Re: Glibc headers in one directory and linux headers in another

[Shaun Jackman <sjackman at gmail dot com>]

Hi, Bryan.

On 2 September 2014 12:04, Bryan Hundven <bryanhundven@gmail.com> wrote:
> Shaun,
>
>>
>> On 28 August 2014 11:30, Shaun Jackman <sjackman@gmail.com> wrote:
>>> I'm attempting to compile a native GCC compiler that uses a newly
>>> downloaded set of Linux headers and a newly compiled glibc. These two
>>> packages are installed in different directories. I'd like to specify
>>> --with-native-system-header-dir twice, once for each set of headers. I
>>> didn't in fact try that, but I'm guessing that it's not supported. I
>>> tried using --with-headers, but it's supported only for cross
>>> compiles. Is there a set of configuration parameters that I can use to
>>> accomplish this? My configure line is:
>>>
>>> ../configure --with-sysroot=/home/sjackman/.linuxbrew
>>> --prefix=/Cellar/xgcc/4.9.1
>>> --with-native-system-header-dir=/opt/glibc/include
>>>
>>> The glibc headers are installed in $sysroot/opt/glibc/include.
>>> The linux headers are installed in $sysroot/opt/linux-headers/include
>>> and also symlinked into $sysroot/include.
>>>
>>> Thanks,
>>> Shaun
>>>
>>> http://sjackman.ca
> On Tue, Sep 2, 2014 at 10:25 AM, Shaun Jackman <sjackman@gmail.com> wrote:
>> The simple work around to this problem is to symlink both the glibc
>> and Linux headers into the single directory specified with
>> --with-native-system-header-dir. It would still be nice to be able to
>> specify multiple header directories. gettext (libintl.h) seems to be a
>> third dependency of building GCC --with-sysroot.
>
> I understand what you are trying to do. My question is to find out
> your intentions; Why do you feel it is necessary to separate headers
> that belong in one $sysroot/$prefix/include directory?
>
> -Bryan

Homebrew is a package manager for Mac OS. I maintain the port of
Homebrew for Linux, named Linuxbrew. The file arrangement in Homebrew
is that each package is installed in $prefix/Cellar/$package/$version
and then {bin,include,lib} of that package are optionally symlinked
into $prefix/{bin,include,lib}. The most recent version of each
package is also symlinked into $prefix/opt/$package. $prefix is the
installation directory of Homebrew, typically ~/.linuxbrew

I'd like to be able to compile GCC --with-sysroot without requiring
that glibc be symlinked into $prefix. Within Linuxbrew, executables
are compiled with their rpath set to $prefix/lib so that they can find
libraries installed by Linuxbrew. Additionally executables compiled
against a Homebrew-compiled-and-installed glibc have the
dynamic-linker set to that of the new GLIBC using
-Wl,--dynamic-linker.

If a particular executable is compiled against the system glibc, and
the new glibc is symlinked into $prefix/lib, it can cause the error
"ELF file OS ABI invalid". I'd like to support compiling executables
either with the system GCC and glibc or the Homebrew-managed GCC and
glibc, which precludes linking libc.so.6 into $prefix/lib due to
setting rpath to $prefix/lib.

For now I'm making progress by symlinking Linux headers, glibc and
libintl.h into $sysroot.

Cheers,
Shaun