crosstool-ng/docs/B - Known issues.txt

File.........: B - Known issues.txt
Copyrigth....: (C) 2010 Yann E. MORIN <yann.morin.1998@anciens.enib.fr>
License......: Creative Commons Attribution Share Alike (CC-by-sa), v2.5


Known issues  /
_____________/


This files lists the known issues encountered while developping crosstool-NG,
but that could not be addressed before the release.

The file has one section for each known issue, each section containing four
sub-sections: Symptoms, Explanations, Fix, and Workaround.

Each section is separated from the others with a lines of at least 4 dashes.

The following dummy section explains it all.

    --------------------------------
    Symptoms:
      A one-liner of what you would observe.

    Explanations:
      An as much as possible in-depth explanations of the context, why it
      happens, what has been investigated so far, and possible orientations
      as how to try to solve this (eg. URLs, code snippets...).

    Fix:
      What you have to do to fix it, if at all possible.
      The fact that there is a fix, and yet this is a known issue means that
      time to incorporate the fix in crosstool-NG was missing, or planned for
      a future release.

    Workaround:
      What you can do to fix it *temporarily*, if at all possible.
      A workaround is not a real fix, as it can break other parts of
      crosstool-NG, but at least makes you going in your particular case.

So now, on for the real issues...

--------------------------------
Symptoms:
  gcc is not found, although I *do* have gcc installed.

Explanations:
  This is an issue on at least RHEL systems, where gcc is a symlink to ccache.
  Because crosstool-NG create links to gcc for the build and host environment,
  those symlinks are in fact pointing to ccache, which then doesn't know how
  to run the compiler.

  A possible fix could probably set the environment variable CCACHE_CC to the
  actual compiler used.

Fix:
  None known.

Workaround:
  Uninstall ccache.

--------------------------------
Symptoms:
  The extract and/or path steps fail under Cygwin.

Explanations:
  This is not related to crosstool-NG. Mounts under Cygwin are by default not
  case-sensitive. You have to use so-called "managed" mounts. See:
  http://cygwin.com/faq.html section 4, question 32.

Fix:
  Use "managed" mounts for the directories where you build *and* install your
  toolchains.

Workaround:
  None.

--------------------------------
Symptoms:
  uClibc fails to build under Cygwin.

Explanations:
  With uClibc, it is possible to build a cross-ldd. Unfortunately, it is
  not (currently) possible to build this cross-ldd under Cygwin.

Fix:
  None so far.

Workaround:
  Disable the cross-ldd build.

--------------------------------
Symptoms:
  On 64-bit build systems, the glibc (possibly eglibc too) build fails for
  64-bit targets, because it can not find libgcc.

Explanations:
  This issue has been observed when the companion libraries are built
  statically. For an unknown reason, in this case, the libgcc built by the
  core gcc is not located in the same place it is located when building
  with shared companion libraries.

Fix:
  None so far.

Workaround:
  Build shared companion libraries.

--------------------------------
Symptoms:
  While building the final gcc, I get an error message that ends with:
    libtool.m4: error: problem compiling FC test program

Explanations:
  The gcc build procedure tries to run a Fortran test to see if it has a
  working native fortran compiler installed on the build machine, and it
  can't find one. A native Fortran compiler is needed (seems to be neede)
  to build the Fortran frontend of the cross-compiler.
  Even if you don't want to build the Fortran frontend, gcc tries to see
  if it has one, but fails. This is no problem, as the Fortran frontend
  will not be built. There is nothing to be worry about (unless you do
  want to build the Fortran frontend, of course).

Fix:
  None so far. It's a spurious error, so there will probably never be
  a fix for this issue.

Workaround:
  None needed, it's a spurious error.

--------------------------------
Symptoms:
  gcc barfs because it is "unable to detect the exception model".

Explanations:
  On some architectures, proper stack unwinding (C++) requires that
  setjmp/longjmp (sjlj) be used, while on other architectures do not
  need sjlj. On some architectures, gcc is unable to determine whether
  sjlj are needed or not.

Fix:
  None so far.

Workaround:
  Trying setting use of sjlj to either 'Y' or 'N' (instead of the
  default 'M') in the menuconfig, option CT_CC_GCC_SJLJ_EXCEPTIONS
  labelled "Use sjlj for exceptions".

--------------------------------