[lfs-support] LFS-BOOK-7​.0; Chapter 5.2 Toolchain Technical Notes - clarificat​ions

Emerson Yesupatham yemerson1976 at gmail.com
Wed Sep 5 21:29:24 PDT 2012


Hi Team,

Did you get a chance to look into my below mail? I waited for two days
before sending this gentle reminder.

If you have time please reply to it. Also, if you have any feedback
you can openly give that, I would accept and work on it.

I am little afraid of not getting replies to my queries.

Thanks much,
Emerson

On Tue, Sep 4, 2012 at 12:25 AM, Emerson Yesupatham
<yemerson1976 at gmail.com> wrote:
> Hi Team,
> My below mail got bounced. By mistake I sent it o lfs-support-request.
>
> Hi,
>
> I am going through toolchain technical notes for the second time to
> understand it better.
>
> From the Book:
>  "Slightly adjusting the name of the working platform, by changing the
> "vendor" field target triplet by way of the LFS_TGT variable, ensures
> that the first build of Binutils and GCC produces a compatible
> cross-linker and cross-compiler. Instead of producing binaries for
> another architecture, the cross-linker and cross-compiler will produce
> binaries compatible with the current hardware."
>
> In order to understand the above point, I have cross-compiled the
> binutils as per pass-1 configure instructions. Also I have compiled it
> separately for my config.guess target (basically not cross-compiling)
> and ran the below command and took the difference
>
>>>./ld --verbose | grep SEARCH
>>>SEARCH_DIR("/tools/i686-lfs-linux-gnu/lib");
>
> The search path shows that the cross-linker searches only inside
> /tools/target-triplet/lib folder and not searching in HOST's folders
> like /usr/lib, /usr/local/lib and /lib, thus removes dependency on
> host system.  This part is fine, I could understand.
>
> Coming to the next point.
> "The temporary libraries are cross-compiled. Because a cross-compiler
> by its nature cannot rely on anything from its host system, this
> method removes potential contamination of the target system by
> lessening the chance of headers or libraries from the host being
> incorporated into the new tools."
>
> When we say librarires are cross-compiled, what exactly we mean? In
> libraries also any hard-wired PATHS are present and they are modified
> to /tools/target-triplet/ ?
>  I mean, when we cross-compile the linker (above) it limits its search
> folder within /tools/  , without cross-compilation it would have
> searched in /usr/lib/ etc. Similarly any changes (path names, inculde
> path etc) happens in the library files (say libc.so/.a)?
>
> or by cross-compilation of libraries we mean libraries which are
> present inside /tools/i686-lfs-linux-gnu/lib ONLY are used hence forth
> by cross-linker and cross-compiler?
>
> Thanks for bearing the questions. Looking forward your inputs.
>
> Thanks,
> Emerson



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