>> give you some idea what's going on there.
>
> Below are my findings after some experimentation:
>
> crt files linked by default, on my glibc based host:
> crt1.o crti.o crtn.o
> crtbegin.o crtend.o
>
> with "-static":
> crt1.o crti.o crtn.o
> crtbeginT.o crtend.o
>
> with "-shared":
> crti.o crtn.o
> crtbeginS.o crtendS.o
>
> This complies with what is written on this page:
> https://dev.gentoo.org/~vapier/crt.txt
>
> Things are a bit different on the musl based system. By default:
> Scrt1.o crti.o crtn.o
> crtbeginS.o crtendS.o
>
> with "-static":
> Scrt1.o crti.o crtn.o
> crtbeginP.o crtendS.o
>
> with "-shared":
> crti.o crtn.o
> crtbeginS.o crtendS.o
>
> This looks like a bit of mess to me...

No, the difference is not glibc vs musl, the difference is non-hardened
vs hardened.

>
> To make it even more confusing, I also found that on the glibc based
> system, crtend.o and crtendS.o are the same; on the musl one,
> crtbegin.o is the same as crtbeginT.o, and crtbeginP.o is the same as
> crtbeginS.o.
>
>
> Lei
>


-- 
Anthony G. Basile, Ph.D.
Gentoo Linux Developer [Hardened]
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